Hello all,
Starting to plan out my 300 build, and have had a few public and private conversations with Jim B. that have been extremely valuable. Rather than continue to monopolize his time, I thought I'd ask some public questions.
Background: This is a '64 300 with aluminum heads and originally 2bbl intake, I have a 4bbl intake to use but not the 4V compression ratio. The engine is worn-out and needs complete overhaul, a lot of the internals are junk including the cam and quite possibly the front cover (oil pump) as the engine was on a run-to-fail program before the car was cashed-in. So assuming the block passes inspection, I'm a bit flexible on rotating assembly components. I consider dynamic balancing a must. Oiling system improvements, as have been well-documented, and explained to me carefully by Jim, also are a must. I'm installing it in a '78 B roadster with a V6 T5 and H-body bell. Rear axle has not yet been sourced but will likely be a D44 LSD between 3 and 3.4 RP.
I have been looking into the extra cost of components to use the late 350 crank, and I don't hate it.
I'm also confident in the ability of my local machinist, so I'd like to look into just the rotating assembly swap.
I've spent a lot of time searching, and can't find any breakdown on the evolution of the 350 crank, so I'm wondering what year spread and identifiers I should be looking for when shopping for a good 350 crank to use. Jim had mentioned the "late" version had enough counterweight to minimize the need for mallory metal when balancing, if the rods and pistons are light enough.
Improving the rod ratio to reduce side-loads, and ease of internal balancing when using the Nascar 6.2 take-off rods appeals greatly to me. Also the ability to dial in deck height by ordering a piston, as I'd like to set it so high-octane pump gas can still be used (I'd prefer something on the order of 9.7:1). I realize breathing improvements would be needed to maximize horsepower, but that's not my goal. I'd like to reduce stresses on the engine at the power levels I want to be using. I don't see the percentage in going so far as the TA heads for me, at least until I get used to the engine with stock ones (or perhaps slightly bigger valves), but I suppose it would be nice to have the bottom-end ready to take advantage if I did decide to upgrade later. But again, low to midrange rpm is 90% of where I'll be and I would like to drive the car quite often.
I hadn't thought of insisting on thoroughly vetting the block before starting machine work, Chris Gill's journal made that clear (while also providing a lot of inspiration and appreciation of his attention to detail!).
As an aside, a mild roller cam may increase my costs substantially at the beginning but the investment seems to be good economy to increase longevity of the valvetrain. I doubt many are asking how to make the most of a mild profile but if there's a resource someone can point me to, or if you think just a roller version of the stock profile is a good choice, I'd appreciate the feedback. Cheers.
David, I have a little experience with what you plan to do. The late crank has capscrew rods. 74-80. The roller cam that Jim B is doing would be perfect. Specs are GM LT1 "Hot" cam. You can go to 10.5 compression with the aluminum heads, The stock intake is not the best, but the only one available at this time. Brian Mcmillan is working with Anthony Laney in Australia on a great intake for the 300. I used larger 2.3 Ford sohc 1.74 intake and 1.5 exhaust valves in my 300 heads years ago. You will need larger valve seats. Chevy Z28 springs and Viton seals after guides were machined down and bronze liners installed. Are you going to use a carb or Fuel injection? I prefer Quick Fuel HR series or Holley Sniper. Any question you have I'll be glad to help.
Thank you Jim, and again, thanks for your generous help in past questions.
I've been following the Willpower Intake developments, but took up Glenn T on his generous offer of an original 4bbl aluminum intake. Indeed I prefer a carburetor for a number of reasons, so would prefer to go with that. Pump gas again is my preference. I've been reading input from both of you on the V8Buick sticky, but unfortunately do not have posting privileges there as yet. I do appreciate all the generous information being shared as it's clearly a niche engine with a lot of potential. Cheers.
David, 10.5 on an aluminum head is octane tolerant as 9.5 on an iron head. The cam Jim B is using is a hydraulic cam. Corvette 350 cam specs. He is using solid lifters with it. The Dynamic compression with that cam would allow premium pump gas.
Weak spot on the 300 heads are the rocker hold down holes. Steel thread inserts there are a good idea.
On the heads, you must pay attention to chamber volume as it affects your piston dish size. The 300 heads have about a 35cc dish which is quite large, the TA heads have about a 26cc dish which is much smaller. So the short block has to be built for the heads you will use. Now one rather clever dodge is to find a set of late Rover heads which are nearly as good as the aluminum 300 heads, build for those and the TA heads will then work as the stock Rover heads have the small chamber. That gives you the flexibility for a later upgrade without having to spend too much to do it. I'm using Wiseco slipper style pistons and got a good price on them, something like $1140 a set. You can have them reference mine if you like, they were sold to DAM in Culloden, WV. Shouldn't be hard to find. They are spec'd for the TA heads and a 10.5 CR and purchased within probably the last year and a half.
Cams: I actually have 2 roller cams coming in, one is a hydraulic grind and the other is for the solids. Both the same grind profile as Jim said though one engine will have a rather conventional redline and the other is built for extra speed capability, just because I want it. They are supposed to ship within about a week. Lead times have gone way up, figure on a couple of months or more. I bought those from TA and had them handle getting them ground also. Don't know if they have the cores back in stock yet though. We almost had to cut down a higher lift core and have it re-hardened. That is an option. Not many of these stock or near stock grinds get used for aftermarket roller cams, at least not yet. But we are in a rather specialized niche here as we have the luxury of an oversized engine and can build it mild and still get great performance, which makes for long life. And in street driving it's mostly about torque so a mild grind has some advantages until you start winding it up. The roller doesn't need oil squirters in the rods or extra zinc in the oil and one teardown for a wiped lobe pays for it. If you can get the Pankl rods they are extremely nice and offer more clearance for the block and cam but finding the bearing shells is a little tricky. Watch your crank end play, big end side clearance, and oil slinger clearance. Also rod clearance to the block at the oil suction galley casting and rod clearance to the rear cam lobes. Those will be close but with the Pankl rods should clear. Haven't checked the cam clearance yet but it should be OK.
