Is it possible oil is getting into #7 cylinder from headgasket. Engine burns oil from left pipe only ,#7 plug oily . When it smokes it's bad at idle . SOME times it doesn't smoke at all. never smokes at start up. Oil returns seam clear. Compression test apx.120 in all cylinders but I forgot to block open throttle. Vacuum gauge reads steady 20. I'M waiting on leak down gauge that's still on backorder. When engine is running it's smooth. No pressure in oil fill when running. It does have pcv valve and it's new , also oil cap is plumbed into air cleaner . OIL pressure was 60 lb when cold with 15w 40 , I tryed 20w 50 and pressure is 80 cold. Pump is new within a year. Smoking problem didn't change with thicker oil.

62 f100 short unibody 292 big back window massachusetts

Steel shim or composition head gaskets?  Oil leakage into a cylinder is a possibility with a steel shim head gasket but haven’t seen it with the composition gaskets.  I’ll suggest a leak down test on the cylinder in question to help isolate the issue before pulling the head.

Lorena, Texas (South of Waco)

I believe it's steal shim. I did put shop air into cylider with piston tdc and I dId hear it through oil fill. how can I tell if it's getting past rings or through head gasket to oil passage.

62 f100 short unibody 292 big back window massachusetts

Is it possible he has a bad valve stem seal

No


  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Why not