BritishV8 Forum

OK I'm waffling on cam choice. I've been looking at the Crower 50233 but I fear the taller lift. Here's specs:
http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=50233&x=0&y=0

Then there is the square Isky 621282 it has pretty good duration but not so sure if the lift is enough:
http://cgi.ebay.com/ebaymotors/_Car-Truck-Parts-Accessories__Buick-Olds-215-300-340-Isky-camshaft-kit-cam-RACE-282H_W0QQitemZ200195955701QQadnZCarQ20Q26Q20TruckQ20PartsQ20Q26Q20AccessoriesQQadiZ2865QQcmdZViewItem?_trksid=p3756.m20.l1116


I don't want to make a poor decision. My project a 5.0L Rover/Buick stroker with 11.5:1 compression. I've built a 750 Qjet for it on a single plane manifold. I could also adapt the Performer and I planned on trying both on the engine dyno. I figured I'll put the redline at 6800. The valves are 1.72 int. and 1.496 ex with 1.6 ratio roller rockers.

Any input is much appreciated.

OR this one:

http://store.summitracing.com/partdetail.asp?part=CRN%2D890631&autoview=sku

Nick, I don't see a whole lot of difference in those cams except that the Crane has a lower powerband. But based on the duration and lift that could be wholely a function of valve spring pressure since there're no spring specs for the Crane or Isky. They're all three real similar, and you're going to have a wild ride with any of the three.  The lobe profile could be considerably different on all three cams though and without looking at that you really have no way to compare how they are going to act. Obviously a flatter profile with steeper ramps is going to make more power but also need stiffer springs. Plus you've got what, 4 degrees of variation there in lobe separation? I think you need more specifics from each of the grinders.

From my own experience with these engines, you *can* live with the hot cam but you may not want to if you plan to drive the car a lot. In which case something midway between these and stock specs is going to work out nicely and you can upgrade the springs to get into the higher RPM range. But I'd also like to offer one caution. Don't start out with the hot stick and then try to dial back. If you do that, next thing you know you'll be putting a blower on it to get the power back. If that's not a problem I'd lean towards the Isky with the Crower a close second choice, but that's mostly personal preference.

Jim

Nic. Dont let numbers scare you.
If you are going with the E-85 Id be tempted to try the Crower cam.. It has basically the same duration and a little higher lift and its ground on a 112 LSA ......that should idle smoother than the ISKY cam with the 109 LSA

I guess my biggest concern is the lift. I have a Crower 50232 from way back. It's kinda set up for the 215. I figured since I added displacement I'd increase the cam profile.

SO I just went back and checked the lobe lift between the two Crower cams and it's the same at 0.31". My fear about spring bind is gone since I had the heads set up initially for the 50232 anyway. The suggested spring load is the same too. It looks like the only difference is the duration. Cool. I think I'm going to go with my initial thought and go with the Crower 50233.

Thanks for th input, guys. I'm feeling more at ease. Good advice, Jim. LOL! I have a feeling that's what happened to you.

So now you have a cam and an intake with no home.. Give me a call before you sell them .

Cool. I'll keep you in the loop.

Good advice, Jim. LOL! I have a feeling
> that's what happened to you.

Sort of. I put in the hottest cam CC made for the SBB back in about '85 with stiff springs and Rhodes lifters and it was a screamer to be sure. But not knowing the Rhodes are noisy I made the mistake of swapping out a lifter and wiped out that cam lobe so I thought I'd try a different cam. I chose the Kenne Bell one that looked just a half step milder and it just never was the same. Took me a couple of engines before I was back above that power level, one of which was a turbo setup. But it could be just me, I'm well above that point now and it still isn't enough. Not sure why that is exactly, but I do miss the high redline. Starting to think a set of forged pistons might be a good investment and that's a dangerous line to cross. Things just get more and more expensive from there on out.

Jim

> OK I'm waffling on cam choice.

You might want to take a look at the post I made here:

 http://thewedgeshop.21.forumer.com/viewtopic.php?t=71

on cam theory and Rover V8's.  

I ran Vizard's cam selection rules on your engine (3.74" bore, 3.4"
stroke, 11.5:1 compression ratio, 1.72" intake valve) for 75 degrees
overlap (consistent with a hot street motor) and got:

 290 degrees seat duration
 108 LSA
 0.5"+ lift

The lobe separation angle is the important figure here.  If you
want to lower the RPM band, reduce the duration but keep the LSA.
Note that as you go up in displacement, you need to narrow the lobe
center for best performance.  The Crower hydraulic catalog grinds
are all ground on 112 lobe centers, though their solid flat tappets
are 108:

Crower solid flat tappet cams
P/N   Grind  adv dur  0.050   lift       LSA  RPM Range    
50303 282FDP 282/287  238/242 .482/.488  108  2000 to 5500/ redline 7000 300
50304 292FDP 292/298  246/250 .502/.514  108  2500 to 6000/ redline 7500 340
50305 304FDP 304/310  256/262 .536/.549  108  2500 to 6000/ redline 7500 340
lash 0.022" intake/0.024" exhaust

The Isky 282 is on a 109 LSA but Ted at TSI Imported Automotive has
a custom Isky 264 on a 108 but it has a fair bit less overlap (i.e.
a lower RPM band):

Isky  Grind  adv dur  0.050   lift       LSA  
      264    264/264  ---/--- .480/.480  108
      270    270/270  216/216 .470/.470  109  
      282    282/282  224/224 .467/.467  109  

Woody Cooper at the Wedge Shop (thewedgeshop.com) has probably the most
experience in the States with engines like you are building and has a range
of custom Erson grinds he runs in Rover/Buick strokers.  I'd give him a call
and tell him what you're doing and see what he has to offer.  You are giving
up a lot with the 112 lobe center of the Crower 50233.

> Harland Sharp roller rockers 1.6 ratio. COOL!

Did you verify this?  I have it in the back of my mind they were more like
1.55:1 but I'm not sure why.

> I put in the hottest cam CC made for the SBB back in about '85 with
> stiff springs and Rhodes lifters and it was a screamer to be sure.
> But not knowing the Rhodes are noisy I made the mistake of swapping
> out a lifter and wiped out that cam lobe so I thought I'd try a
> different cam.

The Rhoads lifters need the pre-load to be set but the Rover/Buicks have
non-adjustable valvetrain.  The previous owner installed them in my
TR8, along with a Crane H-216 cam.  He used adjustable pushrods to set
pre-load but they were still noisy.  I decided to replace them with a
set of standard lifters but the Rhoads lifters were flat on the bottom,
indicating wear.  The cam looks good but I decided not to chance it and
ordered a new cam.  The old cam was:

 Crane H-216/285-2S-12
 266/278 degrees duration (advertised)
 0.456/0.480" lift
 112 LSA
 48 degrees overlap

The new cam is:

 Erson RV10/RV15 (Wedge Shop custom grind)
 280/288 degrees advertised duration (208/214 @ 0.050")
 0.448"/0.460" lift
 111 lobe separation angle
 4 degrees advanced when installed straight up
 62 degrees overlap

My application is a Triumph TR8 with a stock long block, tri-y headers,
dual exhaust, Edelbrock Performer Rover intake and 500 CFM AFB.  With
only 8.15:1 compression ratio, you can't get too crazy with the cam specs.
The above Erson grind from Woody at the Wedge Shop is one he's found works
well in applications like mine.

Dan Jones

OK on the cam situation: I called Woody from the Wedge shop. I had a really great conversation with him. He's a like minded guy. What's cool is that he's built a few of these engines and has had a bunch of time to experiment with different profiles.

I ended up going with a cam that sounds crazy radical: Solid lifter, 314 adv dur, and .544 lift. The LCA is 108º. It all sounds crazy but he actually drives a version of this cam with an LCA of 106º and recently got almost 20mpg on a recent power tour. It was a big surprise to him.

There are a lot of factors that make the cam right for the engine: Valve angle and position, Valve to bore ratio, Rod ratio, I'm using 1.6 roller rockers, CR 11:1.

I'll report how it works out when I can finally run the engine. Sounds pretty wicked. Looks like I'm going down the road Jim warned me of. Well I guess we all have to make our own way of it, right? LOL. Thanks for all the advice guys.

> OK on the cam situation: I called Woody from the Wedge shop.
> I had a really great conversation with him. He's a like minded
> guy. What's cool is that he's built a few of these engines and
> has had a bunch of time to experiment with different profiles.

I thought you might benefit from his experience.

> I ended up going with a cam that sounds crazy radical: Solid
> lifter, 314 adv dur, and .544 lift. The LCA is 108º. It all
> sounds crazy but he actually drives a version of this cam with
> an LCA of 106º and recently got almost 20mpg on a recent power
> tour. It was a big surprise to him.

I show three Erson lobes:

 HIFLOW IM    242   286   .340  0.015 0.544
 HIFLOW IIM   246   296   .340  0.015 0.544
 HIFLOW IIIM  254   306   .340  0.015 0.544

I wonder if they have an updated lobe?  When you get the cam,
please post the cam card and valve spring info.  Did Woody
recommend helicoiling the cylinder heads where the rocker stands
bolt down?  What sort of oil do you plan to use?

Dan Jones

It's being worked out now and I will post every detail when I get it. It will be about a week or so. I already sent off a payment. BTW his spring sets are about $65. CHEAP!! The whole thing was a lot less expensive than I expected. I'll post an itemized list of the = cost details as they come through too. It sounded like around $250-$280 for a custom ground profile!

I will have to get the proper lifters from TA and that's not cheap. He thought it was around $230ish for a set. I actually did already have the heads helicoiled. It was SOP for my shop I guess. I didn't know it added strength to the perches. Interesting. I also have the D&D rocker shaft end supports. That should help me get through the effective RPM range he runs. His said his experience with this cam was it produced power to about mid 6k range. He figured 6800 was a good redline for the setup.

I'm pretty excited. I can't thank you enough for pointing me in his direction. It was really great talking to another motorhead that builds my engine too. It just doesn't happen very often. Good times. I can't wait for the engine dyno!

Some pretty interesting info, though I won't pretend to follow all the details. Should be a real strong motor, and that 6800 redline is bound to spoil ya.

If you guys are about through with Nick's combo I've got another one for you to consider, which will probably need a custom cam, but I'm not deep enough into it to figure out what the best setup would be. If you'd like to take a shot at it, here's the specs:

340 short block .030 over with stock high compression cast pistons
'64 300 heads with stock valves, about 10:1 compression
Eaton M-112 blower, intercooler, and port injection, boost probably around 8 psi, maybe a little more.
Equal length headers with 1-1/2" x 32" primaries and 2-3/8" collectors dumping into glass packs
6 grand redline based on the pistons. The valve springs can handle about anything I want to throw at them, about a 90 lb seat pressure and real good open pressure, they were good for an easy 7 grand in a 215.
This is supposed to be an economy motor for good gas mileage, and I'd like to see how far I can take that and still get something like 300+ hp out of it.

