I bought a Farmall 100 last year that wasn't running. I had the head done, new rings, put it back together and ran pretty good as long as the choke was about 90%. Asked several questions here and we all thought a vacuum leak - never found one. Fuel is fine. One thing it did do is sometimes it would get a cloud of smoke after running a few minutes. I never ran it much and it didn't happen when it first started. I was out of ideas but winter came so I parked the tractor for the season. This spring after winter storage I found the radiator level low and took out grayish looking oil. Now I'm thinking a coolant leak. Can't tell about bubbles coming back to the radiator as the level is down just enough I just see return liquid form the water pump. I'm planning to check compression and do a pressure test this weekend. My question is what is a good compression test considering there are new rings and valves and what pressure should I pressurize the cylinders to. I didn't see anything in the cylinders when I had it apart so I'm real hopeful all I need is a new head gasket and sealer but I'm not normally that lucky. I'm thinking I didn't put a sealer on the head gasket when I installed it.