1600 gas

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.

The whole time I was reading it I was thinking vacuum leak.

Thanks Randy. I'll ask him tomorrow if they checked for any leaks. Sure seemed like that to me too after the distributor.

stuck valve , lift valve cover and check

I would have thought that too or a bad valve. They said it was the same as soon as they fired it up after the head came back from the machine shop. The dad even said he checked valve lift to make sure there was no issue, not valve clearance, like adjusting the valves. All I know ow is what they told me so far. I have not yet helped them work on it at all. I will say one thing. If it was mine I could not run it the way it is. It would drive me nuts. I would park it and plant flowers around it. Seems like they gave up, and I'm just trying to come up.with some reason for the problem.

I?m thinking the same, at least from what I read.
I?d hook up a vacuum gauge.

On my 1550 gas I had intake manifold and distributor problems occurring at the same time.That was a lot of fun to figure out.Good used distributor and another manifold and
it ran like a top.Even though they worked on the distributor I'd be inclined to just try another one.For intake problems spray a little starting fluid around the manifold while its running,if it speeds up there you go.

The exhaust can rust out right over where the intake bolts on and let exhaust gas mix with the intake fuel making run as you described. BTDT. You can take the manifolds apart and put a sheet of copper between the 2 and solve that problem.

It's been a while since that happened to mine, but I think now it was the top of the intake that rusted out not the bottom of the exhaust. I sure whish we could edit our posts!!!

Randy,

Vacuum leak? I?ve never found one, ever!. Air leaks, yes, but never had a vacuum leak to anywhere. TBH, I say they simply do not exist.

That happened to my 1550.

Tell him to check and make sure he doesn't have an exhaust leak shooting fire to ignite anything,then take one of those little propane torches and slide a hose over it. Start the tractor and turn on the propane. Stick the hose around where the carb bolts to the intake,then to where the intake bolts to the exhaust and finally where the intake bolts to the head. If there's a leak,it'll suck the propane in and the engine will race.

I second Randy's suggestion, I had a Super 55 that wouldn't run correctly, I tried spraying WD-40 etc around and couldn't find a problem, propane torch found the vacuum leak right away.

Rich

Thanks for the tip Randy. Next time I'm over there I'll take mine along and do it with him. I'm just real curious about this one.