Obviously the blower throws a curve in things, since the intake side will easily flow enough under boost to produce the desired output even with a stock cam profile, but the exhaust side could use a little help as the exhaust valves are arguably a little undersized to begin with.

What do you guys think, want to kick this combo around a bit?

Jim

FYI
I was talking to the Crane Rep at the NHRA Lucas oil nationals and  he said they can no longer get cores for the Buick 215, 300, 340 but could do roller cams..

There are only really a few suppliers of cores.. does this mean that other manufacturers will soon be using up what they have on hand?  Or is the Crane rep full of hooey?

I wonder if they are just loosing the "215,300,340" listing. Maybe the just say Rover now??

> Obviously the blower throws a curve in things, since the intake side will
> easily flow enough under boost to produce the desired output even with a
> stock cam profile, but the exhaust side could use a little help as the
> exhaust valves are arguably a little undersized to begin with.

Yes.  The old B&M blower catalog had a note when running their blower
on stock Ford Windsor heads that the blower could overheat due to the
restrictive exhaust and the Windsor has larger valves than the Buick 300.

> What do you guys think, want to kick this combo around a bit?

I don't have much experience with blower cams but typically they
run less overlap via wider lobe centers so you don't blow the
compression out the exhaust before it closes.  A typical Ford 5.0L
blower cam has 112 lobe centers with longer exhaust duration.
Some run the stock 5.0L cam which has 116 lobe centers (single
pattern with 204 degrees duration and 0.444" lift w/1.6 rockers)
and Crower's 351C blower cam is 114.  Anderson Ford Motorport has
a series of blower cams for the 5.0L Ford and the mildest specs out
at 218/226 degrees @ 0.050", 112 LSA, 0.542"/0.542" (this is a
hydraulic roller cam).  Closest off-the-shelf Buick cam would be
on of the Crowers, either the 50232 or 50233:

 50232 276HDP 276/281  214/218 .488/.490  112  
 50233 280HDP 280/286  220/226 .488/.501  112  

If you're interested, I've got both of those cams (new) here that
I'd sell.  Looking at the Erson lobes, the closest match to the
AFM blower cam would be a Hiflow AH intake lobe with a Highflow IH
exhaust lobe (220/228, 0.504"/0.504") on 112 centers.  If fuel
economy is a concern, maybe 114 lobe centers or even an RV15H intake
lobe:

 RV10H       208  280  0.280  0.448
 RV15H       214  288  0.288  0.461
 TQ20H       214  292  0.299  0.478
 TQ30H       226  310  0.310  0.496

 Hiflow AH   220  284  0.315  0.504
 Hiflow IH   228  296  0.315  0.504
 Hiflow IIH  235  306  0.315  0.504
 Hiflow IIIH 240  316  0.315  0.504

You might want to run this by Woody at the Wedge Shop (he works with
Steve Tanzi at Erson on the custom grinds).

> I was talking to the Crane Rep at the NHRA Lucas oil nationals and
> he said they can no longer get cores for the Buick 215, 300, 340 but
> could do roller cams..

Were they talking about hydraulic or solid roller cams?

> There are only really a few suppliers of cores.. does this mean that
> other manufacturers will soon be using up what they have on hand?

That would be bad.

> I wonder if they are just loosing the "215,300,340" listing. Maybe
> the just say Rover now??

Crane no longer lists the cams in their catalog.

Dan Jones

Dan.. he didnt specify what type of roller cams... Im assuming they would be custom billet but im not sure if there is a roller cam core or not.

I've not officially got a spare Crower 50232 if anybody is interested.

Hello, here some selection of cams aviaible for Rover V8 in Europe:

Make   Number   Timing   Period   Valve lift   Lifters   Class   Comments
Oselli   RV8255   22/62/62/22   264°   .421"   Hyd .   Mild Road   Extra low and mid end power. Good for towing/load carrying.
Oselli   RV8271   28/64/64/28   272°   .439"   Hyd .   Road   Improves mid and top end power. Good flexibility.
Oselli   RV8214   31/73/80/34   284/294°   .469 "/.494"   Hyd.   Road   Good all round improvement.
Oselli   RV8286   44/72/72/44   296°   .439"   Hyd .   Road   Excellent road cam. Ideal for fuel injected engines.
Oselli   RV8480   36/76/76/36   292°   .480"   Hyd .   Fast Road   Extra mid and top end power. Ultimate for auto-transmission.
Oselli   RV8502   37/77/77/37   294°   .495 "   Hyd .   Road/Rally   Slightly lumpy tickover. Good power 2000 rpm upwards.
Oselli   RV8224   36/78/85/39   294/304°   .494"/.520"   Hyd.   Road/Rally   Extended top end power with up to 7000rpm
Oselli   RV84   35/71/71/35   286°   .516"   Hyd.   Rally   Good all round competition cam. Power band 2500-7000 rpm
Oselli   RV8481   42/82/82/42   304°   .496 "   Hyd.   Rally   Poor low end tractability. Power band 3000-7000 rpm
Oselli   RV8234   38/80/87/41   298/308°   .520"/.542"   Hyd.   Rally   Poor idle and low end but excellent power over 3500 rpm
Oselli   RV8500   46/82/82/46   308°   .542"   Hyd .   Race   Ultimate hyd. camshaft. Power band4000-7000 rpm
Oselli   RV8900   42/78/78/42   300°   .500"   Solid   Rally   Poor tickover. Excellent mid and top range power.
Oselli   RV8100   47/83/83/47   310°   .530"   Solid   Race   Maximum power for full race spec, engine.High rpm.
Kent   H180   28/64/64/28   272°   .439"   Hyd.   Mild Road   Good for automaticsPower band 1000-4500 rpm
Kent   H200   20/64/69/25   264°   .435 "/.460"   Hyd   Mild Road   For pre-SD1. Also good for automatics.
Kent   H214   31/73/80/34   284°   .469 "/.494"   Hyd.   Fast Road   Very flexible. Power from 1500-5000 rpm.Good road camshaft.
Kent   H224   36/78/85/39   294°   .494"/.520"   Hyd.   Road Rally   Slight loss of flexibility. Power comes in 2000-5500 rpm.
Kent   H234   38/80/87/41   298°   .520" /.542"   Hyd.   Rally   Poor low end, but improves mid and top end power.
Kent   GPA   44/76/76/44   300°   .390"   Hyd.   Rally   Same valve lift as standard engine (.390")
Kent   M238   42/78/78/42   300°   .512"   Solid   Rally   Higher rpm use. Power band from 2750-7000rpm.
Kent   M248   48/82/84/46   310°   .533"   Solid   Rally/Race   High rpm camshaft. Power band from 3500-8250rpm
Kent   M256   42/70/83/39   310°   .546"/.564"   Solid   Race   Ultimate race cam. Full race engine only. Power 4000-8250 rpm
Piper    HR270   22/62/64/28   264°/272°   .421"/.439"   Hyd.   Road   Flexible with good mid and top end improvement.
Piper    HR270/2   28/64/64/28   272°   .440"   Hyd .   Fast Road   Mk1 1 of above cam.
Piper    HR285   44/72/72/44   296°   .439"   Hyd.   Fast Road   Ultimate road cam. Tractable but slightly lumpy tickover.
Piper    HR300   36/68/68/36   284°   .440"   Solid   Competition   Accent on mid-range power. Power band 3000-7000 rpm.
Piper    HR320   52/84/84/52   316°   .471"   Solid   Race   Mid and top end power. Excellent circuit race cam.
Crane   H-194   10/54/59/15   244/254°   .400 "/.430"   Hyd.   Road   Economy cam only. Not to be used with comp. ratio over 8.75:1
Crane   H-204   15/59/65/21   254/266°   .430"/.456"   Hyd.   Mild Road   Improvement over standard cam. Can be straight swap.
Crane   H-216   21/65/71/27   266/278°   .456 "/.480"   Hyd.   Road   Excellent all rounder. Good power increase across rev. range.
Crane   H-224   36/78/85/39   294/304°   .494"/.520"   Hyd.   Fast Road   Slightly lumpy idle. Good for lighter vehicles eg. sports cars.
Crane   H-234   38/80/877/41   298/308°   .520"/.542"   Hyd.   Road/Comp.   Ultimate hyd. cam but compromise in road car.
Crane   F-228   38/72/74/36   290°   .491 "   Solid   Road   Particularly suitable for turbo or supercharging.
Crane   F-238   42/78/78/42   300°   .512"   Solid   Road/Comp.   Wide power band. Does not need high rpm.
Crane   F-248   48/82/84/46   310°   .533"   Solid   Rally   Wide power band. Works well with Holley 4-barrel carb.
Crane   F-256   42/70/83/39   292/302°   .546"/.564 "   Solid   Competition   Good mid and top end power.
Crane   F-266   47/75/88/44   302/312°   .564"/.584"   Solid   Competition   Out and out power. Engine must be capable of high rpm.
Crane   F-276   52/80/93/49   312/322°   ,584"/.602"   Solid   Competition   Radical race engines only. The ultimate.
JE Motors   JE101   20/65/25/20   265/225°   .430"   Hyd.   Road   
JE Motors   JE102   43/79/79/43   302°   .500"   Hyd.   Fast Road   Good power from 3000-6500 rpm. Peak torque 5000 rpm
Holbay   111R   39/73/73/39   292°   .429"   Hyd.   Fast Road   The Tornado
Holbay   125LHC   40/84/89/45   304/314°   .520"/.541"   Hyd.   Competition   Designed for maximum performance within rpm limits of hyd. lifters.
Holbay   K3A   58/88/74/50   326/304°   .432"   Solid   Competition   High torque design.
Holbay   751R   63/95/95/63   338°   .451 "   Solid   Competition   Maximum bhp at higher rpm.
Holbay   Standard   30/75/68/37   285°   .390"/.385"   Hyd.   Production   3. 5-litre (SD1)
Rover   Standard   32/73/70/35   285°   .390"   Hyd.   Production   3.9-litre (designation ETC 8686)
Rover   Standard   28/77/66/39   285°   .390"   Hyd.   Production   4.0-litre (designation ERR 3720)
Rover   Standard   14/70/64/20   264°   .416"   Hyd.   Production   4.6-litre (designation ERR 5250)

On Jim's cam: I was thinking bigger lift was better for forced induction. It sounds like thats what the Ford likes. Does rod ratio change duration? I would think that would only effect lift.

I bet longer rod ratios probably help too because of faster piston speed at BDC. That's got nothing to do with cams though.

WHOA, Dimitri. Thanks man. I guess I sat on my post for an hour. I didn't see it before now. (edit)

Actually this brings up a good point. How do you read the "Timing" numbers?

