Re: Cylinder Compression Questions

Posted by Fish'n Jim On 2014/11/14 21:49:25

Alot depends on how many miles are on it what good pressure would be. If cylinders are all pretty much the same, I doubt valves are stuck. Common mythology. You'll get really low values, like zero, if one's stuck open.
Valves may not be adjusted and not closing or opening fully giving lower pressure but it's difficult to get any meaningful pressure readings on cold rings even with the wet test. They contract and by-pass. Plus you need oil circulating to get the cylinder and head to pressure seal.
May want to start on a fuel cell if the tanks been sitting.
Old gas is trouble for the carb and pump.
If it's got the silly carb starter, by-pass it for now. Check all the wiring, etc. I don't like to even try to fire or put juice to one until all that's done first, so don't get to in a hurry.
Clean the oil pan or check for clean oil too. No sense circulating sludge if it fires. Replace all the fluids.
Concentrate on getting the spark good and the fuel mixture/carb doing it's job before you worry about the compression. Carb may need rebuilt, if it's dried out and new gas is in it. They'll fire if all that's right even if there's a few cylinders out, zero compression.