Just installed a rebuilt 400 tough one from an auto parts store. Run motor for the first 30 minutes at 1500 rpm to lube the cam bearings well during break-in-in as recommended by tom's book. I think that number 4 exhaust value may be burnt. Engine misses and rough idle, very small but detectable (small tick like a value). Motor run very strong and mad oil pressure. Changed intake manifold gasket, which had no change. Will do a compression test at the end of the month.
1978 F-250 Camper Special 400 CID <O</OHolly 600 Vacuum secondary
Weined Intake Mallory Unilite (LED) Pro Sidewinder wires Daynomax Headers<O</O