508 or 509 Purple Shaft cam

I know I'm a little late to this but I spent 30 years working at Mopar dealerships, even running a Mopar speed shop out of one. Anyway from Mopar there was a mechanical camshaft designed for oval track that was a .509 lift. The specs that momoparnut described are correct. Part # was P4529969. However it was not very common. More than likely you have the 508 hydraulic cam part# P4120233. Rusty Rat Rod's spec's are right on and he is correct; it is a big hydraulic. I ran one in my old Dart engine. Power does not come on until 3000 rpm, no vacuum at idle. Listen to his recommendations; he knows what he's talking about. There where misprints on the 508 and 509 numbers in the book; it is a .508 lift. For trivia as well: the spec's on Mopar Performance Purple Shaft cams are the same whether they're for a small block or a big block. You'd have to ask Larry Shepard about that.