Remember that the factory non-emissions static timing number is 17 degrees BTDC at the crank. A "typical" 240Z distributor will get you an additional 21 degrees of advance at the crank for a total of 38 degrees by 3,500 to 3,700 rpm. That was all designed for leaded fuel. Realistically on today's pump fuel you're lucky if you can get by with 32 degrees total at 3,500 to 3,700. That brings the static number back down to 10 or 11 degrees BTDC assuming the same advance curve. All of the above is without vacuum advance. I'm actually in the process of rebuilding and recurring a 240Z distributor as part of a little project. I'm going to try a build a digressive curve (more in earlier - starting at 1,500) and get 24 to 26 degrees of advance by 3,500 rpm (plus whatever static). So if you start with 5 static you'll get 31 total and if you start with 10 static you'll get 36 total. Luckily the Porsche shop across the alley from mine has an Allen Synchrometer distributor dyno. :-) EDIT: When I mean "typical" 240Z distributor, I mean ones that are 40 years old. I've tested a half a dozen and the actual advance curve is different then what's plotted in the FSM due to age, wear, gunk, etc. If you got to the trouble of tearing it apart, cleaning, media blasting, lube, etc. you might be able to get back to what the FSM says.