cam option

[hoffbug]

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..

[Dan Jones]

> 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

[NixVegaGT]

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.

[NixVegaGT]

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?

[hoffbug]

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!

[Mr. T]

Damn, I'm Iate for a party now!

[Fastag]

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

[castlesid]

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.

[castlesid]

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.

[ex-tyke]

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

[castlesid]

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.

[ex-tyke]

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

[castlesid]

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.

[Dan Jones]

> 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

[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

[castlesid]

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.

[NixVegaGT]

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. 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?

[BlownMGB-V8]

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

[Fastag]

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.

[castlesid]

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.

[BlownMGB-V8]

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

[castlesid]

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.

[BlownMGB-V8]

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

[castlesid]

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

[BlownMGB-V8]

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