I got a 620 thats lacking some hp on the dyno, only about 42 hp. We rebuilt the carb and tune up kit and adjusted the valves. It has some blow by and idles great with no stumbling during acceleration and runs great on the dyno. It seems like the distributor timing doesnt sound right. Current timing is 20 degrees at idle, which idles and runs great. But if we set the timing to 20 degrees at fast idle (WOT) it runs different at idle- labors. Using timing light. So what am i missing here, and what is the correct adjustment? The carb adjustments are, idle needles set to run at the fastest idle when shorting each cylinder out (1 - 1 1/2 turns out) the load is 3 turns out per tech manual.