I've heard that you can get the initial timing by warming the engine up to operating temp, advance the timing a bit, let it idle a few minutes, shut it down, let it heat soak a couple minutes, and try turning it over. Advance the initial timing until you get kickback or it's labored turning over. Once it gets to that point, back off the timing a couple of degrees and that is now your initial timing.
I haven't had any success setting mine this way. It might be the MSDs I've been using, but I've had them up to 45+ degrees initial with no kickback using this method.
Here is
a link to a similar question, post 3 from crackedback outlines a method using a vacuum gauge.