Looks like I may be trying to hit a moving target here. May have a deal on some Carrillo rods and Venolia pistons and obviously if that happens redline is going to go up, probably to the 6500-7000 range. But I'd like to keep the valve lift under .500 if it's feasible, and as mentioned shoot for max economy at the same time. Those are some pretty conflicting demands right there and I don't think it'd be possible without the blower. But I do love an engine that will wind up so why not go for it? I'm thinking wide lobe centers, minimum overlap, and near stock lift and duration on the intake, say around .400 on the lift, and then max out the lift and duration on the exhaust. I'll have to see what clearance my exhaust valves have at the seals and I'd prefer not to have to notch the pistons.

I have little doubt the end result will be a custom grind but I'm not concerned about that, I just want to get in the ballpark with the specs before I talk to the cam grinders. Wonder if Racer Brown is still around?

Jim

Hello Nick, sorry was away.

Cam figures : BTDC/ABDC/BBDC/ATDC
Last figure give you the duration. Two figures when In/Ex duration is different.

LCA (lobe centre angle) : (duration/2) - valve opening point for the inlet or closing point for the exhaust
LSA (lobe separation angle) : (inlet LCA + exhaust LCA)/2

If I can give you an advice contact Rob at V8Developments in UK. This is the man for stroked Rover V8. He created an 5.5 with custom 3.7'' stroker crank and 3.8'' bore http://www.v8developments.co.uk/

WOW that's a lot more specific information. I like that method WAY better. Why don't we do it? I mean, you can get a card from Crower website, which is great, but most don't have that information readily available. I couldn't find anything specific like that about Isky. Is that because they want to keep it a secret?

I love it when the only information is: Street-strip or Race cam. WOW that's helpful. OK... I'm starting to sound like a crotchity beeotch.

My point is: Thanks Dimitri.

OK I got my cam specs from Woody at the Wedge Shop. It makes a lot more sense now:

LCA: 108º
Overlap: 74º
Timing: 35/71/75/39

Clearance Hot: 0.023

Lift: .544/.544

Adv Duration: 286/294


Specs @ 0.050:

Overlap: 38
Timing: 17/53/21/57

Duration: 250/253

It's a solid lifter cam. Custom ground to get the LCA. What Woody was saying to me over the phone is it's a 340 cam not 314 like I thought I heard. At the time I thought he was either talking about the lobe lift or the adv. duration. It's actually the lobe lift. It's got some pretty wicked lift. Hopefully I will clearance OK. 286/294 makes a lot more sense to me. We'll see how it all assembles.

Thanks again for the help guys.

Hello Nick,
I found back an very good article from Rob about cams in Rover V8 :

I will come to cams and what I think are good and bad in a bit, firstly what are you trying to achieve is to get the engine to fill its total cylinder capacity throughout its rev range, easy said impossible to do unfortunately,
The first place to start is the cylinder heads, a real good flowing pair of cylinder heads means you don't need such a viscous cam to make decent horsepower!, unfortunately this is what lets the rover engine down big time, even in the 500 TVR heads the valves are just no where near big enough to flow the air that is required, so we are left with trying to make some decent bhp and drivability with a cam.
LIFT,
basically as much lift as you can get the better your engine will perform through the whole rev range regardless of cc's, the rover head flows it most cfm when the valve is something like 700 thou from is seat, the reality here is no rover cam lifts that far because it just cant, 600 is about its max, lift is related to duration, you cant have lots of lift with little duration as the valve will be being opened so quick that the cam follower will just dig into the side of the cam profile and break, so with a 600 though lift you are going to need 320 deg of duration, what you now have is a full circuit race cam that will only make power from 5000 rpm upwards!
DURATION
Duration is the time the valve is lifted of its seat, to little you will have no power too much the car will drive like a pig, However duration, LCA "lobe center angle, and overlap are all related, its not so much the duration that kills drivability its the overlap, just 10 deg can make or break the engine!, so duration make bhp lift makes both, as I said in the other post I am only going into road engines!.
The LCA is the angle between full lift on the inlet and full lift on the exhaust lobe, by making this wider you can tame the cam for the same given duration, however what will happen is the cam with the wider LCA will idle better drive smoother make more bhp and have a wider torque curve, the cam with the smaller LCA will only have a benefit in the mid range, around peak torque. so in my honest opinion for a road cam i like to go for around 285-290 deg of duration with a wide LCA around 114, this to make a good road sports cam, you can drive it down the shops with no hunting and use it on a track day as well, the same cam on a 108 LCA will make it more peaky in the mid range, but you will have to keep changing gears in slow traffic and it will drop of the cam quicker too, peak power will be around the same but where the 114 will still be making good power at say 6500 rpm the 108 will be dead and buried and need a gear change, a race car is totally different i would spec a a cam to work in the rev range I wanted and make the most of that rev range.
mc1 good idle, excellent drive ability, reasonable bhp.
mc2 poor ish idle, poor ish drivability good mid range, good bhp.
h404 very poor idle, crap drivability, good mid range, excellent bhp
stealth very good idle, very good drive ability, ok ish mid range, good bhp.
Piper 270 ok idle good mid range crap bhp
Piper 285 crap idle, poor drive ability, very good mid range, ok bhp, falls off the cam very quickly
Piper 300 crap idle crap drive ok mid range good bhp
Kent 200 very good idle good drive poor every where else
218 good idle good drive good mid range poor bhp
214 ok idle ok drive ok mid range ok bhp
224 poor idle, poor drive, good mid range, good bhp
234 crap idle crap drive, good mid range, excellent bhp,
These are all based on the fact that you will be running standard management systems and a plenum, there are of course many more cams out there but these are the general ones you will buy.
So to sum things up a bit, if you want a good low down nice driving torque cam go for a cam with a max of around 270 deg duration and a LCA of around 112 deg.
if you aren't bothered with idle qualities and want a good mid range cam go for one with a low LCA and around 280 deg of duration.
if you want a track day cam or fast road cam go for around 300 deg and around 110 lca
if you want a good all rounder go for around 285 deg and wide 114 LCA, both Kent and Piper will make cams to what you want within reason so give them a call, the Piper 285 for instance, loses nearly 25 bhp over the 404 at the top end, this on a controlled dyno not a rolling road, but it gains around 10 ftlb at around 200-3000 rpm, but if you asked Piper to grind it on an LCA of say 110 you would only be losing around 10 bhp at peak, 300 but gaining around 20 ftlb at 2000-3000.
Also please note cams cannot be judged against other cams on rolling roads, especially different rolling roads, there are too many variants, all the way from the air filter to the oil in your gearbox and diff!!!!!
Throttle bodies against plenums and cams!!
What I briefly said earlier with overlap cams, this will murder an engine running a plenum, where as on throttle bodies it tends to smooth thigs out a bit, take a single plenum all 8 cylinders draw from this one opening, not a problem there in fact it is good as each cylinder can draw as much air as it wants with no restrictions as far as air flow is concerned. The BIG DOWNSIDE TO A PLENUM, on the overlap period part of the cam, this is where both exhaust and inlet valve are open at the same time, i.e. at the end of the exhaust stroke where the piston is forcing the burnt gas out the exhaust port the inlet valve opens before the exhaust is shut, instead of the unwanted rubbish going out the exhaust it is sent back up past the inlet valve and into the plenum, this is more aggravated by the fact that the next cylinder is sucking hard and will suck the waste out of the disposing cylinder into the good one, the problem here becomes that it is not fresh and lacks oxygen, so instead of the new cylinder getting a good charge of fresh air and fuel, it has 20 or 30% of nothing that cant be ignited, hence poor combustion poor idle and low power, This is only at low ish rpm, at high rpm you have the advantage that the exhaust manifolds are "should" be scavenging the fresh inlet charge into the cylinder, if you have the money to go to throttle bodies then this is where the biggest gain is going to come in the low to mid range, on the overlap period each cylinder can only contaminate its own cylinder, and part of this will be lost to the atmosphere anyway, so generally lets say at below 3000 rpm a plenum is giving a cylinder 70% of fresh charge to be ignited a set of throttle bodies will be giving 90% at the equivalent rpm all this = more ftlb of torque, just be careful you don't go too small on the throttle bodies or this will hurt the top end breathing, you have gone from a 72 mm plenum and as I said each cylinder will see 72 mm down to what ever size your throttle body is.

Hope it helps you.

> basically as much lift as you can get the better your engine will perform
> through the whole rev range regardless of cc's,

That assumes the high lift lobe shape lends itself to the maximum RPM
you are after.  Most cam grinders typically have two primary families
of lobe shapes (along with a host of others for specialized applications
like racing classes with lift limitations or stock lifter requirements,
etc.).  The first family of lobe shapes are optimized for shorter rocker
ratios or lower RPM when used with longer rocker ratios.  These are
sometimes referred to as high torque grinds.  The second family of lobes
are ones designed for higher RPM and/or longer rocker arm ratios (1.7:1
to 1.8+:1).

> the Rover head flows it most cfm when the valve is something like 700
> thou from is seat

Not on any Rover or Buick 215/300 head I've ever had on the flow bench.
Stock Rover heads plateau by 0.5" lift and even my ported Buick 300
heads with 1.775" intake valve peaked at 0.550" lift.  This is largely
a consequence of the valve diameter.  That said, a cam with higher lift
means more time spent near (or above) the heads peak flow.

> lift is related to duration, you cant have lots of lift with little duration
> as the valve will be being opened so quick that the cam follower will just
> dig into the side of the cam profile and break, so with a 600 though lift
> you are going to need 320 deg of duration, what you now have is a full
> circuit race cam that will only make power from 5000 rpm upwards!

That's lobe lift.  Valve lift is lobe lift times the rocker arm ratio
so you can get greater lift from the same cam by increasing rocker arm
ratio.  Unfortunately, the stock Rover ratio is 1.6:1 and no larger
ratios are easily (read affordable) available.  On another engine I'm
currently working on, the stock ratio is 1.73:1 with 1.8:1 optional.
For that engine (351C Ford stroker), I had to go to shorter rocker
arm ratios (1.7:1 intake and 1.6:1 exhaust) to keep lift under 0.620"
(the limit the BBC beehive valve springs can tolerate), even with a
street cam (hydraulic roller).

For flat tappet cams, the maximum lobe lift slope is determined by the
diameter of the lifter.  Unfortunately, the Rover diameter is 0.842"
(same as other GM V8's such as the small block and big block Chevys,
Pontiac and Buick V8's).  Small and big block Ford V8's use a larger
0.875" diameter and Chrysler and AMC V8's use an even larger diameter
of 0.904".  One way around the lifter diameter limitation is to use
mushroom tappets which have a face that is larger than the lifter
diameter.  The downside is the lifters have to go in from the bottom
side of the block, before the crankshaft goes in.

