C3 L-82 Aluminum Intake Manifold Sealing

[Paul Latour]

My recent purchase of a 1979 L-82 aluminum intake (#14007378) from EBay has turned out well. Thank goodness; you just never know. I sent it off to a machine shop that does local GM work. The intake has been bead-blasted, magnafluxed and it is straight and crack-free. They wanted to clear-coat but I said no. I have never seen a coat that does not yellow with heat.

In any case, I have a new GM t-stat housing (#14088753, I found a blind plug for the second hole), #14009008 TVS/EFE, #373510 TVS/EGR and the vacuum port for the TH350 is polished and just fine. I also have a set of #10147994 intake gaskets that Joe L. recommended to me two years ago for Al intakes. (I do procrastinate!) So things look good for install in the spring.

The question is, "Where do I put the Permatex 2 (or similar) to seal this intake?" Advice has been to abandon the rubber end seals and use Permatex. But what of the water jackets, exhaust ports, etc. Do I seal them down? Many thanks!

[Joe L.]

Re: C3 L-82 Aluminum Intake Manifold Sealing

Paul-----

I wouldn't recommend the use of regular Permatex sealers, at all, for the manifold gaskets. Use Permatex Ultra Copper RTV sealant. Use this sealer in place of the end seals and use just a very thin bead around the water passages, front and rear (even though the rear has no crossover, there are still the holes in the cylinder head). That's all. Don't use RTV at any other location; you don't need it.

If you do decide to use the rubber end seals, then place a dab of the RTV sealer at either end of the seals where they meet the side gasket "tab". If you don't do this, you'll have a leak, for sure. But, the best thing is to use the RTV in place of the seals and run the RTV along the block end rails from side gasket "tab"-to-side gasket "tab". After curing, you can cut away any "squeeze-out" with a razor blade.

[Paul Latour]

Re: C3 L-82 Aluminum Intake Manifold Sealing

Thanks Joe. I will follow your advice.

[Ralph E.]

Re: C3 L-82 Aluminum Intake Manifold Sealing

Should the same method be followed to seal a Cast Iron Intake Manifold?

[Joe L.]

Re: C3 L-82 Aluminum Intake Manifold Sealing

Ralph-----

100% exactly the same.

[Clem Z.]

i would also

"tin" the block and manifold suface before putting down the bead of RTV. "tinning" is taking your finger and rub a thin layer of RTV on both sufaces of the block and intake as this will make sure that the RTV bonds to the metal surfaces.

[Paul Latour]

Re: i would also

The more I read into this subject the more I regret having the intake manifold gaskets replaced three years ago by a "local repair" shop. This spring I will do it right: by me! It gets so frustrating at times trying to find people who do not get beyond computers 101. Thanks for the replies.