hopefully this will help you pick the right dizzy, or combo of parts for your engine.



the dizzy can be id'd by the casting #, the first 4 numbers on the dizzy body are the basis of the mazda number



N304: GSL-SE distributor. it gives 27.50 degrees of mechanical advance @4000rpm, dont forget stock setting is -5 BTDC, so total mechanical is 22.5;

leading vaccum advance is 5 degrees (not sure weather this is at dizzy, or engine) and trailing is 12.5. static timing split is 15 degrees, with full vaccum

split becomes 7 degrees



N249: 83*-85 12a distributor. this one gives 24.5 degrees of mechanical advance, by 4150rpms. stock timing is 0btdc, so this gives total timing of 24.5.

leading vaccum is 4.5 degrees and trailing is 15, with a static split of 20 degrees, this give full vacuum split of 9.5

*parts fische says 83-85, 84-85 for sure



N231: 83 12a dizzy (dont show it in the parts fische, but i have one, and its got a section in the fsm) this one gives 20 degrees of mechanical advance

by 3500, 4.5 of vacuum on the Leading, 15 on the trailing. static split is 20, with full vacuum you get 9.5 split..



N201: 81-82 12a dizzy. same 20 degrees @3500, static 20 degree split, 7.5L and 15T vacuum advance, gives you a vacuum split of 12.5



there are a couple more, didnt look at the 79-80's and i dont have the specs for the 12AT or the euro FC

advance numbers are stamped on the vacuum advance levers https://www.nopistons.com/forums/pub...#>/biggrin.gif

thanks!

Excellent info! Thats more mechanical advance than I figured.

yeah i know, i was kinda suprised