> Duration is the time the valve is lifted of its seat, to little you will have
> no power too much the car will drive like a pig, However duration, LCA "lobe
> center angle, and overlap are all related, its not so much the duration that
> kills drivability its the overlap, just 10 deg can make or break the engine!

Overlap is much more important than duration.  Overlap is the period when
both intake and exhaust valve are open.

> The LCA is the angle between full lift on the inlet and full lift on the
> exhaust lobe, by making this wider you can tame the cam for the same given
> duration

Because you've decreased the overlap.  Overlap is the combination of duration
and LCA.  The best approach is to pick the total overlap to set your desired
RPM range, choose the optimal LCA for your particular engine and then duration
will fall out of the equation.

> however what will happen is the cam with the wider LCA will idle
> better drive smoother make more bhp and have a wider torque curve,

A wider LCA does not necessarily make better peak or average HP.

> the cam with the smaller LCA will only have a benefit in the mid range,
> around peak torque.

In many engines, particularly Rover storker engines, tighter lobe centers
will make better power across the rev range.

> so in my honest opinion for a road cam I like to go for around 285-290 deg
> of duration with a wide LCA around 114, this to make a good road sports cam,
> you can drive it down the shops with no hunting and use it on a track day
> as well,
>
> the same cam on a 108 LCA will make it more peaky in the mid range, but
> you will have to keep changing gears in slow traffic and it will drop off
> the cam quicker too, peak power will be around the same but where the 114
> will still be making good power at say 6500 rpm the 108 will be dead and
> buried and need a gear change,

That's not a apples-to-apples comparison.  For a valid comparison, you
need to have equivalent overlap.  In the above example, the 108 LCA cam
has far great overlap so tunes in at a higher RPM.  If 108 is the optimal
lobe center, then reducing the duration so the overlap is equivalent will
yield a cam that makes much better average power under the curve than the
114 LCA cam.

In "Be the Camshaft Expert" (July 2006 issue of Popular Hot Rodding),
David Vizard presented some rules of thumb for selecting cam specs based
upon what he's learned in developing a cam selection program.  An online
version of that article can be found here:

 http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/index.html

The program was reportedly 18 years in the making and uses data gathered
from several thousand cam tests.  The basic idea is that cam overlap sets
the RPM range in which an engine will best operate and the total overlap
is a function of the cam duration and lobe center angle (LCA).  If you
know the ideal LCA and the RPM range you wish to operate in, the duration
will fall out.  In the article, Vizard presents graphs of cubic inch
displacement (CID) per cylinder per inch of valve diameter versus ideal LCA.
The graphs are for inline valve heads with compression ratios between 9:1
and 11:1.  If canted valve heads are used, the ideal LCA is 2 degrees less.
The optimal LCA is also adjusted for compression ratios outside the assumed
range.  Once ideal LCA is known, you pick your desired overlap via
application:

 1. Street towing       10 to 40 degrees
 2. Regular street      30 to 60 degrees
 3. Street Performance  50 to 75 degrees
 4. Street/Strip        70 to 90 degrees
 5. Amateur Race        85 to 100 degrees
 6. Professional Race   95 to 115 degrees

Overlap is the period when both intake and exhaust valves are open and serves
to set the RPM range over which the cam will be best suited.  More overlap
means a rougher idle and poorer low end response due to reversion of the
exhaust charge into the intake plenum as well as loss of "effective"
compression ratio (compression is literally blown out the exhaust port at
low RPM).  Where you fall in the overlap range is a function of valve size
per cubic inch.  Big valves on a 302 use the low end, a 350 with typical size
valves use the mid-point, big inch small block or big block, use the right
hand side.  Given the small valve size of the Rover/Buick aluminum V8's,
we'd typically use the larger overlap value (right hand side).  Once LCA and
overlap are known, duration falls out of the equation.  Lift is determined
by the intake valve diameter.

In the article, Vizard presented the results of a test demonstrating the
importance of picking the right LCA:

 http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/photo_09.html
 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album15/LCA_comparison.jpg.html

Ideal LCA for that engine was 108 degrees.  Narrowing to 105 degrees made
similar power but had noticeably worse idle and low speed characteristics.
Widening to 111 degrees lost power.  Another LCA test was performed on a
302 Small-Block Ford and repeated on a stroked (347 CID) version of the same
engine:

 http://www.popularhotrodding.com/tech/0607phr_camshaft_basics/photo_12.html

 "When used in the 302, the 276/280 roller hydraulic cam on a 110 LCA proved
 optimal, as even a 1 degree change either way produced worse results. Using
 a SCAT stroker kit, this engine was stretched to 347 inches and re-tested
 with the original 110 LCA cam. The stroker kit really helped both power and
 torque. When the 110 LCA was replaced with a more appropriate 108 LCA cam,
 the output made a further jump to the tune of some 20 lb-ft and 20 hp.  The
 108 cam in the 347 gave as much in terms of idle and vacuum as did the 110
 LCA in the 302. Dozens of tests such as this show conclusively that the
 overlap and LCA--not the duration--are the first steps toward generating a
 cam spec."

At low speed, lots of overlap is bad as it hurts low end but overlap helps
as the RPM increases.  To a degree, you can offset overlap with static
compression.  Another point raised in the article is that, for most V8's with
reasonable heads, the ability to raise low speed torque with compression
increase holds to around 285 to 290 degrees (at lash point) of cam duration.
After that, drop off is faster than an increase in compression can recover.
In another article ("Compression Comprehension") about running up to 12:1
compression on pump gas, Vizard presented the results of a compression test:

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album15/CR_vs_low_speed_output.jpg.html

"When used in conjunction with a bigger cam, increased compression can
 work wonders for the entire curve. When a 265-degree cam (gray curve)
 was substituted for a 285-degree cam (blue curve), a substantial drop
 in low-speed output was seen. Raising the CR from 9:1 to 12:1 recovered
 almost all the lost low end and gave a further increase in top-end
 output"

I wrote a little computer program based upon the article.  The required
inputs for the simplified program are:

 bore diameter (in inches)
 crankshaft stroke (in inches)
 intake valve diameter (in inches)
 static compression ratio
 canted or inline valve heads
 desired overlap (picked from the ranges listed above)

Some results for various Rover/Buick combos are presented below.  Vizard's
cam selection program is not available to the general public but I know for
a fact it takes much more into consideration than the simplified rules
presented above.  A friend has run his program and it uses actual head flow
data, port size (length and cross-sectional areas), valve diameters, rocker
ratios, desired idle vacuum, compression, bore, stroke, fuel octane,
thermostat temperature, rod length and more.  Basically, it attempts to feed
the "air pump" in the most efficient manner, given the parameters entered.
What it doesn't do is tell you what ramp rates you need.  The recommendation
is to use the most aggressive ramp you can tolerate for your application.
However, more aggressive lobe shapes are noisier, wear more quickly and are
harder on valvetrain parts so that needs to be taken into consideration as
well.

The simplified program assumes you'll use the same lobe profile for intake
and exhaust.  There's an implicit assumption that the exhaust flow is
reasonable compared to the intake.  Vizard also suggests the rocker ratio
on exhaust is best kept 0.1 to 0.2 of a ratio lower than the intake ratio.
The exhaust is under higher pressure and blows down early in the lift cycle
plus the exhaust is less sensitive to valve acceleration than the intake but
is sensitive to duration.  I noticed in last year's Engine Masters Competition,
most of the entries were using shorter rocker ratios.  If an existing cam's
LCA is too wide, higher ratio rockers may increase output.  For rocker ratios
between 1.5 to 1.9, each 0.1 ratio increase on the intake, the LCA needs to
be spread by 0.75 to 1.  Be aware there are cases where the ideal lobe center
may be too narrow for acceptable street manners.  For instance, when stroking
an engine (keeping all other variables constant), Vizard suggests tightening
the LCA up by a degree for something like every 16 cubic inches increase in
displacement.  That will lead to very tight lobe centers which may not be
acceptable for certain applications.  For instance, an engine equipped with
mass-air EFI (which will measure reversion flow as if it were induction flow)
might not be too happy with 104 degree lobe centers.   Vizard's full-up
program allows you to specify idle vacuum to get around problems like that
but the simplified program doesn't have that sort of flexibility.

Another thing to be aware of is that narrow lobe separation angles require
an efficient exhaust with minimal back-pressure.  If you have a bunch of
back-pressure (from things like restrictive mufflers or headers that turn
down sharply at the exhaust port exit) it will hurt a narrow lobe separation
angle engine more than a wide one.  A quote from the article drives home this
point home:

 "Let's make one thing clear here: Big (but not excessive) overlap is a prime
  key to big power numbers, but only if your exhaust system sucks. Literally.
  If you have ever heard that an engine needs a little backpressure, you might
  want to ask yourself why an engine would want an exhaust system that literally
  pushes exhaust back into the combustion chamber rather than sucking it out.
  The simple answer is, it doesn't. If a big-overlap, big-cam engine has an
  exhaust system with any measurable backpressure, the price paid is a big drop
  in output."

If your exhaust system is restrictive, it may be wise to err on the side of
a wider LCA or shorter duration.

Since large valve heads tend to increase flow through high lift levels,
the lift recommended by Vizard's rules may be excessive for heads equipped
with large valves.  The recommendation is to use a lift consistent with your
reliability goal (higher lift wears valves, guides and seats more quickly).
However, for small valve heads, like our little Rover/Buick aluminum V8's,
the maximum lift is reasonable.  In the range of 2 valve pushrod V8's, our
Rovers are at the small valve diameter (per displacement) end of the spectrum
but, based upon my limited experience, the simplified program seems to give
pretty reasonable trends.  As a starting point, you could do worse.  Woody
Cooper has had a lot of experience with custom cams in Rovers of various
displacements and I believe his experience parallels Vizard's predictions.

Cam specs for Rover/Buick street performance assuming 75 degrees overlap
and 9:1 to 11:1 compression ratio:

 CID Bore x Stroke Intake   duration / LCA / Lift
                   Valve
                   Diameter
                   
 215 (3.50 x 2.8)  1.5      298 / 112 / 0.45 to 0.52
 219 (3.52 x 2.8)  1.5      298 / 111 / 0.45 to 0.52
 215 (3.50 x 2.8)  1.625    298 / 112 / 0.48 to 0.56
 266 (3.53 x 3.4)  1.5      288 / 107 / 0.45 to 0.52
 266 (3.53 x 3.4)  1.625    292 / 109 / 0.48 to 0.56
 292 (3.70 x 3.4)  1.625    288 / 107 / 0.48 to 0.56
 292 (3.70 x 3.4)  1.775    292 / 109 / 0.53 to 0.62
 297 (3.73 x 3.4)  1.775    292 / 108 / 0.53 to 0.62

Note that the durations used here are seat-to-seat duration (similar to
advertised or SAE duration, not duration at 0.050").

