Don't waste your time re-painting. Last year (thanks to a CAC member) I was the winning bidder on an Ebay auction for original LT-1 exhaust manifolds. I had them painted and put on my car last spring, and it was just a matter of a few weeks before the paint was pretty much burned off - and this work was done by a guy that restores corvettes for a living - his work is 1st class.
There are some products you can use to keep them looking freshly painted, but they're usually very messy. You can order these products through mid-america, Ecklers, etc.
After removal have them blasted with a medium red garnet media in a blast cabinet, as much as I could on the inside and CLEAN CLEAN CLEAN on outside. If your not going to have them refinished right away your going to have to treat the clean metal with a metal etch or its going to rust within a few hours. There are only two coatings I have found that hold up over time. The easiest and cheapest way to go is a product form the Eastwood Company called, StainlessSteel High Temp Coating #10364Z. I have used this before with very good results on a 340 Dart Swinger restoration. Having them ceramic coated is also a very popular way to go. If your going to use the Eastwood system have them resurfaced before coating and don’t touch the resurfaced area with paint. If going the ceramic route, have them resurfaced after coating is applied. Always use new hardware that is of proper grade and new exhaust gaskets, and doughnut. It’s just like painting anything else; the final results are only going to be as good as the surface that is underneath it. Always wear latex gloves when handling clean parts. http://www.eastwoodco.com/jump.jsp?itemID=732&itemType=PRODUCT Brian
BarryK, a member of the CAC sent me a "pm" a couple of years ago about a product and procedure he used on his car. Here's what Barry sent me - if it comes out as nice as Barry stated, it's a LOT easier than pulling the manifolds:
sorry, I can't currently take and send you any pics of the exhaust manifolds because the car is in the shop getting a new paint job.
If you saw the thread in which I reported using the Dry graphite Film Lubricant the pictures don't do the product justice - they came out looking very nice in my opinion. Better pics of the results can be seen on Paul79's car in a current thread which is here http://corvetteactioncenter.com/foru...ad.php?t=57399
The second pic in the first post in the thread (the green car) is Paul's and the graphite spray use was his idea that I had used.
I can say that the exhust manifolds on my car look just as good now after approx 1000 miles of driving as they did when i first applied the graphite spray - there is NO change what so ever to how they look. It's not wearing off or baking off from use. The only thing I have found is NOT to use a heavy-duty engine degreaser cleaner such as Gunk on the manifolds after applying the graphite spray. I found this out the hard way - a day or two after initially doing the mainfolds I decided to clean up the rest of the engine and used a lot of Gunk cleaner to get a very clean motor. The Gunk removed some of the graphite causing a "spotting" look. I reapplied the graphite spray and now only clean the motor down with water or more mild cleaners and rags and the exhaust manifolds continue to look very good.
A friend of mine also used one of the other products on the market designed for exhaust manifolds but also like you found that it didn't last very long. Using the Dry Graphite Film Lubricant was very easy, very inexpensive, and is lasting a long time. I believe in one of his previous threads Paul79 said that so far it's lasted 2 years for him without having to re-do them.
Even if I do have to do them again in a year or two it only takes about 20 minutes total for the job and a little more than 1/4 can of the graphite which only cost approx $4.00 so any possibly reapplication in the future won't be a major hardship!
The graphite I used is from NAPA is is called NAPA dgf123 Dry Graphite Fil Lubricant.
You can also find this under different names. One of the important things is to make sure it's the aerosol can AND the contents also include propane.
To apply, spray some from the can into a cup until you have a bit of a "puddle" in the cup. Immediately dip a small paintbrush into the cup and than paint it onto the exhaust manifolds. You will need to work fast and also not spray too much into the cup as the propane causes it to dry out very quickly. After one or two dips into the cup and painting onto the manifolds spray more into the cup and continue.
Don't be concerned when you see the graphite in the cup and first on the manifolds. It will look very dark black and MUCH darker than desired but as it drys it turns to the dark gray color you see in the pic.