1973 472 exhaust manifold bolts ?

[Paradox]

What length size and thread pattern are the 1973 Cadillac 472 exhaust manifold bolts? I looked around on a few forums and nothing came up. two of mine are broken off inside the head so I want to buy a full set before I try to get any others out and possibly break more. Will lowes or home depot have them in stainless?

Why did they make it impossibly to get to these bolts as well <.< I have to try and get the wheel well off and maybe the springs and shocks because all of that is right up against it to where you can't get anything but a tiny swivel type ratchet on it.

[pyro]

I would just go with grade 8 bolts with an anti seize past. The aircraft industry uses milk of magnisia

[Paradox]

I plan on going with grade 8 stainless if I can get them but I need to know the sizes and thread pattern.

[Morella]

Grade 8 is not stainless, it is hardened steel alloy with a cadmium plating. Great for exhaust, though. Stainless would work too. Milk of Magnesia is a laxative...I believe we might be thinking about "mouse milk" instead, which is an anti-seize lube, although nothing much surprises me these days. For the installation, I would use either a high-temp anti-seize compound, or nothing at all. I would rather drill something out 30 years from now than have it come loose today, but that's just me.

I'm fairly certain that they are 3/8"-16 thread, but would have to double-check that. If you took them out with a 9/16" wrench, that is the correct size. *The* most important measurement is called the "grip length" of the bolt, and that is the length of the unthreaded portion of the bolt. This should be equal to, or very slightly less than the depth of the hole that goes through the manifold. So, just measure the depth of those holes in the manifold, or take the manifold down to the Grade 8 section at Ace Hardware, and get bolts that will fit through those holes so that the threads start on the other side, and the part of the bolt that is inside the manifold is not threaded, if that makes any sense. If they are a little too long, by aircraft standards, at least, you can use up to three washers under the head of the bolt to adjust the grip length, but you can probably get closer than that. I like to use a grade 8 (cad-plated) star lock washer and flat washer on exhaust bolts, although some manufacturors use locking tab plates. I think that either one is just about as effective.

-d

[tonytheskin]

Maalox can be used as anti-seize

[travlinman]

Just did this on My 72. Their 3/8 X 2 1/4 measured from under the head to the end. Have about 1" of thread. I broke the 2 front ones off, I was able to drill Them out in the car, real PITA but got Them with a very long bit around the A arm. Fastenall, if Yall have 1 around, is the best source around here for any type of bolts. I used a 6pt wrench and a 6pt short socket on a 3/8 break bar, too close for a ratchet on a couple. Good luck, You'll need it,lol.

[Morella]

Maalox can be used as anti-seize

By the same token, can you use Kaopectate instead of Loc-tite?

-d

[Paradox]

ok so If I go to lowes and ask for a 3/8in bolt that is 2 1/4th in long (under head) and 1in of thread they should be able to get it for me? or would they need any other measurements?

[travlinman]

Coarse thread. Ought to do it.

[northgahearse]

after the first motor with 2 busted in the rear
new game has been to just pull the motor out to get to them .. you know it needs new gaskets timing gears and some paint anyway.
motor number 6 is out now with 8 snapped bolts. in the past some crackhead shop i guess busted the head of the bolts off and then glued them back on oh what fun

but do as Morella said match them up and use washers i have yet to find the some size any place
goodluck

[Paradox]

I went to lowes and ace hardware. They have 3/8 16thread 2 1/2 but not the 1/4th so I could do the washers thing and it would work. They also had them for pretty cheap. it was under $1 per bolt. MTS seems to have the correct size bolt for $1.79 each in stainless.

[pyro]

If the military can use M ilk of Magnisia on million dollar jet engines as anti sieze, then you should have no problem using the stuff on your bolts. As far as torque, anti seize is not a locking agent. Torque bolts to specs and you will be fine. Stainless bolts will lock up if used with dissimilar metals.

[Paradox]

haha I have anti sieze that you dip the bolt into :P will it really last like 10-30 years tho? :P

I don't even know what the torque spec is on this :O

[Paradox]

Well I got some bolts to replace the broken ones and I am at a loss as to how to get the stuff in the way out of the way so I can use my air tools to bust these bolts loose and hopefully not break any more. Swivel sockets are to long to fit on any of these bolts.

Is there a secret to getting to these bolts on the 472?

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[Paradox]

I ended up unbolting that triangle shaped thing and can get to the bolts now and one came loose with the impact but the others will not budge.