[GRN69CHV]

Definitely mkae sure you are running plenty of timing. I bolted on the 870 I have that is destined for the 502 motor just to move the car around. Surprisingly, even with 78 primaries, it was not that rich. 74 -75's in the front would probably work a little better. However, even with all that extra fuel available off idle inclding a .040 nozzle, it still has a hesitation from idle. I am inclined to want to dive into the timing issue myself. I am inclined to think, the change in timing from full manifold vac. to mechanical advance is severe enough to cause a misfire and hence the flat spot - not fuel related. I have also heard guys running upwards of 40* total with closed chmaber heads - with 20 built in that would require about 20 initial. I know it seems severe, but it just may be that these motors need all that timing, especially when we add more cam.