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Pontiac of the Month

31pontiac's 1959 Bonneville

2019 December
of the Month

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Been checking with all the experts on which heads are best for a 455...6x???why are these so popular ? seem to have better low speed port velocity  but lees velocity than my 4x at maximum lift..talked to my machinist said maybe try a set of 46 heads off a 350. has better high lift velocity than the 4x and the 6x with a 96cc chamber volume.He suggested replacing intake vales with 2.11 and installing  screw in studs which could also improve low speed velocity. has.anyone tried this combination? would appreciate any advise

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This is a new one on me. I am surprised your machinist is recommending the 46 head. It was installed on both the 350 and 400 motors with either a 96cc or 98cc chamber. The part that puzzles me is the 46 head had a 1.96 intake valve and a 1.66 exhaust. So machine work is required to move it out to a 2.11. There are so many other Pontiac cylinder heads out that that are already 2.11/1.66 or 2.11/1.77, so why pay for the machining if you don't have to.

On my '72 Leman's 455, I run a 7K3 set of heads (off a 400). They are already 2.11/1.77 factory head. It has a triple angle value job and some light porting work to improve flow. Nothing radical. ARP studs and bolts are used through the motor.

This list from Wallace Racing might be better suited to your needs / wants. The nice thing is that most of the Pontiac heads are interchangeable.


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Thanks Frosty for your reply,but you misunderstood my question anyone  tried these?? Now if you want to give me a price on your 7k3 heads i would by willing to buy them. since there is an  abundance of Pontiac heads in your area  . What i want to do is put them on my 73 GP, and  I dont want to go through alot of port work. these heads are the ones I have .  and they have better  velocity with a 181 cfm at .500 lift than any of the heads like 6x, 96 ,66,64,48 do you see my dilemma?? So i pretty much can see no one has tried this, I will keep you posted on the outcome

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