Tuning the MP 360/390hp

You cannot set total after setting initial, only check it.--EDIT crack beat me to it, unless the distributor has adjustable advance. This tells you how much mechanical you have, ie

you set initial, the mechanical advances to "whatever it is" and adds that on top.

You have to pull the reluctor wheel off, CAREFULLY use a screwdriver on each side of it, it's brittle, and the advance plate will lift off

Unless it's missing, there's a clip under the felt in the top. You have to have a VERY thin set of needle nose to reach it

Only way to change advance, unless it's an aftermarket adjustable unit is.............

change the top hat with one with shorter slots

weld and file the slots................

or there are a couple of aftermarket "advance limiters," I believe FBO and others sell 'em.

There should be a number stamped on your advance "top hat" probably underneath. That number tells you the advance in DISTRIBUTOR degrees. You multiply it x2 to get "crank degrees."

That is, if it's stamped "12", that's 22 at the crank. That means, then, that if you want say, 36total, you subtract 36 and 22 = 14 is where you would set initial to get that total. Just picking numbers out of the air, there