Okay, so that's the theory. Here's some of the practice side from an
engine builder friend of mine...

If you set up a cam on blocks or centers and use a lifter jig, or plot
it out on paper, it quickly becomes apparent that the range of actual
lobe profiles is sharply limited. For flat tappet cams, the diameter of
the lifter or the length and curvature of the finger follower defines
the limits of possible profiles. Once your pressure line gets to the
edge of the follower, there's no more to be had. For rollers, the
diameter of the roller is your limiting factor. Eventually the pressure
line reaches the height of the axle, and spits the roller off to the side.

That's geometry. It does make a difference; that's why flat tappet
racing lobes are specified by lifter diameter, and why rollers go to
inverted flanks.

Then you need ramps to take up the slack on opening, and to keep from
pounding things on closing. That further restricts allowable profiles.

Then you come to the big real-world part - wear. For a flat tappet,
wear is pretty much a function of load at the pressure line. That's why
Detroit cams are all so wimpy. They had to last 75,000 or more miles
without wearing to the point where they had to be replaced. For
hydraulic rollers, oil viscosity and pressure are your main limits,
where leakdown starts to change the valve motion significantly from the
lobe motion. And remember, that's assuming a 10 year old car that still
has the oil it left the factory with, in a worst-case service condition,
like pulling a camping trailer in New Mexico in the summer.

For a "performance" cam, longevity is sacrificed first. You can load
the cam more heavily, and shorten the ramps, and pick up lots of "free"
power by kicking the valves open faster and closing them sooner.
Competition Cams is infamous for this; some of their more aggressive
street cams seldom saw more than 20,000 miles before rounding off lobes
or hollowing lifter bases. They *did* perform as advertised. Note
that Comp recommends armor-faced lifters for flat tappet lobes that
require heavy spring rates.

For "street" cams, you have to assume the stock valve springs are being
used, because a largish fraction of your customers *will* insist on
running them. Getting more area under the curve with stock springs is
a damned good trick; you can whack it off the seat, but you have to stop
lifting early and carefully to keep the valvetrain together at max lift,
and you have to set the valve down carefully to keep it from bouncing.

Drag cams are quite specialized now, which is why you see the lobes
separated from circle track stuff. Longevity on a cutting-edge drag cam
is often less than a dozen runs for a flat tappet. For solid rollers,
lifter failure happens first.

Power is cheap. Longevity is what costs the big money.

Crane and Isky like to talk about stepped lobes to handle harmonic
motion of the valvetrain bits, and other crap like that. It's just
marketing; on the dial indicator, it's all a smooth curve.

What's creepy is to mike a brand new cam, and find .005" difference in
lobe height from smallest to largest. Kind of makes me laugh at Crane,
which claims accuracy down to *millionths* when tossing cams into the
grinder...

Extended exhaust duration only adds overlap, with its attendant idle
and emissions problems. All-out racers use long exhaust durations for
scavenging, but that ruins your fuel economy on the street. It's primarily
a drag race trick to keep the power from dropping off quickly after power
peak. On the street, a symmetrical profile or even a short exhaust will
run just as well and with a lot more tractability. On the street, extended
exhaust profiles date back to the 15-psi-backpressure old-style catalytic
convertor days; they are obsolete.

Overlap creates a lot of internal EGR during cruise which is great for fuel
economy if the spark is advanced enough. In the BMW world, intake and
exhaust cam profiles are either the same, or the intake gets the bigger cam.
Independent runner intake manifold can withstand a lot more overlap without
trashing the low speed torque and tractability than a standard plenum carb
intake.

Dan Jones

One of these days I'm gonna succeed in convincing Dan to write articles for BritishV8 instead of (or in-addition-to) putting so much effort and information into message-board posts. They'd be such a valuable reference and they'd probably reach so many more people. (Tables and charts would also be easier to integrate.)

Awesome and thought provoking information!

A bit overwhelming though, for non-motorheads like me...

An interesting feature I wanted to also mention is the lobe lift at .34 is just about as big as it looked like you could make it without making the camshaft weak. As it is, the back side of the lobe is almost even with the main shaft of the cam and in some places looks like it is at the diameter of the main shaft.

I'm starting to reconsider running E85 again. Do you think there is any difference in cams for that? Probably not but interesting to thing about. I think after I CC the heads and get a clear understanding of my actual CR I'll decide. I figure if I'm under 11:1 gasoline. If I'm over that I might consider E85 again. I initially threw out the idea because of the expense in converting a carb for it but the are getting less expensive now.

Just tossing in wrenches. LOL!

Good stuff Dan. It's really great to have someone around who ponders and really understands these things. But what happens when you add boost? I mean just from reading your post and having not yet followed the links...(I will, count on that) it would almost sound like I'd be better off to just stick with a stock cam. Here I am thinking that it'd be an advantage to help the exhaust side since the intake is getting a boost (literally) and you up and say extended duration on the exhaust ain't all that great shakes.

But I'm looking for the practical solution. Something to let me take advantage of the Scat rods, Venolia pistons, CC springs and Eaton blower but keep the economy and driveability of the 10 to 11:1 CR. But I don't want to make a study of it, just want to find a decent bump stick.

340 Buick, stock '64 300 heads.

Jim

Jim I would try calling Woody: 1-508-880-5448 OR email him:  Woody@TheWedgeshop.com

He's got a lot of practical cam experience since the late sixties. He might have a good thought or two on it or he may know a good resource.

Whatever your findings, post'em. I'd be really interested in knowing. Not for my project but I just love to know why things work the way they do.

Thanks for staying in the thread.

> One of these days I'm gonna succeed in convincing Dan to
> write articles for BritishV8 instead of (or in-addition-to)
> putting so much effort and information into message-board
> posts. They'd be such a valuable reference and they'd
> probably reach so many more people. (Tables and charts
> would also be easier to integrate.)

One of these days I'll get around to finishing one of those
articles but things are very busy at the moment.  Outfitting
the new shop and running the dyno program are taking up
most of my free time.

Dan Jones

I emailed Woody and he is going to see what he can come up with. He feels the challenge might be to get 7 grand out of the stock alloy 300 heads.

Incidentally Nick, have you checked your rod to cam clearance? I'm out of space. I'll have to grind the shoulders of the rods to keep from hitting the cam lobes, they just graze with the stock cam. I think that's going to limit my lift to very near stock. I don't think Woody will be happy. Wonder how much clearance you need? I'd think about .020" would do it.

Jim

Interesting! I am about to start assembling the bottom end. I will be careful and post what I find. I figure I'm about three weeks away from that.

Thanks Jim!

Glad to help.
I wish I had some input on what is considered adequate clearance between the cam and the rods. I'm thinking .020-.030" would do it.

I could get that by reducing the base circle of my cam and get a more performance oriented grind in the process. Currently I have a 1.175" base circle, 1.020" minor diameter and 1,425" lobe for .250" lift (.400 at the valve) so if I reduced the lobe height by .030" to get clearance and then reduced the base circle to get lift back it would seem I could go as high as .490" at the valves and possibly even get a little more duration. Does this make sense?

Jim

The Chevy stroker guys say .050". The BIG stroke engines go with .080" due to crankshaft flex. I would use the smaller base circle cam as a last resort.

Thanks Carl, that really helps. I do think we're looking at last resorts here, the only other option is to mill down the shoulders of the rods and with them already finely balanced I just hate to do that, plus there isn't a whole lot to be gained there before getting into the threads. I may end up doing both though.

Disadvantages of a reduced base circle? Can't really be a strength thing since the weak points are the minor diameter and I wouldn't be changing that. It used to be pretty common practice to regrind cams. Even at .050" clearance I think there's still room for .500" lift and I don't expect to need more than that.

Jim

> Here I am thinking that it'd be an advantage to help the exhaust side
> since the intake is getting a boost (literally) and you up and say
> extended duration on the exhaust ain't all that great shakes.

Vizard's cam rules apply to normally aspirated engines.
Different rules apply to supercharged engines.

> But I'm looking for the practical solution. Something to let me take
> advantage of the Scat rods, Venolia pistons, CC springs and Eaton
> blower but keep the economy and driveability of the 10 to 11:1 CR.

You've got some mis-matched parts there that make specifying a cam
difficult.  You're trying to vent a 340 cubic inch engine plus
boost through a 1.3" exhaust valve.  You're limiting lobe lift
bacause of a rod clearance issue and your trying to run boost on
top of high compression on pump gas.  

> Disadvantages of a reduced base circle?

Might be worth a call to Erson (Steve Tanzi) if Woody doesn't have
a call in for you already.  If the cam core has been heat-treated
already, there is a limit to how far you can grind before breaking
through the heat treat.

Dan Jones

I take it you disapprove. I don't mind that, but perhaps it would help a bit if you better understood where I'm coming from. To start with I really don't need more power than I have right now with the 215. I have other goals in mind. But since it *is* a 350 (340 + .050") I might as well bump it up a little. Did I state the power goal? 400hp is not a lot to ask from a 350, even normally aspirated. Why do I want it to turn 7 grand? Because I *like* it. Not because I expect a big power boost above 5000. Why am I putting a blower on it? To overcome the restriction of those small valves you mentioned. Why am I using such small valves? Two reasons, money and money. Gas and machine work. The high compression is also for the first of those two reasons, plus low end torque. The intercooler is for the low octane fuel. (Who said I was going to run regular in it? That would be a switch.) Also, I want a cast iron block, and I want to put a Buick 340 in my MGB.

This car may very well never see another drag strip, but it *will* be taking on the back roads of KY and West By God Virginny. For that I don't need as much power as I have now. Heck even without the blower this engine might blow the doors off the 215.

I do appreciate your comments. I would appreciate them even more if they were more to the point. I know quite well this is a challenging application. Convention has been thrown out the window. I'm on a quest here to get what *I* want and that's a long ways from the mainstream.

Jim

FYI..
 Harold Brookshire  former owner of Ultradyne and designer  for Reed, Lunati, and others offered up this cam info.


I have a very reliable solid lifter cam of the following specs:

.020 282/292
.050 248/255
.200 155/162
valve lift, 1.6s
.536"/.551"
LCA as wanted...

This would be a healthy cam in an engine of that size...
It has gone over 100,000 miles in street SBCs, and needs the valves adjusted at least once a year.....
I also have much more aggressive solid lifter cam lobes.
The lowest lifts I have with rollers are about .550" with 1.5s.

Cores for the Buick 215/300/340 are available, but from a supplier.
 It will take 5 to 7 working days to have in the shop.
Mike, who was my shop foreman at UltraDyne for 19 years, and who now is shop foreman and Landis operator at Lunati, reminded me that the cores do not have a lot of meat on them, and the cam will need to be ground straight-up, with no advance.
Costs? Around $220 right now.
If I can help, please let me know......