Jim
Jim, One correction, 300 heads are around 55cc not 35cc. Typo?
Quote from: Jim Blackwoodwe have the luxury of an oversized engine and can build it mild and still get great performance, which makes for long life.
Yes, my thinking as well, thank you; though I have not built many engines (this will be my third engine specced in 25 years) and I'm a little rusty on how to get there. But this is my underlying motivation.
I'm assuming head gaskets aren't available in different thicknesses to give me some flexibility. But I'm certainly not opposed to committing to the stock aluminum heads if that's the case. Perhaps if I go conservative with my compression ratio and these heads fail at some point I can put in iron 300 heads later and build them, and deal with the handling issues of the extra weight if need be. Having run rear-drive cars that were heavily front-biased for most of my life and not having done any racing I don't anticipate this being a big problem for me, though I remember Anthony H. talking about the understeer of his 289 powered GT when I met him this fall, and without knowing how he drove it, I do get the value of neutral handling. The iron heads are cheap and at this point not yet too difficult to get, and that's always a hook for me. If I have to replace heads and can solve it with a couple hours on Kijiji and a few weeks at the machine shop - right on.
Quote from: Jim NicholsWeak spot on the 300 heads are the rocker hold down holes. Steel thread inserts there are a good idea.
Indeed, I saw those when pulling the shafts and remember how odd it seemed to have the bolts threading right into the aluminum if they're service removable and one was heavy coming all the way out so they need reinforcement for sure.
Question: Does anyone recall seeing a picture side-by-side of the late 350 crank next to an early one, or know the number for the late one (if it's cast into the crank somewhere)? I may have someone who can look for me but I can't rely on him to know exactly what to look for and knowing myself would make having him snap a picture for me a lot more practical. I think someone may have mentioned an extra counterweight on the flywheel flange but I have to admit I don't know what I'm looking at here. Locally I've located a '69 and a '71 that sold and neither had the rods to go with them, oddly no shortage of Olds 350s here but no late Buicks without the car yet, my friend is in the Edmonton area where there's a lot more supply. At least with 74-80 we now at least know where to look, so thanks again for that. Ironic that there's a gold nugget hidden in an undervalued malaise-era car and we can do something for little outlay that ought to cost much more, that's what's really tugging me to do this while I have everything apart and can take advantage. Cheers.
Thanks Jim, I do slip up occasionally, like anyone else.
For a mostly stock engine I do believe the late 350 rotating assembly could make a usable choice. The rod length is 6.387" which would make the ring package a tight fit. The deck on the 300 is .644" shorter than the 350 which means you have to find 5/8" between the lower ring and the top of the wrist pin and with the stock .939" diameter pin that's going to be really tight. But, the late capscrew rods are pretty good and fine for up to about a 6K redline, maybe a bit more. They should fit in the block fine and cam clearance will be exactly the same as in the 350. They use the stock bearing inserts and have oil squirter holes for cam lobe and cylinder lubrication. So as to the fit, with forged pistons the ring package can be moved up a bit especially if power adders aren't used. It's acceptable to go with thinner rings, and the rods can be bushed to allow the use of smaller diameter wrist pins, all of which should give more than enough room.
For example, in my 340 I used 7" rods with 3/4" pins and a fairly standard ring package on pistons designed for a blower engine. Distance between the pin and ring was not a lot, going from memory it seemed like around 3/16" at the most but let's run the numbers. A 7" rod vs 6.387" gives .613" so that leaves .031" to make up and there would have been room to do that. But, a 3/4" wrist pin while compact and light in weight, is not probably quite as durable as could be desired. A whole book could be written just about wrist pins but taking the piston manufacturer's recommendation is usually a safe approach. However, if bushing the stock rods is considered, a diameter in the low 8's should give adequate bushing wall thickness and this gives room with the same ring package I used on the 340. Hardened alloy thin wall wrist pins can give a weight of around 100 grams, less than half of stock. Now, this doesn't help much with the balancing as the stock rods are heavy so an internal balance might not be practical even with light pins and slipper style pistons, which shifts expenses from the internals to the flywheel etc, but it's still possible, and may be a good practical choice.
Jim
As to the iron heads, yes they do have bigger ports and valves and yes they are a bit heavier. Interestingly enough there isn't but a few lbs difference in weight between an iron head and a TA head. But the flow is considerably different. Weight difference between the stock alloy head and iron head 300 is 50 lbs divided between 2 heads and the intake just about evenly. So with the alloy intake it's only about 35lbs. and that much isn't going to kill the handling. Doesn't help but it can be pretty much tuned out. The late Rover heads are also a bit heavier than the 300 heads. So there are two very practical ways to go on the heads. Either the Rover with TA as an upgrade or the stock 300 alloy/iron combo. Either one works but the first has more power potential as you would expect.
