3a heads vs 7a heads
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Registered User
Joined: May 2016
Posts: 17
From: Paris, Tennessee
3a heads vs 7a heads
I have a 350 olds engine in my 1986 olds cutlass when I bought the engine it came with a set of 3a heads on it I have a set of 7a heads off of a 307 engine from 1986. My question is would I be better off keeping my heads i have on my car or are the better ones the 7a heads. I have upgrades on my car. I have a edelbrock perkormer rpm intake, I have a thumper cam with a 2100 rpm stall, plus headers. That is NOT the big ***** thumper cam. Let me know what yall think. Thanks.
Old(s) Fart
Joined: Mar 2007
Posts: 50,815
From: Northern VA
Just so we're all clear, the 307 heads are the 7A heads. These have the tiny intake and exhaust ports that restrict performance on a 307, let alone on a 350. There are also 7A heads used on the 1972 350 motors. These would be a good choice, but don't confuse the two. Pretty much any heads where the "A" is the same size as the number are smog heads. If the "A" is smaller and below the number like a subscript, those are acceptable.
Registered User
Joined: Aug 2007
Posts: 2,250
Just so we're all clear, the 307 heads are the 7A heads. These have the tiny intake and exhaust ports that restrict performance on a 307, let alone on a 350. There are also 7A heads used on the 1972 350 motors. These would be a good choice, but don't confuse the two. Pretty much any heads where the "A" is the same size as the number are smog heads. If the "A" is smaller and below the number like a subscript, those are acceptable.
https://www.google.com/search?hl=en&...ha8Q88t-EVM%3A
Registered User
Joined: Apr 2013
Posts: 515
From: Wilmington, DE
Big fan of this head resource OP- Its a good mix of 'i've heards' and generally accepted Oldsmobile head principles.
http://www.442.com/oldsfaq/ofhed.htm
http://www.442.com/oldsfaq/ofhed.htm
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