Harold Brookshire

662-562-4933

Interesting. I don't really want to run a solid lifter cam because I have no provision for lash adjustment. Lift will have to be limited to .500 on a 1.020" base circle to leave .050" rod clearance. The cam used for inspection has a 109* LCA and .250" lift at the lobe. (.400 at the valve).

I would like to keep the intake lobe reasonably mild for good driveability and economy and run an agressive exhaust lobe to allow better evacuation of the cylinder under boost.

Jim

QUESTION:  (esp to Nick)

What have you done to the Heads to improve flow?

The airflow of rover heads needs to be improved before ANY high lift cam makes a difference.   This is why the "stock" cam works so well... it's matched to the head ports.   Bolting a higher lift, longer duration cam into "stock" heads has been shown on the dyno to make little, if any, difference!

I'd make sure the heads can flow for those larger valves.  You'd want something better than 160 cfm (intake) and 130 cfm (exh) for those size valves at that lift. (Those are 28" merc. readings.)  

Just bolting a lot of "bigger" parts on isn't going to make any difference if you haven't changed the flow characteristics of those heads.   They have always been the limiting factor to performance of that motor....

$.02

> What have you done to the Heads to improve flow?
> I'd make sure the heads can flow for those larger valves. You'd want
> something better than 160 cfm (intake) and 130 cfm (exh) for those
> size valves at that lift. (Those are 28" merc. readings.)

Switched to 1964 Buick 300 heads, ported with larger seats and valves.
CFM is just under 200 on the intake and a little over 150 on the exhaust.

> The airflow of rover heads needs to be improved before ANY high lift cam
> makes a difference.  Bolting a higher lift, longer duration cam into
> "stock" heads has been shown on the dyno to make little, if any, difference!

Some dyno results below which do show HP increases.  As with any
engine it's the incremental contributions of the combination that
make power.

> This is why the "stock" cam works so well... it's matched to the head
> ports.

I never found the stock cam to be particularly good.  HP is directly
proportional to RPM.  Cam duration drives RPM.  The stock cam has too
little duration to support much in the way of RPM.

> Just bolting a lot of "bigger" parts on isn't going to make any
> difference if you haven't changed the flow characteristics of those
> heads. They have always been the limiting factor to performance of
> that motor....

Way back in 1961, Hot Rod Magazine presented the results of dyno
testing on both the Olds and Buick 215's.  Starting with a 2 barrel
Buick that dyno'd at 136 HP, they ended up with a high compression
2 x 2 bbl engine that made 233 HP.  Changing from the stock cam to
an Isky E2 cam, it went from 177 to 215 HP (Hedman headers and larger
carbs were installed at the same time).  In the testing sequence
of the Olds, they went from a stock cam to an Isky E-4 and went from
172 to 194 HP.  Head porting on the Buick picked up 7 HP.

More recently, Ted at T.S. Imports provided the results of a dyno test
on a Rover 3.5L and the results were published in a 1995 British Car
article "Improving the TR8 & Buying a TR8", Dave Destler, 1995 British
Car, pp 35, 47-48.  The "V8 on the Dyno" sidebar gives the relevent
information:
 
  conducted by Ted Schumaker of TS Imported
  rebuilt 3.5L Rover V8
  stock bore and stroke
  unmodified cylinder heads
  22 lbs steel flywheel (stock is 32)
  Tri-Y TR8 headers
  10.5:1 compresson cast aluminum pistons
  Isky 264 hydraulic flat tappet camshaft

  Run 1:
  Holley 390 carb, vacuum secondaries, #51 primaries, #58 secondaries, Offy
  JWR dual port manifold, 22 degrees advance, vacuum advance disconnected

   RPM   Torque  HP
   4000   211    161
   4500   210    180
   5000   205    195
   5500   189    198
   5700   189    205
   5900   181    204
  Run 2:
  Holley double pumper 390 carb, mechanical secondaries, #62 secondary jets,
  Offy/JWR dual port manifold, 28 degrees advance, vacuum advance disconnected

   RPM   Torque  HP
   4000   ---    ---
   4500   219    187
   5000   210    200
   5500   197    206
   5700   191    207
   5900   182    204

A later test was run with an Edelbrock Performer Rover intake and and the
results published in the MGB V-8 Newsletter, Issue III, Vol. I:

  Run 3:
  Edelbrock Performer Rover dual plane manifold, 30 degrees advance

   RPM   Torque  HP
   4000   232    177
   4500   230    197
   5000   222    212
   5500   215    226
   5700   217    235
   5900   207    232

Dan Jones

> Head porting on the Buick picked up 7 HP.

I was surprised the head porting didn't pick up more.
I suspect the dual plane intake manifold was at fault.
If the intake manifold is more restictive than the
cylinder, which is usually the case with dual plane
intake manifolds, then you won't realize the cylinder
head's potential.

Dan Jones

Thanks for picking up the ball on this one, Dan. The answer is yes 300 heads larger valves and porting. Right now I have my heads back in the shop again to have beehive springs from CompCams installed. I'm also considering taking the heads to the next level from a port standpoint. My engine machine shop has a porter with a good machine but it couldn't hurt to toss in a couple pointers on specifics for the porting.

Do you have diagrams for where the most flow yield is to be had from the 300 heads, Dan? Where should I tell my guy to focus?

BTW here's a link to my head mod page:

http://www.cardomain.com/ride/2357894/2

I think the 300 heads have 52 cc chambers as well so a different piston might be needed. Olds 4 bbl and Jetfire heads should be the same as the Buick and Rover, while I think the 300's are close to the same as the 2bbl Olds.

Nick, are those behives going on 300 heads? Since you are using them, could you ask if they will fit the Olds heads also? Lighter retainers should be a plus.

Jim

OH one more thing. I'm planning on going with the Harcourt single plane. It's got a pretty big plenum. The middle ports are going to have the best access to the carb. I'm also concerned about the fuel ratio imbalance between 7 and 2 because of the firing order. because 5-7 fire in order, fluid dynamic inertia will favor 7 and that has to reverse to get to 2.

What do you think? Do I need to insert dams at 7 or something? Or just let it go? I did find a dyno place that will tune on the engine dyno with wideband at each cylinder...

I'm not sure what the difference is in the pocket size for the Olds head. I've only worked on the 300 head. From what I understand the springs I used for that setup with a mildly aggressive cam were for a SBC. What is the Pocket dia for the Olds?

The Buick pocket dia. will take 1.260" dia. springs. I'm ordering CompCams #: 26915 for the LS1. It's seat pressure is 105 lbs. and 290ish lbs. open. It's dia. is 1.290" but I'm pretty sure I can have 30 thou machined open. The spring height is 1.7 for my cam choice.

The comparable standard spring would be TA_1436 from TA performance. Here's a link with details.

http://www.taperformance.com/products.asp?cat=408

Sorry I couldn't find any reference to the spring dia for the Olds. Post it if you can, Jim.

> Do you have diagrams for where the most flow yield is to be had from the 300 heads,
> Dan? Where should I tell my guy to focus?

No diagrams but take a look at the close-ups here:

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Buick_300_ported_chamber_closeup.jpg.html
 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Buick_300_ported_intake_port_closeup.jpg.html
 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Buick_300_ported_exhaust_port_closeup.jpg.html

I'm not sure if you have the option to view the full resolution like I do but try this link:

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Buick_300_ported_chamber_closeup.jpg.html?g2_imageViewsIndex=1

If he's ported Buick V6 heads before, the Buick 300 responds to similar work.  The bowl area and short side
radius are the areas to pay the most attention.  I'll compare a stock Buick 300 head to my ported heads
this weekend to see if I can come up with anything more specific.

Dan Jones

Thanks Dan. I'll pass these on to my porting guy. I'll also mention the info about the Buick v6 heads.

Nick I'm sorry to say I can't answer that question. Heads from the blower motor left today and the only other Olds heads I have have been converted to straight springs. I do know the Buick 215 and 300 can use the same springs and suspect the base of the Olds spring is the same, but I have no way of knowing for sure.

Jim

We took a good look at the cross section of the head I sawed up today.. the intake looks pretty cut and dry but the exhaust side is pretty restrictive.. we welded up the port floor and raised the roof.. man does that ever straighten it out.... we will look into claying up the floor on a full, good port ,and raising the roof to see what kind of gains we get on the bench.. the will essentially straighten out the dogleg..

> We took a good look at the cross section of the head I sawed up today..
> the intake looks pretty cut and dry but the exhaust side is pretty restrictive..
> we welded up the port floor and raised the roof.. man does that ever straighten
> it out.... we will look into claying up the floor on a full, good port, and
> raising the roof to see what kind of gains we get on the bench.. the will
> essentially straighten out the dogleg..

That should help a bunch.  Vizard did something like that on a Rover head:

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Vizard_Rover_heads_exhaust.jpg.html

He also welded up the intake ports (on top of the casting as well as the port floor):

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Vizard_Rover_heads_intake.jpg.html

Valve sizes were increased and a chanmbers welded and re-worked:

 http://www.bacomatic.org/gallery2/v/hidden/dan/dan-cars/album10/album12/Vizard_Rover_heads_valves.jpg.html

Will you also be welding up the intakes?  On my ported 1964 Buick 300 aluminum heads,
we used Buick V6 Stage 1 valves from Ferrea.  The intake diameter was 1.775" and the
exhaust 1.5" (stock is 1.625" and 1.312", respectively).  With those valves and no
weld work on the exhaust, the exhaust flowed around 75% of the intake flow:

  Lift    I     E     E/I
  0.100   66    47    71.2
  0.150   99    82    82.8
  0.200  129   104    80.6      
  0.250  155   119    76.8
  0.300  174   130    74.7      
  0.350  187   139    74.3
  0.400  191   146    76.4      
  0.450  194   150    77.3
  0.500  196   152    77.6      
  0.550  200   153    76.5
  0.600  200   153    76.5      

Increasing the exhaust to intake flow ratio beyond that value generally doesn't
make any additional power but may increase fuel economy somewhat.  Higher
compression ratios (13:1) tend to favor a lower ratio.  Given my results, it
appears that increasing the intake valve diameter at the expense of the exhaust
might be beneficial, assuming there are no shrouding problems.   If you do end
up with higher exhaust ratios, you may want to consider a custom cam with
shorter duration and lift on the exhaust side.

Dan Jones

OK so I got a minor problem. The Iron Duke intake isn't long enough for the .544 lift of the cool Erson cam I got. He's looking for a valve that will be long enough to fit without boring the guide out. That way we can retain the smaller dia. 5mm stem for flow. The 231 valve head is too big at 1.8" dia. but the stem works. We could go with the standard buick v6 valve but we'd have to bore out the guide.

