A big necessary part of the criterior for the shop you choose to do the porting on your heads should be that they number 1, have a flow bench and #2, are familiar with porting Pontiac heads, especially if your looking for them to get more then 240 cfm out of the heads.
It would great if they can provide you with flow sheets of Pontiac heads they have ported as a reference.
I save flow sheets on every head I have ever ported (be they Pontiac or not ) unless they repeat previous results.
Also note that in terms of your 1959 389 heads they can not even BE ported to even 230 cfm @28”without making them prone to leaking coolant.
A later 389 iron head like a 1965 casting fitted with a 1.96” intake valve will go 258 cfm@28”.
In terms of iron heads for your stroker you need to run at least a 68 and up head.
Any big valve 68 and up head even stock ( but fully rebuilt ) should make you 370 to about 415 hp depending on how much Cam you run.
If you want more then 415 and not have to run a Cam that will kill your driving fun on the street the it’s time to port the heads.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs!
And he was not talking about 1/8 or 1/4 mile ETs!
1) 1940s 100% silver 4 cup tea server set.
Two dry rotted 14 x 10 Micky Thompson slicks.
1) un-mailed in gift coupon from a 1972 box of corn flakes.
Two pairs of brown leather flip flops, never seen more then 2 mph.
Education is what your left with once you forget things!
Last edited by steve25; 11-27-2025 at 06:31 AM.
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