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#1
03-31-2026, 05:51 PM
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Strange cylinder head bolt
The attached photo shows the cylinder head bolt located at the center exhaust port on my 66 GTO with original 093 heads. Just curious why the head of this bolt is made this way. Any ideas?
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Terry Hunt "He'd need 5 years in the fifth grade just to get an idiot certificate" Smokey Yunick re: Bill France Jr. |
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#2
03-31-2026, 05:58 PM
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I think they had a bulletin on it.
Seems like it was for heat maybe? (would have to look for it) I also think it was on some other year(s)? 1967? 
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! W.E.C moment "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
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#3
03-31-2026, 06:19 PM
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Strange cylinder head bolt
To help radiate heat away from the siamesed exhaust ports? Would love to see that bulletin. Interesting theory.
__________________
Terry Hunt "He'd need 5 years in the fifth grade just to get an idiot certificate" Smokey Yunick re: Bill France Jr. |
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#4
03-31-2026, 06:40 PM
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I have this:
Nothing about the heat though. Probably wrong on that. 
__________________
John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! W.E.C moment "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
| The Following User Says Thank You to johnta1 For This Useful Post: | ||
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#5
03-31-2026, 08:15 PM
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So Ironic. I came across one while going through some of my bolts and wondered the same thing. If anyone needs a singleton let me know.
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Green Bay: A drinking town with a football problem. |
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#6
03-31-2026, 10:16 PM
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I’ve only seen this extended head bolt used on 1966.
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| The Following User Says Thank You to 60sstuff For This Useful Post: | ||
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#7
03-31-2026, 11:25 PM
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Quote:
Please message me to let me know what you need for it and form of payment. Thanks. |
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#8
03-31-2026, 11:50 PM
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1966 with 093 head.
1967 with 670 head. |
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#9
04-04-2026, 12:51 PM
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Strange cylinder head bolt
“So that it may be properly torqued .” If all the other bolts with conventional heads can be properly torqued, why wouldn’t a conventional head bolt work in this location also? To quote Tom Vaught on these forums “Engineers do stuff for a reason.” but I can’t figure out what their reason is in this case.
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Terry Hunt "He'd need 5 years in the fifth grade just to get an idiot certificate" Smokey Yunick re: Bill France Jr. |
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#10
04-04-2026, 01:35 PM
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If you look at the photo of the 66 head the seat where the bolt head mates to the cyl head looks to be recessed. Thinking maybe the hex of a regular bolt would not work or you would not have much engagement with a socket. The special bolt moves the hex up to where a socket can grab it. Dont know why the head was machined that way. Also it looks like the protrusion for the AIR passage would interfere with a standard bolt head.
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#11
04-04-2026, 03:36 PM
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Quote:
It’s pretty obvious when looking at those two cylinder heads in post #8. |
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