Jim
On Chris's build the capscrew rods were lightened quite a bit by removing most of the balancing pads top and bottom. The 2.5 Sohc Ford Speed-Pro hyper pistons were a lot lighter and used modern thin rings. 1.19 compression height with small dish and valve reiefs gave about 10.2 compression. Those pistons standard size is 3.78 so .020 is 350, 3.8 standard size. Only clearance issue with the longer 350 rods was the shallow part of the oil pan need a little ball peen work and washers under the windage tray. Biggest expense was turning the crank down .5" on the mains. Also, the oiling hole has to be chamfered over to center and oil seal crosshatch polished for rubber seal. Ian, the owner of the car just told me it was running better than ever since he has had some Megasquirt tuning done. The iron heads have much bigger ports and valves than the 300 aluminum heads. You wouldn't notice the extra weight.
If you can look at the rods, the late cranks use the capscrew style rod bolts as opposed to the through-bolt and nut style so that makes an easy identifier.
Jim
"Full Throttle Enterprises" on eBay has a set of Pankl 6.2 Nascar take-offs for $85.00USD, so unless the bearings are extremely difficult to get or expensive I see no reason not to go with them (or say a slightly different height if we are playing with length to stay out of the ring pack/fine-tune deck height.
Very glad to hear the feedback about the iron heads. Certainly it seems worth it to me to find an extra set to play with.
I'll keep looking for a motor, that seems the only way to verify the rod type if I can't pick out the crank differences easily (which is good to know). No engines showing on car-part at the moment, but that usually doesn't include the u-pull sections so maybe that's not an issue. Cheers.
When you buy them get them to give you the order information for the shells and you should be good. Expect to spend more on the inserts than you do on the rods, maybe as much as 50% more and there may be only one size and one type available, the same one that is used in the racing engines. Which shouldn't be a problem assuming clean assembly of the engine. But the rods themselves are super nice. Wouldn't surprise me a bit if the MSRP is around 2 grand a set. I really like those rods.
Jim
Quote from: Jim Blackwoodthere may be only one size and one type available, the same one that is used in the racing engines.
Good point, I hadn't thought of that. Would the 6.2 Honda rods spoken about early in the v8buick sticky be a better option if I had some bottom-end problem and had to clean up the rod journals again? Or have they been looked at with the 350 crank in a 300 and maybe I just have to blaze a new trail. Cheers.
You won't know for sure until you ask. All I can tell you is that of the last 2 sets of rods I've bought one did and one didn't.. So the best thing is to ask.
Jim
It's possible I either poorly phrased my question, or "Honda rods" doesn't mean what I think it does. But I'm not proud, so I'll ask:
So when I hear there's only one size of service bearing (or there might be) for the Pankl rod (which would make sense on a stock car), I immediately think I have no recourse if I've sized my crank for it and have to clean it up later for any reason. So I think it might be better for me to use a production engine rod of the same length I want, like the 6.2 Honda rod, (does that reference the manufacturer, or just the big/small end dimensions on a race rod?) and if I spin a bearing on a rod I have some option to clean it up and throw it back together with a service undersize bearing. Of course, that assumes that a production Honda rod will still clear everything or be light enough to dynamically balance internally, which I'd prefer. Since I'm using a stick, I'd like to replace the flywheel without too much consequence if something should happen to the clutch. From how you've phrased your response I may have inadvertently stepped into another race rod of another size, which wouldn't solve this potential problem. Cheers.
David, I don't know any of the details about the stock Honda rod. Both the Pankl and Carillo rods I now have use a Japanese bearing size. I can't say for sure which one showed one insert available since Dustin chased down the bearings but I Think it was the Pankl. The rods had a serial number and he used that to match up the insert. Maybe you could use a different insert to match up for an undersized bearing, or resize the rod to do that, it seems likely to me but I have no way of telling you that for certain any more than I can say for certain that it was the Pankl rods or the Carillo. What I can say is that the Pankl rods were an easier fit in the block so I'd use them if I could. They also have that nice 3 dimensional mating surface where the cap mates, and it goes together like a finely machined watch. Between the seller and your shop I think the insert situation could be sorted out. Certainly can't beat the price. I've also used Scat rods and those needed one shoulder clearanced for the cam but they also used the Buick bearing shell. Of course the stock rods also work fine for more reasonable redlines but they are cast steel.
Jim
Thanks Jim for this, it appears I did mistake the "Honda" rod term to mean a production engine rod from a Honda rather than a race rod with Honda bearing dimensions. All clear now.
I think I have enough information to start tracking down parts. Cheers.
Chris's build is going on 8 years now! Another alternative is using 3800 Buick V6 supercharged pistons with the capscrew rods and 64 Aluminum or Iron heads. About 9.75 compression. Those pistons use bushed rod and smaller floating pins with circlip. 3.8 standard, so .050 over on the 300. Hyper with coated skirts and anodized crown. You would have to talk them into selling you two more piston and ring sets.
https://www.ebay.com/itm/304154551913?_trkparms=amclksrc%3DITM%26aid%3D111001%26algo%3DREC.SEED%26ao%3D1%26asc%3D20160908105057%26meid%3D3f9f90d7325545a3adbc2ae67fa84911%26pid%3D100675%26rk%3D1%26rkt%3D15%26sd%3D304154551913%26itm%3D304154551913%26pmt%3D0%26noa%3D1%26pg%3D2380057%26brand%3DEnginetech&_trksid=p2380057.c100675.m4236&_trkparms=pageci%3Aba264abb-797c-11ec-b982-66c74ef540b8%7Cparentrq%3A74995c0f17e0a9bd51769805fffdbee4%7Ciid%3A1
"300 heads are around 55cc not 35cc. Typo?"
I figured he just transposed the numbers. I always used the 53cc number. I have seen them listed as 53-55cc. I guess I need to measure mine.
