harrisonm
Well-Known Member
I see people asking about how to finish factory exhaust manifolds on this forum quite often. They ask about what paint to use, how to prep, etc. Let me show you what I use and how I do it. You do NOT need a powder coating setup to do this process. I do, and it does help a little, but is not necessary. I will explain that in a few minutes. I know a lot of guys are going to say, "I didn't do that step, and mine came out fine." Maybe so, and I'll cover that also. REMEMBER, I am telling you how I do it. I am totally anal when it comes to surface prep and cleanliness. I have never had a problem with any paint, primer or powder coating separating or bubbling away from a surface due to my over the top prep and cleaning. It is possible to cut some corners and have good results, but you could also be setting yourself up for problems down the road.
Here is a before picture of one of the exhaust manifolds I did for a customer with a Chevy 83 Stepside. It was in pretty good shape. I HIGHLY recommend getting them sand blasted. Wire brush may get it looking clean, but it has to be clean. The wire brush will leave a lot of contaminants stuck to the surface and in cervices. I think is best to have them blasted. DO NOT have them glass bead blasted if you plan to use the special paint I use. It specifies it on the can. Glass beads leave the surface too smooth. That smooth surface may be OK spray can paints, but a slightly rougher texture will help the paint stick better.
After blasting they look like this:
Now I clean them thoroughly with Lacquer thinner and a microfiber towel. Blow them off with compressed air carefully to get any minute towel fibers off. There is no such thing as a surface to be painted being too clean. I bet every proficient painter on this forum will agree with that. OK, here is the paint I use:
Before painting, I put them in my powder coating oven at 400 degrees for 30 minutes to 'outgas' and burn off any impurities. You can use a regular oven. There is nothing that can cause any damage. However, you might want to do that step when the wife is going to be gone for a few hours.
I spray my paint on, but you can brush it on with a foam brush (just be careful to not get on too thick). I always spray on two medium wet coats.
After allowing time to dry, you have two choices with this paint:
1. Just let the paint dry and carefully install the parts on the engine. If you do cause a scratch in the paint, touch it up and let it dry. Then start the engine, let it heat up and then let the engine run for about 20 minutes (follow instructions on the can). That will cure the paint. DO NOT do it on a new/freshly rebuilt engine. They run hotter at first and the paint can be damaged. OR:
2. Do a pre-cure in a powder coating oven at 400 degrees for about 20 minutes. I don't think that is on the can. I called the toll free number and was give that hint. It helps harden the paint a little and shortens the time required for the engine to run during the cure. Again. this step is no really needed, but I always do it. Don't do it in the kitchen oven due to harmful gasses being released.
Here they are after my pre-cure. I don't have a picture of them mounted in the truck, but after about 3 years, they look the same.
Remember, this is just how I do it. There are a lot of other high temp paints out there, but whatever paint you use, be patient, prep well, no such thing as too clean and follow the instructions on the can.
Here is a before picture of one of the exhaust manifolds I did for a customer with a Chevy 83 Stepside. It was in pretty good shape. I HIGHLY recommend getting them sand blasted. Wire brush may get it looking clean, but it has to be clean. The wire brush will leave a lot of contaminants stuck to the surface and in cervices. I think is best to have them blasted. DO NOT have them glass bead blasted if you plan to use the special paint I use. It specifies it on the can. Glass beads leave the surface too smooth. That smooth surface may be OK spray can paints, but a slightly rougher texture will help the paint stick better.
After blasting they look like this:
Now I clean them thoroughly with Lacquer thinner and a microfiber towel. Blow them off with compressed air carefully to get any minute towel fibers off. There is no such thing as a surface to be painted being too clean. I bet every proficient painter on this forum will agree with that. OK, here is the paint I use:
Before painting, I put them in my powder coating oven at 400 degrees for 30 minutes to 'outgas' and burn off any impurities. You can use a regular oven. There is nothing that can cause any damage. However, you might want to do that step when the wife is going to be gone for a few hours.
I spray my paint on, but you can brush it on with a foam brush (just be careful to not get on too thick). I always spray on two medium wet coats.
After allowing time to dry, you have two choices with this paint:
1. Just let the paint dry and carefully install the parts on the engine. If you do cause a scratch in the paint, touch it up and let it dry. Then start the engine, let it heat up and then let the engine run for about 20 minutes (follow instructions on the can). That will cure the paint. DO NOT do it on a new/freshly rebuilt engine. They run hotter at first and the paint can be damaged. OR:
2. Do a pre-cure in a powder coating oven at 400 degrees for about 20 minutes. I don't think that is on the can. I called the toll free number and was give that hint. It helps harden the paint a little and shortens the time required for the engine to run during the cure. Again. this step is no really needed, but I always do it. Don't do it in the kitchen oven due to harmful gasses being released.
Here they are after my pre-cure. I don't have a picture of them mounted in the truck, but after about 3 years, they look the same.
Remember, this is just how I do it. There are a lot of other high temp paints out there, but whatever paint you use, be patient, prep well, no such thing as too clean and follow the instructions on the can.
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