Issues painting sheet metal Options

[dbgriffith75]

So as I'm rebuilding the engine on my 914, I've been repainting the sheet metal with, and I know it's not the best way but my budget is limited, spray paint. Not just any spray, it's Dupli-color Engine Enamel- a ceramic rated to 500 degrees. Problem is, the primer gray is showing through no matter how many coats I put on it. One piece must have about 20 coats on it and still the gray is showing through. I finally got to the point where I said screw it and sprayed on a really thick coat on one piece, telling myself that when it cured I'd just sand out the runs and put on a lighter top coat to finish, but even that isn't working. Any ideas if it's just the paint, or maybe I should just switch to a black primer? Thanks.

[dbgriffith75]

There's no chance there's any oils or lacquers like that on the sheet metal. Besides using gas to clean all oil and grease off (if needed, not all of them did), each piece has been cleaned thoroughly with a wire brush, then sanded to get rid of as much surface rust as possible, then wiped down with a clean rag, and then blasted with air just to make sure there's no dust on them. I've put a lot of work into prepping the metal itself before spraying on the primer.

I appreciate the advice, and any more y'all can give me is welcomed, but at this point I'm going to get some black duplicolor rustproofing primer and try that. The primer I'm using now is rustproof, but I think the problem is that it's a light gray and for some reason the black just isn't drowning it out.

Thanks again.