66 standard exhaust manifolds - Pontiac GTO Forum
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post #1 of 4 (permalink) Old 03-03-2015, 09:39 PM Thread Starter
 
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66 standard exhaust manifolds

I have the original log manifolds on my '66 GTO 389, they are showing their age. I recently came across what look to be a really good clean set that is being advertised as being removed from a '68 GTO. I know Pontiac used the same manifolds with the same part numbers from 65 to 68, without date codes. My left manifold has the part number 9779032-2, the "new" set has 9779032-1. This is the only difference I can find on this one. My right manifold is where I'm seeing a noticeable difference. My manifold 9779328 GM 4, the new one same part #, GM 3. My manifold was cast with lugs on the exhaust ports centered between the bolt holes where they mount to the head, I'm guessing for added strength. The "new" manifold is smooth. Is the difference in castings just because they came off of a different casting machine, or a revised design from 66 to 68? My big question is if I buy these manifolds to use, when it comes to judging at POCI or GTOAA, would they be correct, or would it be noticeable they came off a different car? After owning the car for 20 years, I have now become anal about making sure the car is as it was when it left the factory, save for a couple of bolt on options that I have added. Thanks for any help. Scott
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post #2 of 4 (permalink) Old 03-04-2015, 12:45 PM
 
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Sorry I can't answer your question regarding the newer manifolds. I am curious when you say your original manifolds are showing their age. I restored my '66 GTO to "as original condition". The original manifolds looked bad but were not cracked or broken. I took them to a shop that cleaned them and then ceramic coated them. They look great and will never discolor. Worked great for me.

1966 TriPower, 4 spd, PHS documented.
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post #3 of 4 (permalink) Old 03-04-2015, 05:06 PM
 
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Biggest issue I've had raised in inquiries from customers when asking about and shipping out original Pontiac V8 (non RA) exhaust manifolds, is rust pitting. Many original exhaust manifolds are rust pocked badly, just not worthy of use in true (read national) show quality restoration. On std ex manifolds, unless theyre really something rare, if they're pitted bad, I've usually chunked them when processing parts cars and engines. The Lh ex manifold on the '64-67' V8 Pontiac A body's has always been a good one to stock, as that's all it fit, not a B series or '67 F series. If your intention is showing the '66 and having it judged in GTOAA Concours judging, the replacement LH manifold would be fine. The passenger side though, needs to be correct design and casting number. What is the passenger side casting number looking for? sorry, do not have Eric's book in front of me.
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post #4 of 4 (permalink) Old 03-04-2015, 10:00 PM Thread Starter
 
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Thanks guys. I guess what I mean buy showing their age is the pocked marks, I guess is what you are calling it. I won't say they are rust pitted, but the best way I can describe it is it looks like there were air pockets in the mold, rough to the touch. This is on the right manifold, the left one looks and feels a lot smoother, so I guess the biggest issue is with the right manifold. Would the prep work that goes into ceramic coating the manifolds help smooth them out somewhat?

The pictures that I have seen of the other set of manifolds that I was thinking about purchasing looks to be a really nice set of castings that don't show any signs of pocked marks. My biggest hang up on buying these is the right manifold came out of a different casting mold. The shape and the part number matches up, but does not have lugs cast into them on the front and rear runners. Let me know if pictures would help, it will be this weekend before I can get over to my car to get some.
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