I went over to a buddies today to help him tow home a non running Farmall h he owns. We took his dad's 1600 gas to bring it home. The 1600 ran horrible. it has what sounds like a bad miss and runsrough through out the entire rpm range. The only time it doesn't have the miss and run rough is wide open under a heavy load. He said it's been that way several years and can't figure out the problem. I should also mention that his dad is a retired mechanic, and my buddy is a mechanic. They definitely know their way around a shop. Also farmers with a bunch of good running tractors. This is what they said they have tried. New plugs and wires. New cap, rotor,coil, condenser and points. Had the old distributor rebushed. Tried a different distributor. Had the head done with new valves, guides, seats and springs. Rebuit the carb themselves, then sent it out to be rebuilt by someone who specializes in tractor carbs. Then they bought a new/reconditioned carb. Replaced lines and had plenty of gas getting to the carb. Nothing that was done made the problem better or worse. This really made me think. With everything that was done I could only come up with a couple ideas. 1- bent push rod. 2- something wrong with the cam. 3- air leak at the intake manifold. Our 1650 gas kinda ran this way when the plate in the distributor was sloppy and couldn't keep the points adjusted right. I switched it over to electronic and the problem was fixed. Seems not the case with this one. Any other ideas ? Sorry post was so long, I just wanted to make sure I told everything I know.