I am leaning towards using my late Rover heads.
That would be a very viable approach Carl. I understand the aluminum used in the late Rover heads is also a bit more dense which is good and partly accounts for the weight increase. It makes the upgrade path to the TA heads an easy one though it is not inexpensive. My approach has been one of the cheapest and it includes $1600 for the bare heads, a couple hundred for used titanium valves, another $150 or so for beehive springs, same again for LS style roller rockers, and a fair bit of machining to make it all play nice. And then you get to the roller cam. Might manage to save a buck or two here or there but a completed set of heads for under 2K is tough (At the very least the seats need to be cut, and you can't run the OEM rocker assemblies). On the positive side the weight increase with the upgrade would be minimal, the CR wouldn't change, and it could be done at any time that was convenient.
But keep this in mind. While it is true that the greatest power gains in the SBB series of engines is to be had from the heads, the power output of the stock 300 in any trim level is more than adequate for the car. It was only with the latest Rover heads that there was anything OEM from England that approached the stock alloy 300 heads and the iron heads were better. Combine that with the displacement advantage and you would be right in expecting the 300 to make more power. Combine that with another 46 cubic inches from a 350 crank and standard overbore and the torque goes up, the hp goes up, and general usability and flexibility goes up. My guess is that at some point Dan Jones might have compared the irons on a flow bench and that info would be useful. BTW, these are the same heads that the factory used on the 340, so while their flow won't match an unported TA head it would be very wrong to think of them as inadequate.
Jim
I found this link while searching for a machine shop....nice visuals on some of the oiling mods for the Buick, assuming the 350 & 300 have the same oiling setup.
https://streettechmag.com/2015/08/04/buick-350-engine-build/
Hey Brian,
Thanks for adding that, it's the article I referenced earlier and to my understanding is very similar to what's required on the 300 with perhaps some dimensional adjustments.
I have not seen much discussion lately about applying GE Glyptal to the block interior surfaces (in my own searches) but did hear about that long ago being done in heavy duty industrial engines and will be adding that to the build. The local alternative product I have is Dolph-spray ER44 but it is for the same application. For the cost of the product I think it's worth looking into especially if we are trimming/blending casting flash as well. Cheers.
I don't agree with several things they did on that engine but most particularly the use of the long gears in the oil pump. They have been shown to cause wear in the drive gears and if the rest of the engine is built properly are completely unnecessary.
But of course from all indications they were building a race engine and that changes some things.
Jim
QuoteThe late Rover heads are also a bit heavier than the 300 heads.
I was curious about this, not that a pound or two is gonna sway a decision. So, I went out to the garage & weighed three heads. Scale used was my Soehnle German digital bath scale.
Buick 300 18.8 lbs
Early Rover 3.9 20.1 lbs
Late Rover 20.8 lbs
All heads weighed with valves & springs, but no rocker shaft assemblies.
Jim... "I don't agree with several things they did on that engine but most particularly the use of the long gears in the oil pump. They have been shown to cause wear in the drive gears and if the rest of the engine is built properly are completely unnecessary".
Jim, concur. Believe this article may be a bit dated but I like the pics of the different oiling mod drill portions. If there's something else you're not agreeing with please share.
My intent if I use the 300 is a mild build of the block with all new components. I don't need a stroker engine as anything north of 250hp is more than enough and I believe I can get there with an updated cam and flowed 300 heads with the larger intake/ exhaust valves.
I have most of the parts needed (minus internals) to move forward with the 300 build, once I know the status of the intake manifold build (Willpower) and how much massaging the transmission tunnel will be needed (67 GT) I'll make a decision. I also have a nice Rover 4.6 if the 300 becomes too much of an issue.
Thanks for doing that Carl. The Rover block is also a bit heavier than the 215. I think the 300 heads are the same weight as 215 heads but not certain.
Brian, I did not read the article thoroughly so I'm hesitant to criticize and as you say it is dated. Much of what is in there is useful but not necessary, such as enlarging the delivery side of the oiling system. If it isn't gushing out at the bearings it doesn't take so much volume. I also think there is something to be gained by increasing the suction galley past 1/2" as evidenced by Buick going to a 5/8" pickup but a piloted drill is needed to do that safely, I use 9/16" and it seems to work quite well. You can go bigger but you risk a breakout. If that does happen it is repairable with hardware store brass tubing. but best avoided. I find radiusing the corners in the suction side and porting the pump and stabilizer plate to be helpful but the main thing is to keep those clearances tight.
For a max build some of those other things could help. I've been known to drill from the mains to the cam 3 o'clock position for example but I'm not at all sure that made any difference. Another thing that you used to see was an external line to the rear of the oil pressure galley. But again, that was back when they were trying to run SBC clearances. Sometimes you might see an oiler for the cam/distributor gears and once in a great while you might run across piston squirters. But a 250 hp build is very nearly stock and you can quite possibly get there with the right combination of carb and exhaust on a stock engine. You are already at 210. If you do no more than increase the valve spring pressure so that you can get up to the 5500-6000 range you should be there. We are limited on the headers of course so that can't help very much. A small bump in the cam will do it though. 100-120lbs of seated pressure should get you there. Porting is generally either expensive, or risky and labor intensive and primarily suited to when you have to have that little extra boost to get past that one guy on Saturday nights. Bigger valves don't hurt if you are replacing them anyway but lots of times you don't have to. I'd use the cam and not get overly enthusiastic with it. The bone stock 300 is admirably well suited to the MGB so the performance is quite pleasing without it, and as Chuck is discovering with his stock SBC, has the advantages of low speed torque which makes driving it a rare pleasure. That's that 310 ft/lbs of torque working for you. So my suggestions would be either shim or replace the valve springs, give a small bump to the cam, and see how you like it.
