I recently purchased a '72 in fair condition. Doesn't need too much body work, frame is straight and relatively rust free. It's currently a column shift auto but will be converted to a floor shift 4-speed, non-console with buckets. I have a nearly new over the counter Super T-10 that GM dealers sold with a nodular iron case and high nickel gears. It's in perfect condition. I also plan to use a Hays billet flywheel and C/F dual friction clutch. I already own a F#*& 9" rear end with nodular center section and posi carrier, so having it cut down and set up for the Chevelle is much cheaper than locating and reworking a 12-bolt. My dilema is this: I have a Dart Big M block that's fresh honed at 4.600 and a set of pistons that will work with either application. I don't own the rods yet, but can buy new of whatever length I need for a reasonable price. Heads are Pro Topline 320cc runner pieces that have been angle milled to 103cc chambers. I have a 3.766 stroke nitrided 427 crank and a new 5140 GM 4.0 stroke crank. Both are new in the box, never run. The 427 crank makes 500 inches and the 454 makes 532. Static compression ratios work out to 9.9:1 and 10.4:1 respectively with these heads. This car will be a street cruiser with very few trips to the strip. The tranny is rated (by all the experienced folks I've talked to) at around 600 ft/lbs of torque. I want driveability and don't care to scatter tranny parts all over the street. I want to go roller, either solid or hydraulic. I'll be putting a hydro-boost brake unit in and removing the A/C, so valve adjustment shouldn't be extremely tough. My gut tells me to build the short stroke/big bore engine for a bit lower bottom end torque (safer for tranny, better traction), but the "more power, Scotty" bug says go for the 532. I'm sure that the short stroke engine will still have plenty of power to spin the tires at will, but I've been guilty before of putting one together and then wanting more power after a while. I'm definitely not planning any high rev launches or power shifting. One other thing I'm considering is intake - single plane or dual? I think that for streetability, the big ports and single plane intake will knock off a good bit of the bottom end which should be good for traction, but will it be too much? I've read multiple posts from folks with 502's and they all say that there's much more power there than is needed and the short stroke engine should make close to that much power, just with higher rpm's. This combo was originally destined for a Corvette, but there was no way to get that IRS strong enough on my budget. I'd appreciate any thoughts, comments or suggestions you could provide, including rear suspension ideas. Since I haven't had the rear end fabbed yet, I can do pretty much anything I want with regards to perches and mounting points. Thanks in advance for your help and suggestions.

i dont know **** man but your post is a PAIN to read... tongue.gif

You don't need a roller cam, imho..

D2K say's my mild, about 9.8 to 1 oval port headed 496 with a 750 and a Strip Dom. and 1.75" headers should put out 550hp at 5500rpm and 580t at 4500rpm so to me is good streetable power..

But to each his own..

pdq67

Sorry this is so wordy, but it's a complicated decision. pdq67, thanks for the reply. I have both sets of rollers in my hands, so all I'd need is a cam. After all the break-in failures I've seen, I think the safe play is roller, particularly since we're talking lift of .650 or less. I'm curious as to how the torque curves work out on the short 3.766 stroke 500 vs the 4.00 stroke 502 versus the 4.25 stroke 502. There's .290 difference in bore and .500 difference in stroke from the short stroke/big bore to the big stroke/small bore combos.

Those iron case Super T-10s are only rated at about 325 ft.lb. of torque safe, so either motor is way to much for your tranny. Only the high dollar manual transmissions will be safe if you stick it to the ground hard. Street tires should keep it from breaking but it won't run extremely quick E.T.s with them. The newer TKOs are the only street sticks rated at 600 ft.lbs. Several racing manuals can take the torque you have without breaking and the extra cubic inches will make more usable power. The super T-10 will probably have the lifespan of an ant at a picnic if you put slicks on the car. If the crankshafts have crossdrilled mains don't use them either. This item is addressed on the Reher-Morrison website in a tech article.

Tex Racing Transmissions and S/K Speed both told me that the tranny is good for 600 ft. lbs. This is not the factory installed tranny which is what I think you're referring to, it was sold as an over the counter only transmission. The case is not grey iron as were the early Super T-10's, it's nodular and the gears are high nickel. Thanks for the heads-up on the cranks. I'll check 'em both. As I understand it, high revs is where they cause problems. This build-up question has everything to do with what the tranny can handle - will the shorter stroke kill enough on the bottom end for it to get the car moving before I really hammer it since that tends to be where manual trannys get shelled rather than at higher speeds. Thanks for the replies.

The strength of the transmission is laid out in one of my Mustang magazines but it will take some time to find it. If the slack is taken out of the gears by shimming back the main drive you can make it live a lot longer. You can feel how much slack is present by rotating the input back and forth by hand and seeing how much play is present. It sounds like you have a knowledgable transmission man close by. The nickel gears should make it stronger but i've read that the distance between the input and cluster shafts are the main determining factors in the boxes strength. You might also check with Liberty.

Thanks for the advice - that's a lot of what I've heard. Don't go to any trouble, but if you happen across the magazine, I'd be curious as to what it said.

For an approximation on torque differences I ran this through D2K for grins.

