engine painting/prep

[240gordy]

what's the best plan for crankcase painting coating and cylinder heads etc? I have a lot of scale
inside and outside the case, and whats the best way to clean it up?
Any problem with powder coating the case or heads?

[theastronaut]

There are companies that can coat the heads with a thermal dispersant to help them shed heat better but if the engine is built properly it isn't really needed.

I wouln't powdercoat it and definitly don't sandblast/beadblast the block! It is ok to beadblast the heads.

If possible, get the case soda blasted to take the scale off and get it clean and then prep with PPG DX 533 Aluminum cleaner first.

DX533 is a phosphoric acid based cleaner,
brightener and prepaint conditioner for aluminum.
It is used to deep clean and brighten an aluminum
surface prior to welding, painting, or to prepare the
surface for a subsequent chemical coating. DX533
is clear in color.

After that, spray a light coat of PPG DP90LF on the block. This will etch into the metal and assure great adhesion of your top coat. Depending on the hardner you use, wait about two hours and then spray your top coat. Check the TDS to get the exact time between coats. If needed (when its cold), you can use a large enough cardboard box with a 100W inside bulb to preheat the block and also bake the paint after it's dried suffeciently. Using this method I've had smaller boxes up to 130F degrees.