Napoleon1991
Well-Known Member
I’m having an issue with an extremely lean idle on my recently rebuilt 440. Its so bad that the engine will not idle on its own without the initial timing being set at 40 degrees. My A/F gauge shows between 16 & 19 when the engine is idling. It runs very rough and surges, but clears up instantly when I hit the gas. I have checked all over for vacuum leaks and even replaced the intake gasket with no change. The engine ran great earlier this year until I spun a couple bearings due to sucking the oil pan dry. The machine shop I took it to cleaned the engine, replaced the crankshaft and rods and rebalanced everything. The cylinders were honed and new rings were installed. I’m running the same pistons, carb, cam, heads and intake as before so nothing else should have changed. Before the rebuild my idle A/F ratio was around 14 and it ran great. I have tried swapping the carb and distributor with spares that are known to be good with no change. I did a compression test and all cylinders were in the 160s except cylinder 6 which was 148. Not sure why its lower, but I wouldn’t think that alone would cause the issue that Im having. Im running out of ideas of what to check for next. Any help would be much appreciated.