It would be ideal if we could end up with a total length of 4.730"

This is all to use beehive springs. I may have to revert to the standard springs. Thanks in advance for any input.

Well it was just a pipedream but you never know. Not all bad though I've officially converted to the larger dia. stemed late Buick V6 valves like Dan. I'm using Comp Cams beehive springs #: 26915. Sweet!

Thanks for all the support everybody. Holiday wishes to all.

OH, Tony, I'm saving all my parts: Valves, Springs, Retainers, Keys, Cam, etc.
Were you interested in using them?

Nic
Ill probably go the Stage 1 valve route as well.. Im also most likely going to need clearance for .580  lift..

I had thought about saving the cam for the Olds engine but I just laid out some money for Chevelle repairs.. Ive got to keep the "done" one running.. I didnt go racing once in 2008! and Im starting to suffer withdrawal! LOL
So if anyone else is interested.. this is all the stuff from the Dan Lagrou 300 head upgrade..it should work real well for a pump gas  street bruiser!

Damn, I'm Iate for a party now!

Hi ,

I read with interest the advice given on cam selection and I wonder if anyone can assist with this one.

my current cam is 263 duration 47 overlap 108 lobe center separation and a low lift of .38 (rocker ratio 1.6) coupled to low compression pistons(fish bowls) in a 4.4 litre Leyland terrier(p76 truck engine)
with heavier crankshaft weights.
car is a triumph stag ..Green of course(reg is Fastag) and has 2.78 diff with alloy housing for lighness. has 5 speed supra box.

so  reasonably light for a car but gearing is hard with a tall first I  think on the supra box compared with the rover 5sp as well.

I am rebuilding with higher compression around 10:1 mayby 9.5 ish for fuel type.

This is an every day car and  I'd just like to use the stage 3 head's capacity more. they have the valves from the newer discovery in them so.. 1mm larger or so.

I've been reading D. hardcastle..both books and vizard "how to build hp"

not racing obviously but how far can I go as the cam was first put before I opened up the inlet with open plenum manifold and
4 barrel 465 holley instead of stock p76 manifold with 2brl holley.

your thoughts on a cam selection guys ?

this is a great site..hope I can assist as well as getting assistance.
Rod

Dan.

I f you have time to comment I would love to hear your opinion on a new engine I have recently built and installed in my MGB GT which is probably around 2300lbs weight and runs a rover LT77 gearbox with .78/1  5 th gear and 3.08/1 final drive.

The engine spec is based on a 3.9 block which is fitted with a 3.03 stroke crank 5.85" rods and Keith Black hypereutectic chevy 305 flat top pistons for a bore size of 3.736" for a capacity of 4.35 litres approx 265 CI with a relatively short stroke

I have fitted Buick 300 heads with the faces machined 40 thou to reduce chamber volume to approx 48cc and fitted 1.63" Inlet valves and 1.4" exhaust valve both with waisted stems, the heads have been modified to open up the seats to the larger valves sizes and the bowls opened up to match with the guides bulleted to the same extent as your 300 heads. I purposely left the port runners as cast apart fron cleaning up a few rought bits of casting to maintain suspension of the fuel at lower RPM's

The decks were also machined 40 thou. to give a compression ratio in the region of 9.4/1 with composite gaskets, the pistons have not been pocket for the Buick rover valve position so erred on the safe side for as didn't wan't the valves kissing the pistons but would like a bit more static compression to offset the overlap as I'm sure that only 9.4/1 is going to cost me power, tin gaskets would get me in the region of 10/1 which would be nice.

The cam I selected bearing in mind that the use of the car will 90% road is a Crower 50232 and the induction system is currently an Edelbrock 500 on a performer manifold, I haven't as yet re-jetted the carb from the 3.5 settings but it does run reasonably apart from being a pig to start from cold.

Current primaries are 1441 rods and 1421 jets with the secondaries as stock so probably a little lean but it will run cleanly down to approx 1500 RPM in 4th gear but doesn't like it if you give a bit of throttle and you need to drop it down a gear or two if you want to accelerate but I'm obviously not using WOT at the moment. but it has had some short burst of hard acceleration to bed in the rings, and pulls very strongly and clean from around 2000 RPM and really wakes up at around 3000RPM.

I am also going to switch over to EFI in the near future and have the hardware from a Hotwire system and a Megasquirt ECU to control fuelling and ignition, the engine has a trigger wheel and sensor in place, and bungs in the primaries for Lamba sensors so only plumbing and electrical left to do after i've mdded the inlet to mastch the Buick ports.

You may not remember, but you gave me some good advice on setting up the carb for the original 3.5 engine for which i am grateful.

I think that the spec of the new engine is in the right ballpark but any commnts and advice would be gratefully recieved.

Regards,

Kevin Jackson. UK.

Dan

PS. Do you happen to know the actual valve opening and closing numbers for the Crower 50232 cam as the card that comes with the cam only gives figures for dialling in the cam.

Kevin.

http://www.crower.com/misc/cam_spec/cam_finder.php?part_num=50232&x=25&y=9

Graham,

Yes thats the card I have, but the way the valve periods are expressed seem a little strange and nothing like the sort of figures you normally see for a performance cam.

Kevin.

Kevin,
     For specific cam tech assistance, I'd suggest phoning or emailing them - worth a try!
http://www.crower.com/misc/contact.shtml
  Graham

Graham,

Thanks for the suggestion but tried that, they just mailed me back a copy of the card!

If you look at the fiures given you'll see what I mean, certainly don't understand the minus figures.

Kevin.

> I am rebuilding with higher compression around 10:1 mayby 9.5 ish for fuel type.

Run the 10:1 if you can.  The higher compression will offset the low
end lost by the increased cam overlap.

> they have the valves from the newer discovery in them so.. 1mm larger or so.

The long stroke (3.5"), small bore (3.5") P76 has a rather tight ideal LCA,
something in the 107 degrees range.  For street performance, your looking
at around 60 degrees overlap.  That works out to a seat duration around
275 degrees (215 degrees at 0.050" lift) with lift of 0.450+".  You may
not find an off-the-shelf Rover cam with 107 LCA.  You're probably looking
at 108 degrees.  The closest I can find is a custom Isky 264 grind that
only Ted Schumacher carries at TSI Imported Automotive.  Woody Cooper at
the Wedge Shop can also work you up a custom using Erson lobes that will
work well.

Dan Jones

I ran the numbers for:

 3.736" bore
 3.03" stroke,
 1.63" intake valve diameter
 9.4 to 10.4:1 compression
 lightweight, gears

for overlaps of 70 to 80 degrees:

 70 degrees overlap 287 degrees seat duration, 109 degrees LCA, 0.488"+
 80 degrees overlap 297 degrees seat duration, 109 degrees LCA, 0.488"+

The only off-the-shelf cams I'm familiar with that have 109 LCA's are
the Isky 270 and 282:

 Isky 270    270/270  216/216 .470/.470  109  2000-6000
 Isky 282    282/282  224/224 .467/.467  109  2500-6500

Of those two, the Isky 282 is the better choice for your engine.
If I was doing a custom, I'd probably look at the Erson Hiflow AH
or 1H lobes on a 109 LCA.  You might call oe email Woody Cooper
to see what he'd recommend.

Here's a list of Erson's hydraulic lobes:

            .050 adv  lobe   1.6:1
            dur  dur  lift   lift

RV5H        202  274  0.273  0.437
RV10H       208  280  0.280  0.448
RV15H       214  288  0.288  0.461
TQ20H       214  292  0.299  0.478
TQ30H       226  310  0.310  0.496

Hiflow AH   220  284  0.315  0.504
Hiflow IH   228  296  0.315  0.504
Hiflow IIH  235  306  0.315  0.504
Hiflow IIIH 240  316  0.315  0.504

> The cam I selected bearing in mind that the use of the car will 90% road is a Crower 50232

The lobe centers of the Crower 50232 are too wide for your application.

> PS. Do you happen to know the actual valve opening and closing numbers for the
> Crower 50232 cam as the card that comes with the cam only gives figures for
> dialling in the cam.

I do not.   You  need to contact Crower and ask for the SAE timing events.
The ones on the card are at 0.050" lift.  You need them at 0.004" SAE lift.

Dan Jones

Dan,

Many thanks again for your excellent advice.

So with the 112 LCA how is that affecting the characteristics and power being produced by the engine?

The science of cam design is obviously very complex and not just down to capacity but all the factors such as the bore to stroke ratio, rod length, and valve size need taking into consideration.

I will drop Crower another e-mail to see if they will provide the SAE events as suggested, just curious to see how they compare to other performance cams for the Rover engine.

The SAE lift figures you mentioned of .050" and .004" is that correct as they seem very low figures to me but I'm probably wrong.

Kevin.

Quotemy current cam is 263 duration 47 overlap 108 lobe center separation and a low lift of .38 (rocker ratio 1.6) coupled to low compression pistons(fish bowls) in a 4.4 litre Leyland terrier(p76 truck engine)
with heavier crankshaft weights. The car is a triumph stag ..Green of course(reg is Fastag) and has 2.78 diff with alloy housing for lighness. has 5 speed supra box.

This is an every day car and I'd just like to use the stage 3 head's capacity more. they have the valves from the newer discovery in them so.. 1mm larger or so. Not racing obviously but how far can I go as the cam was first put before I opened up the inlet with open plenum manifold and a 4 barrel 465 holley instead of stock p76 manifold with 2brl holley.

your thoughts on a cam selection guys ?

this is a great site..hope I can assist as well as getting assistance.
Rod

Hey Rod. Welcome to the board. Sorry I didn't see your post earlier.

The cam you have selected sounds pretty good from a LCA stand point. You are right that it isn't taking advantage of your stage 3 heads though. The heavier crankshaft weights probably limit your redline a bit so maybe going with a bit more lift, like another 100 thou or so. The duration is short too but may be ok for the lower redline. You are right about the car being light so you can get away with some sacrifice on the low end. You also have that steeper low gear to get you going so maybe some low end sacrifices could yield something in the 5k rpm range.

Any suggestions there, Dan? Or somebody?

I finally got my cam from Camcraft so I thought I'd post the specs.
262/262 adv. duration
212/212 @ .050
.436/.436 lift
112* lobe separation
110/114 centerline
Now the part that I need a chart for:
In. open -4 btdc close 36 abdc
Ex open 40 bbdc close -8 atdc

I'm not sure why those two minus signs are in there, maybe it will make more sense if I could chart it out. I can't correlate those numbers to the ones produced by Pat Kelley's DCR calculator. But, I'm ending up with a 9.67 static compression, .045" quench. and 7.9 DCR based on Pat's calculator. That looks about right for pump gas.

