I would like to coat my 67 hp exhaust manifolds is there a company that does this has any one done this diy thanks

I've done it here locally at a place called Pro-Kote. it's ok but I don't think it lasts as well as when applied to tubing.

http://www.centralctcoatings.com/
They recently did my headers $200 less then jet hot!

I used Airborn Coatings in NC and was very happy with the results.

http://www.jetcoat.com/

Are you guys doing this mainly for looks, or does it improve under hood temps?

The ceramic coating will help keep the underhood temps cooler..atleast on headers it does.

I had a set of 340 manifolds done in a high temp powder coat that my local powder coater uses. They look great and they claim it holds up on manifolds...headers not so much due to them being thinner and getting hotter.

I wanted this done for looks mainly. Cast iron manifolds w/o anything on them look like crap after a while. This should last a long time and look good. I've never been happy w/ any of the spray can type of manifold treatment.

There seem to be powder coaters on every street corner, you can look in the Yellow Pages.

30 years ago I wanted to coat my Mercedes exhaust manifolds and I sent them to West Coast Porcelain in South ElMonte, CA.
They came back black and shiny.

Only problem is that the first time I stated the engine and then let it cool down, tiny cracks appeared all over the surface. Years later, the porcelain is still there, as are the cracks.

Now, with epoxy coatings the material seems to have enough give to deal with the thermal expansion.

R.

Used these guys on my stainless Viper headers 20 years back. They still look good.
http://www.headercoatings.com/