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Old 02-12-2014, 12:47 PM   #10
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Join Date: Jul 2000
Location: Justin, TX
Posts: 2,794
Re: Chevy High Performance 350- Fit or no fit?

Originally Posted by Jake Wade View Post
More like 7.8-7.9:1. One would be better off with the 260HP version with that paltry CR.
I agree 100%. Cylinder pressure with the bigger cam is very low. And that means low torque and not-so-great throttle response, certainly under 2500 RPM.

I don't know what GMPP was thinking, unless they wanted a lopey idle (misfires) and didn't care about loss of torque. At least they could have selected a cam with a tighter LSA, or cylinder heads with smaller combustion chambers. I think CompCam's #12-306-4 at 206/212 on a 108 LSA would work much better than the larger GM cam. You can also get it on a 110 LSA as #12-308-4.

On another note, I have had a couple 9.0:1 to 9.3:1 engines with iron heads, Neither one needed premium gas except on very hot days with coolant temp at 200-210. Of course, quench height on both was in the .040"-.045" range. On the GM crate engines it's .060"-.070", which is more prone to detonation.
1969 C10 LWB -- bought in 1989
1982 C10 SWB -- owned 2013-2020
Retired as a factory automation products salesman.
Worked part-time over the years for an engine builder and a classic car repair shop.
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Last edited by MikeB; 02-12-2014 at 12:59 PM.
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