442craig

I'm putting a new exhaust system on my 68 442 and didn't get any exhaust pipe to manifold gaskets. Do they have a gasket on them?

Craig

nsnarsk65cutlass

No they have a tapered flange.

442craig

That's what I thought! Thanks!

76olds

Back in the day Midas would brush on some roofing tar around the inside flange before installation.

69442C

Craig, you may want to put a light bead of high temp silicone on the flange of the pipe especially if the exhaust manifold has any pitting. If you need some, let me know and I can get it to you. I have some left over from the 69 442 and I give it to you. Just as long as you don't need it tomorrow.

Brian

442craig

Thanks Brian,

It is my new Pypes system with new down pipes and the manifolds have been blasted and heat coated. Is the silicon an automotive application or can you find it at a hardware store? I am anxious to get it together, so I'll probably venture out to get some. Thanks for the offer! Another question on the same topic, do the manifolds have studs or can you use a bolt to mate the pipes?

Craig

rustyroger

That wasn't a dumb question. Dumb would have been guessing and getting it wrong.


Roger.

442craig

Thanks Roger! You are correct!!!!!

69442C

Hi Craig,

You should be able to find the silicone at your auto parts stores or even places like Lowes or HD. It seems the high temp stuff I saw on some automotive websites is by Permatex and is red in color. I guess if you used it sparingly, it wouldn't be seen. Interestingly enough, the silicone I have is not marked HI Temp and it was furnished by Gardner Exhaust for the repop system I bought from them. Lowes sells a gray Hi Temp FireStop product for use around fireplaces and that would also do the trick too. I would say if your exhaust manifold flange is smooth and not pitted, just try it without any sealer and see what happens. If it leaks, you can drop the pipe and add sealer although the driver's side is a little bit of a PITA with the starter in place.

The original fasteners were bolts for securing the pipe flange to the manifold. I believe it is a 3/8-16 thread but double check that. And I think the bolt will need to be around 1.5" but check that too.

Brian

442craig

Brian,

I used to use the copper stuff on the Corvair. They claimed it was good for heat transfer. Good on Carb to manifold stuff for heat transfer. Seems it would be good on the Olds. Maybe I'll try that just to be on the safe side! Don't want to have to mess with it after it's in! I thought it was bolts. I have a 3/8 16 holding it on right now. You have a good memory my friend!

Thanks!

Craig

69442C

I don't believe the copper stuff you mention is good for sealing as I don't know if it really hardens so you may want to lean toward silicone.

As for the memory, it seems to be working today but who knows what will happen tomorrow.

Brian