Heads: Can someone save me some work??? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

JimmyBum · 01-21-2003, 03:53 PM

I'm trying to buy new pistons for the 427 I'm building to replace my 402...only problem is the heads I'm gonna use are STILL ON the original motor <doh>. I need to know what type of heads I have to get the proper compression ratio with the new piston. The heads are 1970 402 heads from a 1/2 ton GMC pickup. Does anyone know if these original heads are open/closed and what size combustion chambers they have?? If one of you experts knows the answer off the top of your head, it would be much quicker than pulling a head off and trying to find the casting number...

Mega-thanks!! JB

01-21-2003, 03:53 PM	#1
JimmyBum Registered User Join Date: May 2000 Location: Yorktown, VA, USA Posts: 71	Heads: Can someone save me some work??? I'm trying to buy new pistons for the 427 I'm building to replace my 402...only problem is the heads I'm gonna use are STILL ON the original motor <doh>. I need to know what type of heads I have to get the proper compression ratio with the new piston. The heads are 1970 402 heads from a 1/2 ton GMC pickup. Does anyone know if these original heads are open/closed and what size combustion chambers they have?? If one of you experts knows the answer off the top of your head, it would be much quicker than pulling a head off and trying to find the casting number... Mega-thanks!! JB Attached Images __________________ //JimmyBum// `70 1/2T LWB GMC Sierra Grande; 402BB/TH400 `72 1/2T LWB GMC Sierra; 402BB/TH400 `88 Lincoln Mark VII LSC



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