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.