Painting iron heads on 400 engine
 

I rarely build an engine, but the Pontiac engines I have done, I've always mounted the iron heads and valley pan, then taped off the machined surface of the heads that the intake mates to. I then paint the non-taped area on the intake side of the heads along with the valley pan before attaching the intake. The same goes for the iron intake manifold. I had always kept it bare metal on the machined surface. It's only recently that I read it's okay to paint the machined surface of the intake as long as no paint gets inside the ports.

That begs the question of whether or not painting the heads mating surface for the intake would also work. It would be much easier than taping everything off and I would think it would also help prevent rust from creeping out from the edges of the gasket.

I can see many arguments for not painting these surfaces, yet I see posts in other forums where people say they have done it with no issues.

I appreciate hearing from those of you that have experience painting these areas and what the results were (are). If you have successfully done this, I appreciate any tips such as whether or not certain intake gaskets work better on these painted surfaces than others. Once this engine is done, it likely won't be cracked open again in my lifetime so I'm not worried if painting these surfaces makes it hard to get these areas clean again if the intake is removed.

BTW, no need to get into discussions about paint burning off the outside of the exhaust ports. I have plenty of bad :( experiences with that and how to make it better with high temp paint :) in that area before painting the Pontiac Blue.

Thanks
Old Joe

Its probably ok to paint those surfaces but I wont. The last one i did i trimmed my intake gaskets to where I wanted them. I then wrapped the gaskets in tin foil and lightly bolted them to the head. then painted it.

I have an extra set of gaskets in the fel-pro kit I bought that are spares so I was thinking of possibly doing something similar by just bolting those in place, taping over the port holes in them and then painting . The downside is it still doesn't stop rust from creeping at the edges of the gaskets that are used in final assembly.

I’ve painted the intake ( and exhaust) mounting surfaces for years. I put tape over the ports, but keep the tape line under where the gasket will seal. The engine will look better in a few years of running this way. I do lay down a couple of thin coats. You don’t want it too thick, bit that’s the case with the whole engine.

I did this on the engine in my profile pic, and it still looks good 5 years later.

I have painted both flanges at times.

First I prime the whole head with a high heat silver header paint then I paint the head.

On the intake side before bolting the manifold on I apply a light film of wheel bearing grease and then just adhere the gasket to the manifold.

On the exh side I coat both sides of whatever I amounted to using for a gasket with a film of anti seize .

Using the high temp paint first to prime the heads is a plus because it does not burn off from the tops of the exh ports or the crossover are and allow rust to start.

This means that touching up those areas with more paint is a breeze.

Is there any particular brand of high temp paint that you found works best for the coating under the pontiac blue? I've had very good luck with Seymour and VHT rattle cans, but read that POR15 was pretty good too.

I thought about that technique as well, but always wondered if the added few mils of paint thickness under the edges of the gasket compared to the unpainted area would cause a leak over time. Can't argue with the success you've had. Thanks for posting this.

VHT is what I have always used.