I would pull all the plugs and squirt some Marvel Mystery Oil in the cylinders. More than just some, actually. Plenty.
While the cylinders and rings are re-hydrating, I would drain any oil from the pan and replace it. Add a quart of MMO to the oil. Verify oil filter's condition.
Rotate by hand and see how it feels. Should be smooth and even. I'd do this as much as possible for as many days as practical.
I envision inside that engine surface rust, gummy oil, etc.... you know, the worst case scenario.
I have been running 20/50 in my 46 239 V8 and when I first start it up I have 50-60 lbs of pressure but after running it for a while it drops to 10-20. Is this a bad thing ? This is my first flathead and not sure if this is the norm for them or maybe ready for a new oil pump or complete rebuild.
I have been running 20/50 in my 46 239 V8 and when I first start it up I have 50-60 lbs of pressure but after running it for a while it drops to 10-20. Is this a bad thing ? This is my first flathead and not sure if this is the norm for them or maybe ready for a new oil pump or complete rebuild.