I was thinking you might have a problem in your ignition system. If you're running points, I'd look there. Otherwise if you can convert to Pertronix electronic ignition, that might be better. You'd have to call them though to find out if there is a 12 cylinder application.

I sure would love to see a pic of that installation!


52 GMC 3/4 ton pickup
68 Big Block Vette
68 455 Firebird