Exhaust Manifold Bolts , Big Block

[1969grb]

I know I read a post about 69/70 exhaust manifold bolts for big block applications. I am having trouble finding it. Can someone help?
Thanks, Grady

[COPO CARTEL]

Try 427King.... Chuck

[thehornworks]

Still available from GM. Gary

[Unreal]

There are two exhaust manifold bolts available from GM. However, neither has the head markings that are even close to my originals.

[1969grb]

What I was looking for was information on the type of bolts used. I believe that on big blocks there was 8 shouldered bolts and 8 non-shouldered. I believe this was covered in another post but I can not find it. Thanks for everyones input, Grady

[olredalert]

-----Grady,,,I know Dick Fortier, the former owner of Paragon Corvette to be probably one of the most knowledgeable guys around about correct bolts for GM usage, specificly Chevrolet. Dick couldnt stay retired and re-started as a restoration bolt supplier. I cant lay my hands on a # or web-site at the moment and am in a crush to get a car ready for Carlisle, but hopefully someone else on here can get you contact info for him........Bill S

[Mr70]

Based on what I've seen,most 1969-70 Big Blocks including trucks,came with a longer shouldered bolt on the exhaust port end holes,(bolt #3909830 3/8 X 16 X 2&1/16)..and a shorter non-shouldered non-washered bolt on the inside holes,(bolt #3909821 3/8 X 16 X 1&3/16).
Also remember that what GM recommended an engine assembler to install vs. what that assembler actually did install,were not always the same thing.

[1969grb]

Bill, Thanks I had forgot about Dick Fortier. Got the contact info from NCRS. I will contact him next week. Grady

[nuch_ss396]

[ QUOTE ]
Based on what I've seen,most 1969-70 Big Blocks including trucks,came with a longer shouldered bolt on the exhaust port end holes,(bolt #3909830 3/8 X 16 X 2&1/16)..and a shorter non-shouldered non-washered bolt on the inside holes,(bolt #3909821 3/8 X 16 X 1&3/16).
Also remember that what GM recommended an engine assembler to install vs. what that assembler actually did install,were not always the same thing.

[/ QUOTE ]

I've heard this from some of the Corvette guys as well.

Nuch

[Woj]

I agree with what Rick (mr70) said. My car is unrestored (69 SS Chevelle) and when I removed the exhaust manifolds, the non-shouldered bolts were on the inboard ports and the shouldered on the outboard ports. I tried to put the shouldered ones in the inboards and they would not seat. The holes are not deep enough, at least on the heads on my car. The repops that are available today don't match what came on my car.

Hope this helps.

Phil Woj

[nuch_ss396]

[ QUOTE ]
I agree with what Rick (mr70) said. My car is unrestored (69 SS Chevelle) and when I removed the exhaust manifolds, the non-shouldered bolts were on the inboard ports and the shouldered on the outboard ports. I tried to put the shouldered ones in the inboards and they would not seat. The holes are not deep enough, at least on the heads on my car. The repops that are available today don't match what came on my car.

Hope this helps.

Phil Woj

[/ QUOTE ]

Phil,

Ok - there are eight bolts per side. If you numbered them
from one to eight ( L to R ), which bolts were of the shouldered type.

Nuch

[1969grb]

Nuch, Shouldered bolts would be 1,2,7,8 non-shouldered would be 3,4,5,6 Grady

[bluel78]

Did the aluminum heads use the same bolts?

[nuch_ss396]

That's a great question on the L/89 application http://www.yenko.net/ubbthreads/images/graemlins/dunno.gif

Nuch

[Woj]

Nuch,

Grady has answered the numbering question.

As I recall, the ears on the exhaust manifold are are of different thickness by about 1/16". The inboard ears are about 1/16" thicker than the outboard ears.

Phil Woj.

[JohnZ]

Corvette applications used a special bolt with a special self-locking thread form, P/N 3909821, and 3928905 for the location that included a threaded stud. AMK has the 3909821 bolts.

http://www.yenko.net/ubbthreads/images/graemlins/beers.gif