Think about what the vacuum advance does, it pulls the advance plate to advance the timing. So if you turn the distributor the same directing the vacuum pulls, you will be advancing the timing.
These engines are pretty low compression and the fuel is better now then when the engine was designed, so you can get away with more timing today. I run mine at about 40 degree total, with out vacuum hooked up. I believe its 12 or 13 degrees at idle.
With the engine hot, unhook the vacuum advance and rotate the distributor till the engine runs its fastest and smoothest. This will get you really close. If it has a hard time starting, back it off just a bit till it starts OK. Once the timing is set, adjust the carburetor idle speed to slow it back down.
Joe
