cylinder head question... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

68beater · 02-25-2003, 05:39 PM

When swapping cylinder heads: If changing from a 70cc head to a 76cc head, will this adversly effect the compression and longevity of the engine? Can this swap be performed without no driveability issues?

Xzavior240 · 02-25-2003, 05:44 PM

its going to lower the compression on it. and take away power if youre going to a larger CC head. as far as I know it shouldnt drive much different outside of pulling and passing and such just for putting around town or cruisin it shouldnt make much difference.as far as longevity its going to have less pressure on the cylinders so it may increase I dont know on that one

adamls · 02-25-2003, 06:58 PM

On a standard 350 (4" bore, 3.5" stroke) with flat top pistons .015" in the hole and a pretty thick gasket your looking at a 9.8:1 CR with 70 cc heads, that CR goes to 9.2:1 with 76CC heads, still pretty respectable. Send me your specs, you may be able to add the heads but still maintain your CR. That does not mean that you will have the same power because of flow capabilities of the new heads as compared to the old heads.

02-25-2003, 05:39 PM	#1
68beater Registered User Join Date: Feb 2002 Posts: 32	cylinder head question... When swapping cylinder heads: If changing from a 70cc head to a 76cc head, will this adversly effect the compression and longevity of the engine? Can this swap be performed without no driveability issues?

02-25-2003, 05:44 PM	#2
Xzavior240 Registered User Join Date: Oct 2002 Location: enterprise kansas Posts: 230	its going to lower the compression on it. and take away power if youre going to a larger CC head. as far as I know it shouldnt drive much different outside of pulling and passing and such just for putting around town or cruisin it shouldnt make much difference.as far as longevity its going to have less pressure on the cylinders so it may increase I dont know on that one __________________ 71 chevy C10 LWB 2WD runs and everything 79 chevy 1/2 ton Big Ten silverado gonna part it out since it left me walking. 69 f100 real good shape with lots of go go juice 89 plymouth reliant (daily driver) 86 thunderbird sitting in the weeds almost covered (anyone need parts?) WWW.xschunkofthenet.freeservers.com nothing there I promise " tell me I'm a sinner I got news for you. I spoke to god this morning and he dont like you" OZZY

02-25-2003, 06:58 PM	#3
adamls Gotta Startem Early Join Date: Oct 2001 Location: Amarillo, TX, USA Posts: 364	On a standard 350 (4" bore, 3.5" stroke) with flat top pistons .015" in the hole and a pretty thick gasket your looking at a 9.8:1 CR with 70 cc heads, that CR goes to 9.2:1 with 76CC heads, still pretty respectable. Send me your specs, you may be able to add the heads but still maintain your CR. That does not mean that you will have the same power because of flow capabilities of the new heads as compared to the old heads. __________________ 67 SWB In Progress, one piece at a time, maybe 3 years I will be finished

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