I just went through this myself. There are three different points of timing you need to check. INITIAL - This is the timing set at idle with vacuum disconnected/plugged. It should be set between 0-18 deg. MECHANICAL - This is checked with the vacuum still disconnected and the RPM up to 3-4K to verify how much advance the flyweights within the distributor add. It should be between 32-36 deg. VACUUM - This is checked with the vacuum connected and RPM up to 3-4K. Should be around 50-52 deg. The more initial you add, the higher the mechanical/vacuum you will end up with. I bought this FBO Systems to limit my total advance and changed the springs inside to make sure I was completely advanced before 3K. You'll need a dial timing light Xenon Advance Timing Light if you don't have one since the timing cover only shows 10 deg BTDC/ATDC. You adjust the dial on the back of the light until the balancer lines up with 0, and whatever the dial reads is your timing.