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Premium Member
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270 Posts
Discussion Starter #1
I am trying to figure out which Header gaskets I need for my #66 pontiac D port heads. The options are:

Large D-Port
1-1/8" x 1-15/16" D-Shaped Center & 1-1/2" x 1-15/16" Oval End Ports
PONTIAC Header Exhaust/Manifold Gasket

or

D-shaped center ports, 1-3/8" x 1-13/16" oval end ports
PONTIAC Header Exhaust/Manifold Gasket

Anyone know? The casting number for my heads is 481766
 

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376 Posts
Im confused, Is your cast number 66 or 481766? I found a part number 481760 which is for a head different from the 66 cast number head. If the heads are in your possession, just measure the D and Round port sizes to match them up with the gasket.
 

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376 Posts
For your info, I know on my 65 GTO and other years throughout the 60s that Pontaic did not put exhaust gaskets on. They machined everything flat and just bolted in on.
 

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64-67 Expert
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8,569 Posts
I hope you're running those heads on a 455 or 428.....they have big chambers, really big, and will net you super low compression on a 400 engine....
 
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