Back in the early days of Quarter Midget, the engines had throttles. The K&B .15 used a Perry, and I think the Rossi's were also fitted with the same though that was done by the importers or distributers. Those engines had milder timing, because at that time the rules required the engine to idle. The later engines did not have that requirement, and the Cox (modified by Young???) and at the end, the Nelson dominated the event. Neither will idle very well with a throttle.

QM models flew pretty well, and were only slightly faster than a Rossi powered quickie. Put a 6x5 or 5 1/2x5 1/2 prop on it and let her rip.