The insides were another story. The water channels were pretty badly corroded and the exhaust crossover cover bolt holes seemed pretty bad. One had even corroded through to the channel and was full of dirt. The cover gasket had also perished.
This seems pretty dangerous as the carb is right over this hole. If it is leaking fuel and the exhaust happens to belch some flames, this could ignite the whole car. I could not find a correct new gasket so I bought a sheet of gasket material and cut out a suitable piece.
Then it was time to paint. I already had some POR-15 Chevy orange paint and Metal ready from when I painted my oil pan. Time to set up my sauna paint studio again!
I read some instructions and found that the POR-15 might chip off if painted straight on metal. To make it adhere better, I soaked the manifold with Metal ready. This should leave a layer of zinc phosphate on the surface and etch it a bit. After about 20 minutes of soaking, I washed the manifold with water and let it dry for a bit. When the manifold was dry, I brushed the first layer of paint.
It might not be apparent from the photos, but it was clear that another layer of paint was needed. The instructions on the can were a bit vague but I understood that the POR-15 needs to dry for 24 hours before painting it again. So I continued the next day.
Seems that POR-15 smooths out really nicely and leaves no brush marks. But this attribute also seems to cause it to retract from sharp edges. To get a good surface, at least two, most likely three, layers are needed. And even after three layers, I still had some small gray spots left. But overall, the result was really nice.
Unfortunately I ran in to small problems when I started to put everything back together. Some threads popped out from the EGR cover bolt holes when I started to tighten it. After that the bolts were too short to reach the threads with the gasget in place. Damn! I'll have to try to find a suitable helicoil repair kit for it or a longer bolt. That could be difficult in Finland...
Second problem was the heater hose nipple. Its threads in the manifold were in pretty bad shape too. I'll have to try to find a way to fix them too.