I used a CC 288 street solid roller, (288, 110/106, .600" lift net), and the smallest rect. heads, small open headers and a single plane with an 850 carb. as a baseline for both.. Just changed the stroke and CR. from 9.9 to 10.4 and 3.76" to 4" when I ran the bigger motor is all..

RPM-------Small Motor--Big motor
2000------524----------574
2500------554----------605
3000------582----------632
3500------617----------664
4000------641----------683
4500------653----------688
5000------646----------673
5500------624----------641
6000------582----------587
6500------528----------525
7000------466----------456
7500------402----------385

Please look at JUST the trend and not the combinatrions b/c I bet they both can be tweeked separately to make quite a bit more power anyway..

Hope you can get some guidance outta this..

pdq67

Thanks! That's exactly what I expected. What happens now when you roll it to a 4.25" stroke with a 4.320 bore (should be around 500ci, right?)?

498.4".. (Just .010" bigger bore then a 496 is all)..

pdq67

PS., I've dreamed about onna these on the Boards many times..

A 4.625" b x 4.375" s = 588" motor using a standard deck height block for the ultimate 396" stealth motor..

He, He!!

What's the torque curve on one of those 498's? By the way, I have a line on a Cola 4.375 that lost a bearing on it's first dyno run, fresh turn at .010/.010 for $750 if you happen to know of anyone who wants or needs it. The only problem with that stroke is availability of pistons and rods. Massive torque, though!

498.4" motor and not know it's CR, I used 10 to 1.

RPM-----Torque
2000----525
2500----554
3000----580
3500----614
4000----637
4500----647
5000----639
5500----615
6000----571
6500----516
7000----451
7500----386

pdq67

Thanks again! I plotted all 3 on Excel. Big bore with 4.0" stroke is up all across the curve, as expected, and all 3 nosedive at about the same point. Very interesting, though, that the 498 big stroke/small bore engine has a torque curve that almost mirrors the short stroke/big bore engine. My bet is that a 502 with 10:1 or so would do almost the same thing. Does the big bore really give enough additional piston surface for the expanding gasses to work on to make it mirror the long stroke engine or is that a fault of D/D?

Get yourself a copy of Ed Staffel's great book called, "How to Build Max Performance Chevy Rat Motors" by CARTECH, (ISBN 1-884089-20-8) from say Barnes and Noble or Amazon..

B/c on page 51 it has a chart of five, 4.50" bore, BB motors that are all the same EXCEPT stroke is changed from 3.76", then 4.00", then 4.125", then 4.25" and finally 4.5"..

It is a very interesting chart b/c hp stayed pretty much the same AND at pretty much the same rpm level for all motors BUT torque increased b/c of stroke increase!!

Interesting to say the least b/c you can't change bore and stroke AND not change the other components like head size, intake size and finally headers size, etc.. Otherwise a motor as you stroke it doesn't max. out and therefore leaves power on the table..

It will however still make more power due to no more then it being bigger then it was..

pdq67

I have the book - acutally loaned out to my neighbor. One other thing he has in that or one of his other books is a chart that shows piston speed at different stroke and rpm combinations. I'd actually forgotten about that - I'll have to get it back so I can study it more. Thanks for jogging my memory.

Don't mean to wonder too far off topic, but I was wondering if anyone here has gone from a 454 to a 496 and what kind of E.T. increase the car had. I'm thinking the 30-40 c.i.d. upgrade isn't gonna make a world of difference, but the fact that the stroke is where the cubes are coming from may be where your getting the best increase for a doorslammer.

Picking up inches via stroke instead of bore I where I think you'd pick up a lot more bottom end grunt and the hp numbers would come from the inches that were picked up from bore size increase, so it looks like we think alike.

I was considering making the upgrade, but the additional cost to replace everything I have down bottom with the stroker stuff is hard to justify so far....

Did you consider a 10.5 to 1 CR., 582" motor using the 4.375" crank b/c it should be a brute!!

Again with a 288 street solid roller and Pro- type, big valve heads, (2.4"/2.0"), an 1100cfm carb. on a single plane and big regular headers open, you are at 846hp at 6500rpm and 779t at 5000rpm!!

WOW, eye poppin' power in my book....

And to think I just want a mild 588" one with a decent solid cam in it instead...

pdq67

pdq, as much as you like cubic inches, I need to get you to my buddy's shop sometime. They dyno everything from 555's to 632's daily. Those Brodix aluminum tall deck blocks with 4.75 stroke cranks, big dukes with sheet metal intakes and dual injection rails are sure nice looking setups. Watchin' 1100+ N/A horsepower strain against the engine mounts and dyno hook-up does something to me that nothing else ever has. These lucky dogs get to do it every day. When they look at you and tell you that it's just a job and it gets old after awhile, they all wink when they say it. I get to pick their brains all the time about combos, etc. and have saved untold cash. If you're ever in my neck of the woods (Lubbock, TX), give me a shout and we'll have more fun than the law ought to allow. Best thing is it's not our money screaming on the dyno!

Thank's for the invite if I ever get down that way MyBoTy..

Yes, I's just like when I was a kid. Blondes, brunettes and red-heads, just too many choices is all!!

But now I'm married and older, there's just too many Chevy motors to make and play with!! He, He!!!

Love them little-bitty, short stroke, stomp-it til it misses SB's and the brute power of the 406 SB and BB's...

pdq67