Gino Faini, Framingham, MA, 1970 Plymouth Cuda 426
I have a 1966 426 Hemi engine in a 1970 ‘Cuda. The engine was just redone, new rings, bearings, guides, seals. My problem is, after a short time of driving the oil pressure goes down to about 15 to 20 from 60PSI, and when you let off the throttle it starts to smoke. I have about 575miles on the engine and it seems to be burning oil. Any help would be greatly appreciated.
Gino – There’s no magic. It sure sounds like two serious problems. If the oil pressure drops that low, unless you’ve done something stupid (like 0W20oil…), either then engine was built with too much clearance somewhere, or there’s tons of friction that’s heating the oil. I doubt it’s a pump-related problem, since that typically shows up even when cold. But if the pressure comes up when the revs increase, that might almost be livable, though not desirable.
But the oil burning, while there are a few possibilities, sure sounds like rings that never seated (rings in upside-down, poor cylinder wall surface finish, taper, out-of-round, etc.) This is very bad, no way to candy-coat it.
You didn’t say who assembled the engine, whether it was professionally bored, honed with a deck plate, clearances all checked, etc. Sometimes a driveway, 50-cent rebuild works out OK, sometimes…