head gasket thickness
Thread Starter
Instructor
Joined: Nov 2005
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From: fall river MA
head gasket thickness
i have afr 195 heads with 58cc combustion chambers. if i use felpro 1003 head gasket . which has a compressed thickness of .041, that puts my compression in the 10.7 to 1 range. (stock bottom end l98). is the compression a little on the high side? if so what gasket should i use?
Pro
Joined: Apr 2008
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From: middle of Illinois
What are your intentions? 10.7:1 isn't all that extreme. Not too far off from a stock LT1 and they run fine on premium. I even ran 89 octane in mine one time in a pinch. (only open gas station for 20 miles was Casey's) Didn't notice any problems.
Thread Starter
Instructor
Joined: Nov 2005
Posts: 210
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From: fall river MA
i'm installing the afr 195 comp port heads ,tpis miniram and a comp xr276hr-12 cam. i know 10.7 to 1 on a lt1 isn't much , because of the reverse cooling. but wasn't sure on l98 thats going to be mostly driven on the street.
Le Mans Master
Joined: Sep 2006
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From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
my 86 corvette runs the factory flat top pistons, factory cam, with the 88 corvette aluminum factory heads. It rarely has a problem. Just when I nail it off idle. If I nail it after engine RPM's reach 1200 or so, it does just fine on 91.
It runs great up to about 3/4 throttle off the line, but the computer retards the timing after that.
Usually the factory runs a 14cc dish piston and runs regular gas with those heads.
I did the same combo on my 57 chevy pickup truck. It has a flat topped piston 4 bolt main 350 with '88 124 heads, comp cams 268 xtreme cam, edelbrock performer, and a holley 650, msd billet distributor with a 6a msd box, 86 corvette exhaust manifolds, 4 foot glasspacks with a short "H" pipe, and a corvette 4+3 trans, and 3.38:1 one legged rear. with p275-60-15 tires, 70 mph is 1900 RPM.
Without a computer to adjust the timing, on anything but 91, it will ping. then detonate..... On 91, it does ok.
But, the gas mileage is really good......35 on the highway straight and level in the vette, 23 on the highway with the truck.
It runs great up to about 3/4 throttle off the line, but the computer retards the timing after that.
Usually the factory runs a 14cc dish piston and runs regular gas with those heads.
I did the same combo on my 57 chevy pickup truck. It has a flat topped piston 4 bolt main 350 with '88 124 heads, comp cams 268 xtreme cam, edelbrock performer, and a holley 650, msd billet distributor with a 6a msd box, 86 corvette exhaust manifolds, 4 foot glasspacks with a short "H" pipe, and a corvette 4+3 trans, and 3.38:1 one legged rear. with p275-60-15 tires, 70 mph is 1900 RPM.
Without a computer to adjust the timing, on anything but 91, it will ping. then detonate..... On 91, it does ok.
But, the gas mileage is really good......35 on the highway straight and level in the vette, 23 on the highway with the truck.
Last edited by coupeguy2001; Dec 1, 2008 at 09:53 PM.
Pro
Joined: Apr 2008
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From: middle of Illinois
I put a 355 out of an 88 pickup with a mild cam and roughly 10.5:1 (used ported vortec heads off a 305 and KB flat top pistons) in a 91 camaro. It ran without a problem on anything 90+ octane. Under 90, it would ping a bit going up hills. That was the last Gen I engine I've owned, and I traded that car off in 2002.
