Daughter needs Gas mileage from 273 commando

Yeah, I know; the dual plane with the longer runner length and the smaller runners should be better; all the lilterature for the single plane even in the day (mid 70's) said it was not as good for low RPM and drivability. But I hit the right combo with that and the smaller carb and torque cam. I was worried that I had blown my $$ on the single plane as a lowly Navy E4 but was really happy with the end result. When I can dig the 351C engine out from under the huge pile of used rally tires, I'll let you know; wish I could remember the model off the top of my head. I suspect the small primary barrels of the carb (Holley 6619 if I recall right) and the torque cam had a lot to do with it; that would keep the flow velocities up, even with the vary large intake stock flows of the early 70's 351C heads and the single plane. So the single plane was not a liability and I figure helped the top end flow to help make the RPM range so wide. Drivabilility for the combo was like a stock engine, never bogged or rough idled for a second; again, no foolin'.

Later when the headers rusted out, I was short of $$ and put the stock exhaust manifolds back on; sure stifled the power, and hurt the mileage.