[Walt Fricke]

Well, racers seldom pay a whole lot of attention to fuel mileage. Tune motor for WOT, and forget about the rest. The HPV-1 has four ignition timing adjustments: the base setting (which tooth is TDC, typically the trailing edge of the 11th tooth from the two missing teeth. Then what you add for idle, for an intermediate engine speed (3,000 rpm), and then 8,000. You can calculate where you want it to be at your shift RPM (usually below redline - redline is a safety/longevity number, not a shift point beyond 1st gear), and set the 8,000 additional advance so you will be where you want to be. The "curve" is actually straight lines from idle to 3,000, and from 3,000 to 8,000. Ignition does not know whether you are WOT or off the gas, though you can purchase a gizmo to give you some vacuum retard.

The 4th dial is the rev limit. Has nothing to do with the timing.

The simplicity and reliability with carbs are what it has going for it. No jitter in the timing from any mechanical clearances. These things are pretty important for racing. Not bad for street, but there you seldom are at WOT at all, and then not for long. Part throttle is where you are on the street..

The 4th dial is your rev limiter setting.