A vacuum leak from the crankcase to the intake bypassed the restrictor plate- - - -more air- - - -higher RPM. I did something similar on the claimer engines I built- - - -1/2" diameter countersunk Allen bolts holding the carburetor adapter to the manifold- - - -with a 1/4" hole drilled down the middle of the bolts. The Holley #7448 350 CFM 2 barrel the local rules required was an attempt to hold engine building costs down- - - -no point in building a big bucks engine if it can't breathe. No matter what the gear ratio was, a 355 cubic inch small block Chevy couldn't wind tighter than 6100 RPM- - - -no matter what cam, valves, heads or other go fast stuff we tried to use. (A big air leak past the carb- - - - - -however- - - - -) all the race was going to decide was who would run second, half a lap behind the guy running one of my engines!
Jerry
