here in cali, the best they sell is 91 octance gas. is a CR of 8.3:1 sound good for my new 350 i am building? originally i planned around a 93 octane but i was mistaken and found out it was only 91 octance. whats the highest CR i can run on 91 octane?

 

8.3 is too low.

Aim for about 9-9¼:1.

I had a 400 for part of the time I lived in Carlsbad, with about 10.4:1. When I had originally built it I was very careful about "squish", deburring sharp edges int eh chambers, etc.; all the things one would do to make an engine tolerant of low-ctane fuel. I could get it to work out there, but I had to back the timing well off of optimum. So that is clearly too high.

 

305s and L98 350s mostly have 9.3:1 compression as IIRC, they run on 87 gas. There isnt any reason you cant bump it up a bit.

91 thats it?? Man I will never move there, Super smog laws + 91 gas = not as much fun/ more $$ to get the same results.

Im living in OH(for now), but back home in MI we can get 94 SUNOCO at the pump! Also, they dont test us for anything smog at all.

 

TraviZ - Still building a stroker?

 

yes..


all im waiting for is my tax return check.. then the fun begins

 

these pistons i had in mind had this ratio

# 64cc Head: 10.4:1
# 76cc Head: 9.1:1

and the heads i chose though have 70cc..

so that should come to 9.6:1 CR.. sound good eh?

 

Alum or iron heads?
It depends upon the cam too tho, but since yours is a TBI it'll be a small cam.
Zero decked?
KB has a good CR calculator, but they just updated their site so the link i have won't work, but if you type in kieth black pistons, it will get you there.
I'd think that with a TBI cam the CR of 9.5:1 or so is right for alum heads or lower with iron.

Did you get my PM?

 

http://www.jegs.com/cgi-bin/ncommerc...71&prmenbr=361

im assuming its iron

 

Those are aluminum.

9.6:1 should be fine with them.

The numbers I gave were for iron. With aluminum, you can get away with higher static CR; in fact, you need a higher CR.

 

ok thanks alot! that just answered my question perfect. but can i ask, where did u read that they are aluminum?? i couldnt find it.

 

I believe all sbc edelbrock heads are aluminum.

 

yup

 

ok then!