Painted up the engine, the NicPro paint I bought from Amazon worked fine, so it must've either been my mixture ratios or surface prep on the last build.
I'd intended to use the old "Pacemaker Grey", (one of the oldest bottles of paint I own, easily 30+ years, I painted my fiberglass shark with it then, and then Pegasus shark last Summer) worked great then, but no matter how I thinned it, it kept clogging my airbrush.
I can only guess it's so old there are particulates in it and they just kept clogging the nozzle.
I needed to pivot and as I was looking for an alternative color, found this; Vallejo Black Metallic, and talk about a happy accident!!
What a fantastic color. I'm going to have to paint something else with it. It's a gunmetal, though more grey than black to me. It's pretty close to the paint of my actual GMC and their Irridium Metallic.
Anyway, removed the masking and no leaks, (I sprayed a nice even coat of white before I sprayed the top coat and that really seemed to help.
I'll give the paint the day to dry and get back at it tomorrow morning with some assembly and detailing, painting the pulleys, belts, etc.