How to Paint Aluminum Engine Headsby Don Bowman
When painting aluminum cylinder heads, care must be taken to contain the paint to surface area only. No paint must be allowed to get on the spark plug threads, intake ports or intake mounting surface, any of the valve components or the bottom of the cylinder head. The heads must be perfectly clean and free of any oil or wax. Primer must be used for a base to support the paint. Engine high temperature paint must be used to keep the paint from lifting due to heat.
Tape the spark plugs with the exception of the threads. Install the taped spark plugs by hand only. Place tape along the outside edges of the bottom of the head so paint does not bleed under the head and on the surface. Turn the head upside down when taping the head surface. The tape will not hurt the head surface and is easy to remove. Paint however could be more difficult to remove and aluminum scratches very easily. Once taped, turn the head right-side up.
Place the valve covers on the cylinder heads and tape the base of the valve covers to prevent over-spray getting on the covers. Tape the intake port side of the head.
Paint the cylinder head with one coat of primer. Allow the primer to dry for 30 minutes. Paint the cylinder heads with two coats of paint. Allow two hours for the paint to dry before removing the masking tape.