Jim
Jim, great info/feedback as usual. thanks for taking the time.
Current thought for setup is the 64 300 block and heads with larger valves and stiffer springs. Undecided on the rocker & lifters setup whether to retain stock (new steel inserts for heads) or go with something off the shelf. Cam is a Crower 230 or 232. I've got the original intake and a Willpower being cast for the 300 setup. The Willpower will more than likely rob some low end torgue but thinking there's enough to spare and and with the FitTech TB setup I may recoup some torgue. I'm thinking to dyno with both intakes just for comparisons sake. I have a stock 300 flywheel that I'm gonna see if I can get machined down to 24lbs. The rear gears are GM 7.5 3.42 gears with torsten posi and disks. The tranning is a new GM T5 V8 with the .73 5th gear.
Jim N is local to me and a wealth of info so I just keep picking his brain. Eventually I'll get up his way to visit.
The main difficulty with the stock flywheel is the balance cavity which is on the back. If the flywheel is lathe turned to reduce the weight it means that some means must be used to restore the proper balance if the mass is cut from the back as the size of the cavity will be reduced. I have lightened one to about that weight by turning the face, but then had to use countersunk capscrews to have room for the clutch hub, an approach I'm not sure I would recommend. It is possible to bolt on a weight opposite the cavity on the back side to restore the balance. If the engine is to be balanced during rebuild this is a bit less of an issue.
Jim
Is there someone I can contact at the V8Buick site about getting my account approved as a full member? I did send Jim at Trishield an email, but that was almost a month ago.
I'm not as anxious about posting as being unable to view the photos, I can only see thumbnails which means I'm missing out on some good visual aids posted over the years.
Usually that is automatic once you've made the minimum number of posts. Something like 5 or 10 I think?
Jim
Hi Jim, thanks and sorry for the late reply. I did join but at the moment I neither have posting privileges nor access to image macros. Jim Wiese posted in the News section that as of last August 15th all new registrants have to be manually approved by him. Cheers.
Can you send him an IM?
Jim, unfortunately that isn't an option either until I'm approved but if you know of another member who has his ear I'd happily send an email to them. It doesn't look like joining the site adds any functionality at all until the manual approval is done and I have reached out to him via email.
David, What is your user name for the V8Buick site? I'll try to PM Jim.
Same boat here.....joined over a week ago and have had no response other than I need to wait for approval. Unusually slow for an online forum.
Brian, I'll mention you too. What is your user name?
My username is the same as it is here Jim. Thanks for looking into this.
In the announcement thread where Jim states this new policy moderator Brett Slater asks Jim to check his conversations, and that was on Jan. 1st, so I wonder if Jim is OK.
Probably just busy. He is a respected engine builder.
Jim
Jim Weise says David and Brian are good to go on V8Buick.
Hello everyone,
I'm new here and planning my engine build (for a MGB-GT Sebring project). I have a Buick 300-4 (aluminum heads and 4 BBL intake). Was planning a non-stroker with the original crankshaft and the following:
- Intake manifold ported and converted using Doc's dual plane approach
- Holley 650 4 bbl carb
- Original cast iron exhaust manifolds ported, polished and ceramic coated (inside and out)
- 502032 Crower "performance" cam
- .030 cylinder overbore
- Nascar 6.320 connecting rods with Ford Turbo 2.3 flat top pistons—estimated 10.3 compression ratio
Before I commit to this approach, I wonder if anyone has any idea the approximate power difference between my plan and a stroker build using the Buick 350 crankshaft? I realize I'd need to change the pistons (currently looking at some Chrysler V6 flat top pistons with a lower compression height, which I'll have to hone slightly for the Ford wrist pins)—the goal is a similar 10.3 compression or so.
Also, IF I were to acquire a 350 crank, I see most of them are reground—will that cause any issues with rod bearings for my Nascar rods (which are supposedly 2.0" with bearings)? Any other issues with a stroker build that makes it a lot harder than keeping the original crank and lower CID?
Thanks everyone.
Eric, Maybe 50HP and 50TQ depending on cam. I'd go up one on the cam. The stock exhaust manifolds won't fit. There are some Rover ones that may but you will have to use a different ujoint on the steering, You can get undersize bearings the same as the rod journals on the crank. What piston are you thinking about trying?
Rover exhaust manifolds:
download8.jpg
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Thanks Jim! Your insight is really appreciated. 50 is definitely a number that makes this worth considering. I guessed I should have also asked what the total HP/TQ numbers might also be, as I want to make sure I'm not going to destroy my transmission (a Tremec 3650--supposedly a lot stronger than a WC T5, but still has its limits). Good to know on the exhaust manifolds, too. The pistons I'm looking at are Chrysler/Dodge minivan 3.8 V6 flat top (3.78 bore and 1.283 compression height). I haven't spent too much time looking at whether the pistons or block deck might need a bit of milling, but it seems to be close (and I'm sure the choice of head gasket will affect the quench number, too). The piston pin hole is a bit smaller than the Ford size (.901 vs .912), but I was thinking that I could use Ford pins and have the piston holes honed to fit.
Chrysler3.8V6Piston.jpg
Jim, in your opinion, which of those two Rover manifolds would flow better? And are the shiny ones aluminum? That might be nice, too.
