Ex. Manifold Bolts

[nate chase]

I would like to buy new Grade 8 bolts exhaust manifold bolts. Might as
well do it right. Mine are 7/16" head but I haven't pulled them yet to get
thread pitch or length. Can anyone help on the sizes here? It'll save a trip
to my uncles (storage place). I dunno if the small head is an improvement
here or not (I know sure hasn't helped me though!). The Hi-Collar lock
washers that came w/the Mr. Gasket copper gaskets are 3/8". Mr' G sell a new
chrome plated set for Olds 455 for only $21.95... ya, right!
Thought about allens but on second thought... nah! Too much motion
required even w/the ball tip wrenches (which truely are a god send). I did
that on a '49 Panhead rigid frame (H-D) I built in '73. Everything was
chrome plated allens and after I found out just how hard they are to use in
tight spots, I swore to myself never again. Bummer they didn't have ball
tipped allen wrenches back 25 years ago! Did get second place in mild street
custom in the auto show with but it was a royal pain to work on (especially
head bolts... now how do ya torque these babies down with 3/4" space to work
in!) and more of a pain in the butt to ride (no... I mean really a pain)!

Nate '75GB (Bolted... not screwed, thanks!) Omaha

 

[philip l. stewart]

> I would like to buy new Grade 8 bolts exhaust manifold bolts.....
> thread pitch or length. Can anyone help on the sizes here?
> Thought about allens but on second thought... nah! Too much motion
> required even w/the ball tip wrenches

Nate,
Thanks for the reply on which side the embossed face of the copper gasket goes
out.. (And thanks to you too, Rick.)

I read in Cinnabar's newsletter that the correct size of the manifold bolts is
3/8-16x1 1/4. Its interesting that you have decided not to use allen head
bolts. The same Cinnabar newsletter recommends them (grade 8 uncoated black)
but what they shipped me were the standard hex head variety. I previously used
the allen head bolt and as far as I could tell they worked fine and were not too
hard to install or take out.

In an earlier post you said that you would never use Anti-Seeze on a bolt. ( I
assume you were talking about the manifold bolts.) What's the reason for not
using Anti-Seeze? Thanks.
Phil Stewart
'76 Transmode, TN

 

[nate chase]

Phil,
Sorry if I miss typed but I wanted to say i WAS going to use Never Seize
not that I wasn't.
Thanks for the sizes. Allens would be easier to come by than the hex head
but either is too hard to get in the big "O".

Nate 75GB (Allen, no sorry... you must have me confused with someone else)
Omaha

>>>>
Date: Wed, 01 Dec 1999 20:39:04 -0500
From: plstewrt
Subject: Re: GMC: Ex. Manifold Bolts

> I would like to buy new Grade 8 bolts exhaust manifold bolts.....
> thread pitch or length. Can anyone help on the sizes here?
> Thought about allens but on second thought... nah! Too much motion
> required even w/the ball tip wrenches

Nate,
Thanks for the reply on which side the embossed face of the copper gasket
goes
out.. (And thanks to you too, Rick.)

I read in Cinnabar's newsletter that the correct size of the manifold bolts
is
3/8-16x1 1/4. Its interesting that you have decided not to use allen head
bolts. The same Cinnabar newsletter recommends them (grade 8 uncoated
black)
but what they shipped me were the standard hex head variety. I previously
used
the allen head bolt and as far as I could tell they worked fine and were not
too
hard to install or take out.

In an earlier post you said that you would never use Anti-Seeze on a bolt.
I
assume you were talking about the manifold bolts.) What's the reason for not
using Anti-Seeze? Thanks.
Phil Stewart
'76 Transmode, TN

 

[lorry clavelli]

RE: Allen head bolts vs. hex head bolts

On some headers, the exhaust outlet tubing comes very close to the
mounting bolt holes. In this case it may be difficult to get a wrench
on the hex bolt and the points of the head of the hex bolt may even hit
the outlet tubing. Allens would be easier to tighten and will generally
provide more clearance between the bolt head and the outlet tubing.

Speed shops sell header bolts specially made to help solve some of the
clearance and tightening problems.

Lorry