Timing curves - any ideas?

Each engine is different. Your's might run good with 18° initial but mine won't hardly run there. My advance curve with 2 light springs might make your's ping. Really the only thing all systems have in common is the total advance within a degree or two. (around 34-5) You will need to tune the advance to your combination. Distributors are different but they basically work the same (advance weights held back with springs and limited with slots) Don't worry about vacuum advance until you get the initial and mechanical dialed in. There's a discussion about this going on right now. http://www.forabodiesonly.com/mopar/showthread.php?t=263737&highlight=distributor+curve

tmm