Sounds like a plan. I try to build one HP per cubic inch for a strong street motor . 350HP and about 400 TQ if done right. Your transmission will be fine, What length are your rods again? Shiny ones are probably Jet Hot coated. They are also Tri Y design. Two pipes go down from them to a Y on each side. The top one is more conventional,
TS import big bore RV8 headers:
MGBV8_header2.jpg
I ran those pistons on the calculator and they are .020 below deck and 10.8 . If you remove the lug in the chamber you would be 10.5. Looks good.
Jim, thanks for running those numbers. I am not an expert on engine design, obviously. I have done some reading and I read that ideal "quench" clearance seems to be .040" With the pistons .020" below the deck and a composite head gasket, will that give me this optimal quench? Of course, also removing the lug you mentioned.
Quench doesn't factor with open chambers like the 300 heads, If you used the later Rover with 29cc chamber or the TA heads I would try to get Quench. Small wedge chambers need Quench. Open chamber and Hemi's do not. With high compression small chamber heads with Quench are less detonation prone. If you want a little lower compression unshroud the valves on the outside and clean up around the spark plug hole. Probably get it down to 10.2. 10.5 with aluminum heads is about the same as 9.5 with iron as for detonation. You can retard your cam 4 degrees and lower your Dynamic compression. I would still run pump premium.
Interesting discussion on open chamber vs closed chamber and Quench:
https://www.tapatalk.com/groups/clevelands/open-vs-quench-george-dan-jones-t17441.html?
Jim,
Learn something new every day--I had no idea that quench related to the shape of the combustion chamber. Thanks for setting me straight.
It seems like I need to keep my eyes open for a good late (?) 350 crank. Do you have an opinion on whether these cranks need heat treating after the mains are ground so much?
Eric I added a little to the thread above. Not heat treated but I would polish the journals. The oiling holes move a little and need to be moved over to center, I would take the 300 crank to the machineshop so they can compare.
Again, great advice. Thanks. Sounds like with my aluminum heads, I could run 10.5 assuming I ran pump premium (which I plan to do, anyway. I could even run Sunoco 93, if necessary). But perhaps, unshrouding the valves and cleaning up around the spark plugs is not a bad idea, anyway.
In addition to turning down the mains 1/2" you will need to thin down the oil slinger to fit the 300 block. The rear seal journal should be ground just enough to remove the hash marks if using neoprene seals.
Jim
Thanks Jim,
Is there a list anywhere of all the things needed to do the 350 stroker properly?
Other than the crank mods and different stroke everything is the same as the 300. V6 3 keyway roller timing set and front seal. Best Gasket co make a specific 300 neoprene rear seal. I have heard the V6 rear seal works but haven't tried it. 350 HEI distributor works. There is an MSD offshore clone distributor on Ebay that Clinton used on his 300 build. Search on the MGexperience Swaps board for a lot of Chris's stroker info and Clifton's 300 build. V8Buick board too. Jim B and I are on all these boards with info.
This chart is helpful, rod bearing clearance is wrong though. Should be .0007-.0015 same as mains:
https://www.teambuick.com/reference/300-340_engine_specs.php
Great, thanks!
Hey JN,
Thanks very much for helping chase down my manual approval on v8buick, it's very much appreciated.
I'm very motivated to use cast exhaust manifolds on my build, do you have any input on whether the 1st set of Rover manifolds fit better on an MGB, and where to find them? My understanding is the second set pictured is for the GTV8 and are quite rare.
I can't see my stock 300 manifolds fitting unless I flipped them upside down and backwards, and fair-play I guess but it's not the look I'm going for. Cheers.
Not that difficult to get 300 RWHP from the 300 & forget all the time, money, & headaches with the stroker build.
David, You're welcome. I have no idea on the Rover exhaust fitment . They look like you would have a better chance with them. Still would require fender massaging and that pesky steering shaft may be an issue.
Carl, yeah, it's a conundrum. Either way, it's a very fast car. Really fast or scary.
"Not that difficult to get 300 RWHP from the 300 & forget all the time, money, & headaches with the stroker build."
Amen to that......sporty 300 build in these cars should work well.
Thanks Jim, I was also was approved on the BuickV8 site.
I can tell you from experience that a totally stock iron head 2bbl 300 fitted with a 4bbl intake in the MGB will do just fine.
Jim
Not to challenge that point of view as I don't have a sentimental attachment to the idea, but can we talk about that for a minute?
Is the idea of using the 350 crank to improve rod ratio, reduce thrust and overall stress at the power level I want really not worth the bother?
By my read, while the engine is apart for a regular overhaul, we are looking at the following:
-find a viable 74-80 core and pay the labour to turn down the journals
-secure a suitable set of rods with the length and clearance we need
-order a set of custom pistons in the dimensions needed (one of the big ticket items at $1000+)
This is what's being added considering the existing crank will require regrinding, speedi-sleeve and new pistons, rod resizing and dynamic balance of the rotating assembly.
Since the cam is roached we need to replace it anyway, and the extra work of
-ordering a custom ground cam meant for roller followers (the other big ticket item at about $1000 so split the difference with a stock/reground flat cam, where do we land here: about $6-700?)
-a set of roller followers to reduce wear and the need for oil additives
by my read will pay for itself the first time we would need to replace a flat-tappet cam, as Jim B. already pointed out.
With the goal of not increasing power output as it's not needed, but reducing wear and improving reliability with likely some low-end torque gains, are we saying this isn't a worthwhile exercise? If we are, that's a welcome perspective and feel free to elaborate, I won't be offended. What's fueling my enthusiasm for the idea most is the notion we can take a stock crank of little value from another engine and for relatively little money, solve the crankshaft part of the stroker build equation. Seems like a valuable gimme. Cheers.