Jim

Hi NixVegaGT, thanks for replying..

-Quote-
[Hey Rod. Welcome to the board. Sorry I didn't see your post earlier.

The cam you have selected sounds pretty good from a LCA stand point. You are right that it isn't taking advantage of your stage 3 heads though. The heavier crankshaft weights probably limit your redline a bit so maybe going with a bit more lift, like another 100 thou or so. The duration is short too but may be ok for the lower redline. You are right about the car being light so you can get away with some sacrifice on the low end. You also have that steeper low gear to get you going so maybe some low end sacrifices could yield something in the 5k rpm range.

Any suggestions there, Dan? Or somebody?]

I can't see a quote option on this so I've pasted your's in here. I take your point on the lift being low and aim to correct this.
I'm currently having the bottom end of the motor redone and the old 8.0 compression pistons are being replaced with 9.7, which oughta lift it a bit. I gather that cams go from 0.43 valve lift  up to  0.50 with extreme being 0.53.
given that the cam I quoted was stuffe, the highest lobe lift reading was .237inlet/.191out, which baffles me. This only makes it 0.38 at the valve, assuming 1.6 rocker ratio of the p76 stud rockers. I can see the reason for the low inlet, the initial engine rebuilders may have wanted to increase signal at the holley jets/boosters and perhaps a small valve opening was meant to increase gas speed on the inlet at the expense of chamber filling ??  but to have a small apperture on the exhaust...seems strange.

so once again..anyone have a cam choice suggestion..
2.78 diff  1100kg car    2100rpm at 60mph

I've heard that anything below 275 will give smooth idle , which does not really both me as long as the torque is there  for a 2.78 diff and supra 5 speed just above idle.  update on the old cam, its LCA was actually 108.9 nolt 108 which fits the 108-110 category at least.
cam choice guys ..your thoughts. ??

My aim is to lift it a bit to make use of the stage 3 heads, but not to lose the torque.
old cam was 20/60/56/27 but that was with 8.0 compression, now going to 9.7 but keeping diff ratio at 2.78.

Last week I finally got down to re-calibrating the Edelbrock 500 carb and got the engine running very well which enabled me to have a proper drive on the road.

The 4.35L engine will now idle smoothly at 1000 RPM which surpriised me, and on the road will run smoothly right down to 35 MPH at approx 1500 RPM in direct 4th gear with the 3.08 diff, and will even pull away without hesistation without changing down which suprised me even more, as I had been advised that the idle would be fairly lumpy and probably would not pull cleanly until about 2000 RPM. Bear in mind that I am also using modified big valve Buick 300 alloy heads which have much larger port runners than the Buick 215 or Rover heads and are probably the equivalent of stage 3 with the 1.63" In. and 1.4" Ex. valves.

Drop it down to second gear and it just wants to scream through the rev range, I'm still running in so am being a bit careful and not using full throttle or revs but the initial findings seem to be very encouraging, will obviously know more once i've got a few more miles on the engine and changed the oil for the good stuff and fiited a new filter.

I appreciate that I may be sacrificing some ultimate top end power but the general drivability is important to me as I live in a high density traffic environment and have to drive a few miles to get out into the country, so it seems that the Crower 50232 may not have been such a bad choice after all.

I'm hoping to have it run in in the next couple of weeks and will run it on a drag strip on June 14th to see how it really performs. and will report back.

Kevin.

Sounds great Kevin! On the break-in Dale Spooner advised me that the motor needs to have a load applied to it in order to break in the rings properly, so don't baby it too much. Fantastic to hear you have it running so well.

Jim

Jim,

Thanks, it gave me nightmares wondering how I was going to bed the cam in to accepted procedures which is the opposite of what you need to do to bed in the rings.

Unless you can do the break in on an engine dyno set to load, you have to compromise to some extent, once it first fired up and checked for any leaks I got it out on the road and subjected the engine to acceleration and  decelleration whilst keeping the revs over 2000 RPM seemed the only way to do it,time will tell.

Took the car for a run this afternoon and one small problem has emerged, now I have the idle down to 1000 RPM one lifter is bleeding down and tapping until you raise the revs a bit, I thinking I may not have enough preload on it and as I have adjustable pushrods I was thinking of just identifying the noisy lifter I know it's cylinder 2 or 4 and giving it a little more pe-load..

Kevin.

Yeah, we've been talking about preload a lot lately. Since yours are adjustable, how much preload did you dial in, if I might ask?

Jim

Jim.

I used a 25 thou bit of welding wire pushed in between the lifter piston and circlip and then just wound the pushrod out until the tension on the wire was released then tightened the lock nut, this was done with the lifter on the base circle of the camshaft.

Either I have one faulty lifter (Crane Hi Rev) or I have got one a bit too loose allowing the lifter to bleed down which is what I understand happens if you have insufficient preload.

Kevin

That makes sense. Middle of the range would be about .040" so you're probably just a little light. Another half turn or so should get you there.

Jim

Quoteold cam was 20/60/56/27 but that was with 8.0 compression

Rod,

The DCR at 6.42:1 with this timing is terrible! I can see why you wanted a change. How did it idle? It couldn't have been great. This cam actually isn't bad for your new compession. The DCR is still pretty low at 7.7:1 but better.

Quoteso once again..anyone have a cam choice suggestion..
2.78 diff 1100kg car 2100rpm at 60mph

If this cam had more lift maybe. A similar cam would be the Isky 262. It's about the same duration with a larger 0.445" lift. I'm not certain what the actual valve timing is though. If it's close to your current valve timing than it's decent. That's my best guess.

Anybody else?

Hello V8ians, I'm pancakeing on, cams options. Anyone have suggested data for "direct cam on 4 valve" applications? I'm preparing to build ,4 cams-1 motor. I would like them to be optimum. Scenario:Lotus 907 heads with O.S.valves, I.R. runners,E-85 fuel, 3.73" bore/3.3" stroke= 4.6L. Lotsa rpm, 8k? vs Jensen Healy, approx 2,200 lbs. with up-grades. Davd Vizzard-like formulas?  Thanks, roverman.

Hello again, About that hyd.lifter preload. If your using adjustable pushrods or adjustable rockers,(even better),Check  the threads per inch with a pitch gage or lay a known pitch thread along side of the adjuster thread. When they perfect match, thats your pitch. Now lets do the math, 20 pitch thread = 1000 div. by 20= .050" per rev. So you could put an index mark on push rod/rocker and a mark on adjuster. Adjust till free-play is gone, decide how much preload and turn the crude-but effective internal micrometer, based on known pitch to desired preload. In this example, 1 turn = .050" preload. If we're using Buick/Rover heads, the early Volvo 4 cyl. push rod motor has quite durable adj, rockers and shafts,(need to cut in middle and add press-fit spacer) This set-up is what Huffaker used in my GT-1 motor. Worked quite well up to 8,000 rpm with serious roller. Des Hamill's, Rover V8 book mentions OEM., steel, adjustable, replacement rockers. Haven't priced them yet. Power to the People, Art.

Art,

Thanks for the tip re adjusting the preload, it obviously a bit of a guess now that the engines built and don't particularly want to pull the manifold off to get into the lifter area so will be a bit of trial and error.

I'll try tightening the noisy lifter a couple of flats at a time and see what happems.

The adjustable steel rockers you mentioned are I believe the old Volvo ones originally used in the Group A spec race engines.

Kevin.

The Volvo rockers come from the 16b engine. They are very close to the stock dimensions but the shaft bushing is a bit bigger ID. It looked like 20 thou or so. Here's a pic for comparison:

volvoRockers.jpg

This one is missing the adj stud. I'm pretty sure it uses a ball with a cup on the rod if I remember right. The ratio is different too. 1.55:1

Just needs a bushing in it.

I don't suppose you know a part number or something? I'll post it on my website just in case it's useful to someone.

I don't know of an off the shelf bushing. A number of our gang (not me) would find that to be a very basic machining exercise.

Just got done degreeing my cam and the specs are a bit different from what I expected to see.I tried to check it as accurately as possible using an 18" wheel and a .050" sweep 1" dial indicator but found I was fighting 5* of backlash in the new double roller chain, compliments of the align bore (About a quarter inch of slack). I used a pair of solid lifters swapped in for checking. Anyway the actual specs are .424/.424 lift, intake open at 5* atdc (all at .050") closed at 52* abdc, exhaust open at 38* bbdc and closed at 7* atdc. Specs were .436/.436, -4btdc, 36*abdc, 40*bbdc and -8*atdc. The biggest discrepancies were closing of the intake (16* later than spec) and closing of exhaust (15* later than spec).

My measurement for lobe centers was 105 for exhaust measured at max lift vs 114 specified and I had a little trouble getting a good read on the intake, first measurement was 115 but it didn't take account of the chain slop. 2nd measurement was 121, vs. spec of 110. Lobe separation was specified at 112. I don't understand how you calculate the lobe separation angle so I wasn't able to come up with that measurement.

This is the first time I've used a degree wheel, could some of you more experienced individuals perhaps throw me a bone here and tell me what this all means? It sounds to me like the grind doesn't match the spec card and everything is lagging by almost 15 degrees except the opening points. As it stands I'm at a real loss as to whether the cam should be installed straight up or perhaps advanced some and if so how much.

This is a high compression (10.6:1) blower engine with low boost. We were shooting for economy and extended rpm range, not maximum power output. I suspect Charles may have extended the duration to enable the higher speed operation, but how much is that going to affect the economy?

Jim

MVC-286S.JPG

Did you mean to say -5º ATDC? If it's 5º ATDC that seems strange. the difference between 36º and 52º is insane. WOW.

I was going to say you could advance the cam a bit to balance the numbers.

Now that I look at it I really don't get -8º atdc for the exhaust opening from the adv. specs. And the intake opening at -4º btdc? This would equate to both valves being closed where there is overlap. Maybe it means -4º ATDC for intake opening and 8º ATDC for the exhaust. That would make more sense to me. Then again this is at 0.050" so maybe there is a tiny bit of adv overlap. Is this because it's for a superchager?

No typo Nick, at least not on my end. -4btdc would be 4atdc, off 1* from what I measured (5). The .050" measuring point does mean there is some overlap, but maybe not all that much. Charles *was* grinding it for a blower app. TA says in their catalog that all stock timing chain sets have 4* advance built in, which would (should) shift the numbers a little if I use the silent chain set. Maybe I can use the V6 chain tensioner with that. I'm looking into it. That assumes my double roller set is "straight up" and it may not be.

Jim

"TA says in their catalog that all stock timing chain sets have 4* advance built in"

That's so when it stretches breaking in, it will be closer to correct.  ;)

Maybe so. These numbers are at the stock location. Guess I'll run it like that and see, just need to get an oversize timing set, looks like probably .008" over. Anybody know of a good place to get that?

Jim