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JIMBISK · 04-20-2018, 10:01 PM

I recently replaced the aging 350 in my 71 gmc with a BBC 454, peanut port heads, ZZ502 intake, mild cam and headers. low 8:1 compression with the current 121-122 cc heads. I have a set of oval port 063 heads with a 100.9 cc chamber closed chamber or a set of 113cc open chamber 241 casting heads from a 1972 LS5. I can't decide which set of heads to use to pick up performance. I've heard the open chambers while less compression than the closed chambers flow considerably better. But is it enough to warrant the difference between 9.4:1 (closed chamber) and 8.8:1 (open chamber). Any help on this topic would be great. also going from an SM465 to a 4L80E when doing the head swap.

04-20-2018, 10:01 PM	#1
JIMBISK Registered User Join Date: Apr 2018 Location: SANDY Posts: 2	Closed Chamber VS Open Chamber BBC heads I recently replaced the aging 350 in my 71 gmc with a BBC 454, peanut port heads, ZZ502 intake, mild cam and headers. low 8:1 compression with the current 121-122 cc heads. I have a set of oval port 063 heads with a 100.9 cc chamber closed chamber or a set of 113cc open chamber 241 casting heads from a 1972 LS5. I can't decide which set of heads to use to pick up performance. I've heard the open chambers while less compression than the closed chambers flow considerably better. But is it enough to warrant the difference between 9.4:1 (closed chamber) and 8.8:1 (open chamber). Any help on this topic would be great. also going from an SM465 to a 4L80E when doing the head swap.