1976 L-48 Head flow
Thread Starter
Intermediate
Joined: Jul 2008
Posts: 30
Likes: 7
1976 L-48 Head flow
I was wondering what the cfm and flow numbers for my stock heads on my l-48 are. I also want to know what the valve size is for intake and exhaust. Also i was looking for a good stock upgrade for a 383 im building. I was wondering what car models and years i might be looking for heads off of.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,114
From: Crossville TN
If you are going with a 'stock' steel head, you can't really use a head with more than 9.5:1 compression using today's 93 octane fuel...or you will have a spark knock (pre-ignition) problem. So, that limits your choices to the '71 & '72 LT1 heads or later L82 heads...all of which were 9.0:1 compressions. With a thin head gasket you could get that up to around 9.2:1. You could also go with 'stock' L98 heads which are 9.5:1 and much better flowing; but you would also need an intake that will fit the L98 heads (stock GM intake or aftermarket unit will fit on your engine block), as well.
Last edited by 7T1vette; Sep 28, 2009 at 07:10 PM.
Le Mans Master
Joined: Dec 2003
Posts: 5,727
Likes: 38
From: Fremont CA
If you are going with a 'stock' steel head, you can't really use a head with more than 9.5:1 compression using today's 93 octane fuel...or you will have a spark knock (pre-ignition) problem. So, that limits your choices to the '71 & '72 LT1 heads or later L82 heads...all of which were 9.0:1 compressions. With a thin head gasket you could get that up to around 9.2:1. You could also go with 'stock' L98 heads which are 9.5:1 and much better flowing; but you would also need an intake that will fit the L98 heads (stock GM intake or aftermarket unit will fit on your engine block), as well.
Race Director
Joined: Dec 1999
Posts: 19,610
Likes: 778
From: Forked River NJ
To rework a set of decent stock heads yo uare going to be in the same price range as a new set of better heads. It does not make any sense to rework stock heads unless you are NCRS. The cost of new heads and the performance of them far outweighs redoing older heads.
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Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
To answer your original question:
.100 56/57
.200 108/77
.300 157/110
.400 180/125
.500 187/133
You don't want to put any time or effort into stock, "vintage" GEN I heads; the return is small and you're really not saving any money.
I've taken heat for this before, but if this is a MILD 383 a stock set of Vortecs will feed it to 5200 RPM or so. Without more details on the build, it's not possible to say.
You need to give more information to get a useful answer to your question.
.100 56/57
.200 108/77
.300 157/110
.400 180/125
.500 187/133
You don't want to put any time or effort into stock, "vintage" GEN I heads; the return is small and you're really not saving any money.
I've taken heat for this before, but if this is a MILD 383 a stock set of Vortecs will feed it to 5200 RPM or so. Without more details on the build, it's not possible to say.
You need to give more information to get a useful answer to your question.
Safety Car
Joined: Aug 2000
Posts: 3,711
Likes: 43
From: San Antonio TX
I can find no fault there. That's what Chevy did with the HT383 package. Seemed to work out fine for them.
Le Mans Master
Joined: Jun 2004
Posts: 6,231
Likes: 65
From: Seattle WA
St. Jude Donor '14
