Farmall Cub

My '49 has had the #1 exhaust valve lightly stick twice now, in the last few months. Its kept indoors, and the last time it was even in a heated shop. It just requires the removal of the valve cover and a light tap on the stem to get it going again. Just out of curiosity, I started the tractor up and watched everything running with the cover off. It was very cool. I'd recommend it. Oil does NOT get thrown everywhere and I could even see the crank spinning around through the openings into the crankcase by the lifters. My sons thought that was very interesting to watch.)
It was interesting to watch the valves do their thing, but what I noticed was that the oil is really coming out around the #3 lifter, slightly less around the #2 and 4, and very little around the #1. It doesn't look like that oil gets to the valve stem anyway, so that is probably irrelevent. I"m sure its just the relative position of the oil galley to each of the openings and proximity to the pump. The tractor is completely rebuilt and carries excellent oil pressure. The valves and guides were put in new and its ran for 2 or 3 yrs without ever sticking.

Anyway, why the #1 valve sticking? Is it something about its location in the engine and have others noticed when they have a valve hang up if it was #1 exhaust? I think I'll add a little MMO to the fuel and see if that helps it out a bit.

My guess about sticking valves. On shutdown, unburned fuel is left on hot exhaust valve stems so varnish/gum/carbon builds up down into the valve guide until the goop is plentiful enough to hold the valve open. My experience with other flatheads with repeatedly sticking exhaust valves required removing the offenders and cleaning both the valve stem and guide. Try shutting off the fuel and let the engine die of starvation.

I would dose it with Sea foam in the oil and the fuel and then run it hard for an hour of so. Plow pull a big heavy rock or log

OLD GAS WILL DO IT--------

Sea Foam or MMO treatment first. Lean out the carburetor low idle screw a bit. Check spark plug and quality of spark.

Next cheap try is to add a spacer ( .005" feeler gauge) between lifter and valve stem. Elevate valve to highest point - carefully rolling engine over by hand. Spray solvent through spark plug hole on valve stem. Roll engine over or backward to drop the valve - repeat process several times.

Still sticking - remove manifold. Same process as above but also use soft cloth with solvent to clean up exposed portion of valve stem.

Lurker Carl wrote:My guess about sticking valves. On shutdown, unburned fuel is left on hot exhaust valve stems so varnish/gum/carbon builds up down into the valve guide until the goop is plentiful enough to hold the valve open. My experience with other flatheads with repeatedly sticking exhaust valves required removing the offenders and cleaning both the valve stem and guide. Try shutting off the fuel and let the engine die of starvation.

I'd agree with you Carl, but I always shut down, (for periods of time more than say, an hour or so), by turning off the fuel. Its on a mag, so I don't worry about leaving the ignition on. The fuel in the tank is never more than a month old, as I drain the tank anytime its going to sit for very long. It usually only has a couple of gallons in it anyway, as I only put fuel in it when I'm going to use it. The gas you buy today is absolute junk so I never let it sit in any of my tractors that aren't frequently used, and certainly not in the carbs.
I've got my "siphon hose" readily available to drain tanks. I often find my self "robbing peter to pay paul" when it comes to gas around here. Most of the gas will end up in my old H or my JD 70 which do most of the chore work around here. And that 70, unlike its diesel brother, is not very frugal on fuel. Its just an overgrown G which had an incredible appetite for fuel. I used to joke than on a 1/2 mile row, you needed fuel cans at each end. Actually, joke wasn't the right word... "sarcastically lament" would probably be more appropriate!