Hi David, I like your thought process. IF I'm correct, I picked up the necessary rods for $100. And the pistons are about $150 (plus the labor to hone the pin holes a bit--I'd probably pay to have the pins fitted anyway). So, I *think* my cost is the 350 crank and grinding the mains--and if I buy a reconditioned crank, I don't have to pay for the rod journals to be ground (not that that's equal),
You have a strong grasp of the situation. My TA cams that just came in cost me $850 ea. but if the low lift blanks had been in stock might have cost a bit less, say around $750 perhaps. What you need for rockers depends on the heads you use. With stock heads you can use stock rockers. The Wiseco pistons were about $1150. Cost of the rods were on par with reconditioning.
The crank can be an expense. In my case I have a lathe and was able to cut down the mains myself but it took time. So if you figure $500 for that you are looking at about $2500 extra to do the stroker and roller cam setup with forged rods and pistons. Not bad for what you get, and probably worth it even without the extra stroke, pushing the potential redline up as far as you like below about 7500rpm. If power is your goal, add TA heads, a porting job, and that new intake and then about all you need is a good set of equal length headers which you'd have to make yourself. By that point, depending on cam specs you could be well over 700hp.
But let's be reasonable. Anything over 300 hp is plenty in the MGB and you don't need all that to get there. So with the exception of bragging rights, grudge races, and just being able to run with the hot shoes (which it doesn't take power to do, just ask Carl), you can get there cheaply. OTOH, say you stay stock or near stock with the stroker/roller combo. Now your oil change intervals just went to modern standards, perhaps as much as 15K+ miles, a 5 fold improvement and with cheaper but better oil. No more worries about flattening cam lobes. Your torque curve just got wider, flatter and higher so driveability improved considerably, and your overall power level went up. All this while remaining understressed for great durability, which these engines were renowned for in the first place. Mileage might improve as well. Add efi and you now have a thoroughly modern engine and very likely the last one the car ever needs. Does that make it worth it? Some would say yes and some would say no. Dealer's Choice.
Jim
Can't talk about pistons without considering the heads. Our choices are:
-Stock alloy heads 57cc
-Stock iron heads 57cc
-Late Rover heads (4.6L etc) 29cc
-TA heads 31cc
As is clear they fall into two categories based on chamber volume so the pistons need to be selected with the correct head in mind. Likewise the heads need to be selected with the future in mind. For instance, if you can foresee ultimately ponying up the big bucks to get the best heads but want to do that later, the Rover heads would be a good choice. I don't have the valve sizes but maybe someone can post them here. The iron heads do have larger valves and ports and probably the most flow of the stock heads, followed by the 300 alloy heads and the 4.6 heads close behind. Weight difference from a single iron head to a 300 alloy head is 17lbs. The rover head is a couple pounds heavier than the 300 head and the TA head is about 10lbs heavier. so the economy performance build would favor the iron head despite the weight disadvantage. Bearing in mind of course that the stock iron intake adds an equal weight penalty. To put this into perspective, the 300 with alloy heads and intake comes in at 50lbs more than the 1800. With Iron heads this increases to 85lbs. In terms of front/rear balance, use of a D44 or 8.8 axle balances this out pretty well and any remaining concerns can be dealt with via swaybar sizes and tire pressures.
The small chamber heads can benefit from pistons which provide a squish area whereas the larger chamber heads, not so much as there is only a very small area that would allow this. Using a conventional .040" thick head gasket, about 65cc of total volume excluding the squish height works out to around a 10.5 CR in the stroker engine. That would be at zero deck.
Jim
Great discussion, information, and perspectives. I had a beautiful 1980 with a mildly modified original engine. It was really no fun--just felt crude, ran hot, and was unreliable. I'm looking for a vehicle that will be reliable, because without that, it'll sit there most of the time and never get used.
1980_MG_MGB_Carmine_Red_Eric_Cumming_000.jpg
I have read on another forum that the answer is always..........................Miata. :D
Hahaha, Yes, with a Ford V8.
No way. They started using Chevy LS engines years ago. :)
I'm on the lookout for a 350 crank, if anyone knows of one. I have found a few reman cranks, but not too sure if I want to go that route as I'm concerned about whether they may have the rod journals reground significantly. I see mention of preferring the "late" cranks if you're using heavier rods (as I likely am)--can anyone confirm the year range for that version? Thanks much.
I think 73 mid year so I would look for 74-80.
Another reason to use the ex-nascar rods: You grind the rod journals to the new bearing size, so all journals are at standard size and bearing clearance can be tightly controlled.
Jim
Thanks to both of you. I've been looking for 75 on but didn't know if I could go any earlier. BTW, my Nascar rods have a 2.0" big end, so trying to keep as close to that as possible. I've heard some of the reman cranks go several sizes over, so I'd like to find a late one that has never been ground, if at all possible.
I found someone with an early ('68) 350 crank. I know these are not ideal as the balance is lighter. Is it hard to make them work? Do you have to add weight to the crank or, perhaps, just the flywheel? I am hopefully going to use 6.320" Nascar rods. By the way, I am probably going to go with one of the billet flywheels, by the way, since finding an original wheel is probably next to impossible.
You will have to add Mallory metal to balance. I'd just get a reman later crank and after the mains are cut down and other machining have the crank nitrided. That will add about .005 to the journals. You have to polish the journals. You can get undersized bearings for the rod journals. You can get a 168 tooth SBChevy V8 flywheel cut down the same as the stock flexplate and use a 225 V6 Jeep ring gear. One bolt hole needs to be slotted and the flywheel is neutral balance so you have to add a bolt on weight or internal balance the motor and damper.
