total advance ?

I saw this idea before... The advance in the centrifical advance plate is not divided by two. It has two weights because one would not be balanced as it rotates. You could remove one entire weight, and if the plate is stamped "18", you will still have 18° of mechanical advance. The reality of stock distributors is they have a ton of advance in the plate (the centrifical advance) and limited at idle for emissions and starting reasons. So generally, to get the initial timing the engine likes (and we like) you have to limit the centrifical. This is done by looking at the bottom of the advance plate. It's stamped with a number that corresponds o the total number of degrees it will move. (dist. must be disassembled for this) Usually it's between 18-30°. I use a percentage. If it's 24° total, and I want to be able to run say 15-18° initial, then you need to limit it to 18° (36 total - 18 initial = 18 centrifical needed). 18 is 25% of 24, so I'll weld up 1/4 of the slots. It's important to make sure the weights can slide easilly thru the slot after the welding. You can do the equivilent of any MP performance distributor for about $25. $5 for the light spring kit, and $20 to a muffler shop guy to weld up the slot for you.