ANOTHER SBC STROKER QUESTION 377-

[joespanova]

I'm entertaining going from a 3.48 to a 3.75 stroke in my 377. This car weighs about 3000 me on board. The car has run a 9.30@144. It's a manual trans deal , drag race only. Tunnel ram , 23 degree heads , all the usual "bells and whistles".
My "experiment" is to go to the 3.75 crank because , for one , anything longer with aluminum rods will be a hassle. The added stroke gives me about a full point of comp. , in this case going from approx. 14-1 to 15-1. No dyno on my 377, but calculators predict about 700ish.
So who wants to share what I can expect IF the only thing changed is the stroke? The cam in there now is around .278/.288 , .760/.740 on a 109. I realize the cam may have to be changed a little. Headers are 1.875 to 3.5. I'll use the same pistons , just shorten the rod by about .125.
So initially , just adding stroke...then we'll talk about cam.
Predictions ??

[bobmc]

going to need a smaller base circle cam if you have a standard cam height block

[joespanova]

going to need a smaller base circle cam if you have a standard cam height block

I'm already using that. Anyway ........

[Carnut1]

I like the experiment but I wish we had a dyno sheet to start from. My wag is some power from the compression increase, the shorter rods and increased piston speed will be a wash power wise. The increased cubes and stroke will move your torque peak down a bit. It will be interesting to see if your shift points change with the torque curve moving a bit. The question of air demand being satisfied with the heads and tunnel ram comes to mind too. Bigger engine with the shorter rod will give the intake a different yank. I will be reading along, forgive my stream of consciousness thoughts.

[SpeierRacingHeads]

IMO with the shorter stroke and the 5 speed, it will be much happier than with the 3.750 stroke.

Myself you need a different cam in what you have. If the heads are any good, it has way too much cam in it.

My opinion.

[F-BIRD'88]

It will go faster......

[Stan Weiss]

Just to get an idea of what is going on. At what RPM do you shift?

Stan

[joespanova]

"IT WILL GO FASTER" , "IT WONT GO FASTER", the parasitic loss will offset the stroke.......geeezus , no wonder I can't commit.
"Intuitively" I think it will be faster. Don't understand why Chad thinks it has too much cam , if anything I would expect the @ .050 intake to INCREASE slightly and the lobe centers to spread a degree or so.
The limitation is the cast tunnel ram , Victor Ram. The engine is spun as high as 8800-9000. The shift light is set at 8.
I will add this...........to all the "predictors" that believed the new intake seats would pick up the car , I ran my best times and MPH with 45 degree seats ( intakes ).........not the new 50's. So that's one exercise I wish I avoided.
I would have expected the added stroke and compression to only BENEFIT the engine.

[joespanova]

It will go faster......

OK , so we have 1 in the "it will go faster " camp....

[SpeierRacingHeads]

I have customers with 377's or 380's that make 680+ and we are running 260-268ish cams and peaking at 7300...

Few guys running the same sized engine peaking at 8200 with 272-282ish cams

Again, it's all about how good the head is.

One thing for sure, what I have might not compare to your combo. I guess the bigger cam engines are close to what you have.

[RevTheory]

Joe, unless the heads are already stretching molecules, I don't see how your plan could be a bad move.

[joespanova]

I have customers with 377's or 380's that make 680+ and we are running 260-268ish cams and peaking at 7300...
Few guys running the same sized engine peaking at 8200 with 272-282ish cams
Again, it's all about how good the head is.

One thing for sure, what I have might not compare to your combo.

I have an old Jay Allen grind where the @.050 intake number was like 267 and the ex was a traditional number ...like say 288ish. The difference between that cam and more common grinds was inconclusive at best. The design offering the "more area" ex. as the rationality ( in the 267 cam ) for the short @ .050 number. I understand what you're getting at........but I have to wonder how those ( yours ) would stack up against mine. At 3000lbs to run 144 , you can decide and do the math. Allens thought was the cam would rev so quick I 'd have to change the shift light , LOL.

[SpeierRacingHeads]

I know this isn't making as much power as yours, but it's cool nonetheless.

365 cid with 227 CNC heads and a 260/268 at 3300 lbs and 5 speed Jerico.

Gotta love the leave!

[joespanova]

I know this isn't making as much power as yours, but it's cool nonetheless.

365 cid with 227 CNC heads and a 260/268 at 3300 lbs and 5 speed Jerico.

Gotta love the leave!

Nice.
My heads are approx. ( give or take a drop ) 255 cc. I poured them myself

[Ron E]

Joe, unless the heads are already stretching molecules, I don't see how your plan could be a bad move.

That's what I'm thinking too. But, if your 377 is running out of head up high, you'll get a tiny bit more torque and HP at lower RPM. If your heads can stand more motor it's going to get better. (runs good now, BTW)