Mallory metal should only be needed if you are going for an internal balance. Otherwise metal will have to be removed unless you use stock rods and heavy pistons. For internal balance a combination of the late crank and the lightest rods and pistons may avoid the need for mallory metal or may not. With an early 350 crank, about 600 grams of rod and about the same for pistons, a pair of 1" mallory slugs were needed. That setup uses the modified SBC flywheel and a zero balance damper.
Jim
Thanks again to both of you for the advice--you're a wealth of knowledge.
Jim B.: Are you saying that IF I use an early crank and don't go for internal balance, I'll need to remove some weight from the crankshaft? "Otherwise metal will have to be removed unless you use stock rods and heavy pistons". My rods are about 680 grams and I assume the pistons will be lighter than stock. Just want to make sure I understand what you're saying.
Eric, Your rod weight is close to the stock later 350 rods. The early crank is lighter. The pistons will be lighter. They may add a little weight to crank or flywheel and damper. Chris used the later crank and rods with much lighter pistons and added no weight but crank was drilled and lightened. He did internal balancing though.
The heavier rods offset the lighter pistons somewhat so you may be close. If those rods are the same width as stock SBC rods they have .050 milled off each side of the big end and use early small journal SBC rod bearings.
There's a formula, half the rod weight is rotating and half is reciprocating but without getting into that, lighter rods and pistons mean less is needed in the crankshaft bobweights. With light rods and pistons considerable weight has to be drilled out of the stock early crank with external balance and even more with the late crank. This is why it's feasible to internally balance the assy provided the rods and pistons are light enough. (~100g. can also be lost at the wrist pins.)
This internal balance allows the use of less expensive SBC flywheels and a variety of dampers including aftermarket fluid dampers. However, as Jim mentioned one hole has to be elongated for the flywheels to bolt up, and it can affect the stack up on the throwout bearing, so those areas need attention.
OTOH, external balance leaves the damper and flywheel stock which means all parts can come from Buick sources. Also an advantage.
I'm building one engine each way. Both are equally valid approaches. I'd suggest you ask your engine balancer for his recommendations given the parts you have in hand.
Jim
Great advice, thanks. Nice that I can go either way. Hadn't thought about using a SBC flywheel, but that gives me more to think about.
My question about using a 340/350 stroke ? Lightweight LBC actually need that kind of torque ?
Art.
Yep.
Jim
No more so than does a Ford 347 stroker. Probably not to both.
Hey Art,
It's a fair question to ask. Even the best of us need a good technical devil's advocate to pull us up when our perspective gets out of hand and I'm no different.
I had considered doing this only because:
-I was dealing with a core requiring a full overhaul and the additional cost to do this work with a viable late 350 crank was much less than it would normally be;
-I was looking strictly at improving the rod ratio to reduce thrust wear and improve the service life and efficiency of the engine while flattening the torque curve rather than a max effort build with the most torque possible.
Now that I have a good running marine engine it no longer makes sense to undertake, and I imagine I'll be happy with the engine more or less the way it is, but I'll still hang on to my core and pursue this on that engine for some rainy day years from now IF I get tired of the engine I have. I'm not too proud to course-correct if it gets the project finished sooner. I feel like the first rule of filmmaking should be the first rule of hot-rodding: FINISH THE HOTROD. So many great ideas don't get finished and Coppola was a great filmmaker but this car isn't the hill I want to die on. I wouldn't advise someone to take this work on unless the rotating assembly already needs attention - but as Jim B. stated, there's a lot more versatility to an internally balanced engine if you're looking at modifications that aren't compatible with the stock vibration damper and flywheel and that can save money and time that pays for it. One can only answer this question meaningfully if we look at all the goals of the builder and the car they're building.
One could argue the stock 18G/V engine alone is enough for this car - I'm going to be brutally honest when I say I never gave the MGB a second look until I realised you could stuff a V8 into it with no major metalwork. Now I feel like I won the lottery. I don't think any AC Cobra or Sunbeam Tiger owner is complaining about the extra torque, but I'll never afford one so I'll build this one and find out for myself, I guess... It sure looks like fun to me! And let's not forget that a RBB is a malaise era car and isn't getting on the lawn at Pebble Beach anytime soon so if it's a bit overpowered, a bit disorganized, panel fit is off, you're really not going to gain much by obsessing over getting it perfect unless it makes YOU happy. One man's opinion.
Cheers.
If it's torque you are talking about, many of us have by now driven the MGB-Roadmaster and the unanimous consensus is that it's an easy car to drive.
Jim
Should you look on the Stan Weiss, flow reports, website. Much is revealed about the 300 alum. vs 300/340 iron head flow
capacities. Iron head int. dia. was increased by reducing exh. to 1.37". Ported it flows 104-130 cfm., partly because it's
.76 diameter of intake.
Onward, Art.
This?
http://www.users.interport.net/s/r/srweiss/tablehdc.htm#Buick
I think most of us know that the Buick 300 aluminum head doesn't flow as well as the iron 300/340 head.
My late Rover 4.9/4.6 head flows as well as my Buick 300 head.
Yes, the marine engine comes with iron heads so that problem is solved, but thanks very much for mentioning Stan Weiss (I had to look him up before Carl posted the link) and the data is fun to run through. As I said I was looking at the stroker for different reasons that the head won't solve, but it's a fair point.