Farmall 400 Update

My post about my 400 is back page or so, so I'll start another. Gas motor, fouls the spark plugs in an hour or so run time, very cold blooded. The shaft in the distributor was sloppy, so I replaced that with a new set of points, condenser and plug wires. I was using it yesterday, so I shot some starting fluid around the intake manifold with no change is how the motor ran, so the intake is not leaking. I did a compression test on it. First reading is just after running it for a few of minutes. #1- 110# added 10 squirts of oil, still 110# #2- 110# added same amount of oil, 115#, #3 110# added oil 115#, #4 110# added oil 125#. Each time I cranked it over 10 times until the needle stopped moving. I have non foulers on all of the spark plugs. I went thru the carb a couple of times and finally took it to a guy in the tractor club that runs a repair shop and has many old tractor for him to rebuild. I finally got it adjusted to where it runs fairly decent, but it black smokes like it is running very rich. On cold start up, it smokes blue for a bit. I'll pull the valve cover and check the tappet settings, but it has a loader on it, if I have to pull the head, I'll take the loader off first. I'm think it needs new rings. It doesn't get run very long at a time and I have nothing to put a load on it to make it work hard. Chris

Does it warm up with the short trips, maybe not, you can make a reducer for the thermostat housing bypass,so it doesnt bypass so much! This is Janicholson idea, and i made some for my tractors,it does help,once you get the thermostat apart you will see how big that bypass is,almost as big as a corn cob, make a plate and drill a 1//4 inch hole in the plate!

Black smoke it is rich. Does disconnecting the air cleaner change anything?

When does it black smoke, idle, under power, both? Does it drip gas if the fuel is left on not running?

Blue smoke on start up is valve guides. Blue smoke under load is rings, but need to get the fuel right before making decisions about repair.

Is the main jet adjustable? If so turn it in until it won"t take sudden throttle from idle without stumbling, then start backing it out 1/4 turn at a time until it will. You can load the engine with the hydraulics, curl the bucket and hold it, just don't do it for very long.

If it still black smokes with the main all the way in something is still wrong with the carb. If nonadjustable main it may have the wrong jet.

Sounds like my SM. It blows blue sometimes and black when being speeded up. I know it needs rings and a valve job. It was stuck when I got it, but it broke loose with some ATF and air pressure applied to each cylinder. I tried to lean it out but that just made it run rough. I'll re-ring it someday

Haven't tried disconnecting the air cleaner yet, I'll do that. It black smokes a little at idle and when opening the throttle it smokes like a diesel not under a load. I had to run with the choke out in order to accelerate without stumbling and dieing. I have opened the main jet a little at a time until it accelerates good but black smokes when wide open. Carb doesn't leak when shut off.

The package for non fouler I had warned to not use them in all the cylinders. I ignored it and put all 6 in my IHC scout engine. Well guess what they were right as then I could not even get it started. Went back to just using it on the worst ones.

There is a lot of old stuff that has had the thermostats removed, when what was needed was to clean the radiator. Cold engines need more choke to run,the rich mixture washes the oil from the cylinder walls, causing ring and cylinder wear. On the 400,I would do rings and rod bearings(pull a couple of the maine's to check them) and go through the head at least to check the valve guides.

that engine is not that bad. cover the rad if its not getting warmed up with the little use. what plugs are in it now? what are the carbs setting now? main jet on bottom should be at least 3 turns out.your just doing loader work so try 2 1/2 turns out as you say its black smoke. i have many running with 2 1/2 turns out. its in the field under load you need 4-5 turns out. its fully off the seat at 5 turns out. idle mixture i always find 3/4- 1 turn out is where it ends up. good idea on the valve set, .017 hot. plus on a compression check 5 puffs is good. you want to pay attention to the first 1 or 2 puff's as you get your most compression there. plus you need the points set to .020 and the timing set. that thing will run like a swiss watch at 400 rpm idle.

ooh and check the air cleaner oil for dirt and water, as that may be it . have seen 560's not start because of frozen water in cup.

Is the fouling on the spark plugs oil or fuel? Dumb question: is the idle circuit in the carburetor clean and adjusted to idle smoothly? I ask because it might be idling on just the power circuit which would be too rich.

Plugs are oil soaked. I had it out this morning, this is what I get when I open throttle all the way.

I screwed the screw in until it died, then opened it until it would go wot without stumbling.

Next up is to drain radiator and see if it has a thermostat.

Slow ignition timing can cause problems similar to yours. Your engine is not in bad shape. Many of the older tractors ran 50 to 80lb. compression. Also, your oil add test is good. If you have access to a dwell meter, hook it up and run engine through the rpm range to be sure you don't have a distributor issue messing with point adjustment. Point adjustment will affect timing
Otherwise, possibly hotter plugs or a little higher octane gas. Gas should not make a difference, but, if I run Lower octane fuel in my pulling tractors than was used to tune them out, I will get some black smoke. Sounds like it is something that you have overlooked

you are over fueling, way over fueling. what is the main jet set at on carb as i asked? maybe the float is heavy also as it has gas in it. try another carb if you can. its easier when you dont know what to look for in that carb. and at that rate you are washing the cyl's down. its nothing to do with the thermostat. plain as day whats happening. cold engines dont do that either. plus thats not oil on the plugs. its unburned gas. they must be black as you know what.

also have you checked the choke and air cleaner???

Black smoke to me means carb.A hole in the carb float will make it pour black smoke.

I forgot to add, the tube from carb to air cleaner was off when I did this. Put it back on, no change. I don't have a different carb to try.

I'll add a few things that I haven't seen mentioned yet.

First thing is your compression readings do not indicate a problem with rings. The only reason I could see for oil consumption coming past the rings would be if the gaps were all lined up. Since it ran for years previously without excessive oil consumption, that would rule out problems with the rings.

My gut feeling is that you have a problem with the head. Worn out guides, bad guide seals, or a combination of both of them.

For the black smoke, my best guess is either the float level is too high or there is a porosity in the body. Fuel is getting where it should not be going. As others have said, smoke like that comes from too much fuel.