Ford 861 losing power

[lilnoki]

I have a Ford 861 gas which I"ve had for several years. At first it was losing some power and running rough. My neighbor mechanic worked on it and found a blown head gasket. He cleaned up the valves and installed a new head gasket-everything was fine for a few years. The last time I used it last fall it was not sounding good again, and got to the point over the winter where I could not even use it. Compression tested out around 150 on all cylinders. Went through the points, plugs, and wires and all look good. Finally poured some Marvelous Mystery Oil in the gas and oil, let it sit and run sputting for a while until it suddenly let out a few good sputts then cleared up. Seems to have normal power again. However, I seem to go through something like this every now and then. It always seems like the exhaust smells like gas, and the exhaust blows very black on the draw bar. After a short while the plugs always look black as coal and covered with carbon. What"s wrong - valves, carburator, timing? My mechanic moved away. I like working on things myself but I"m no mechanic. Any thoughts ?? Thanks for your help.

 

[old]

Sounds like either the main et is set to rich or you need to clean your air filter out and change the oil in it
Hobby farm

 

[Jerry/MT]

Your carb mixture is overly rich so lean it out. Most carbs of this era are pressure balanced designs(the fuel bowl is vented to the carb air inlet) so a dirty air filter will limit your max power but not affect your mixture.

 

[El Toro]

If it has a main jet adjusting screw at the bottom of the carburetor you need to close it and this will lean out the mixture. Just close it 1/2 turn and try the tractor under load until that black smoke disappears. Hal

 

[souNdguy]

I agree with the others.. she sounds real rich.

soundguy

 

[lilnoki]

Thanks for all the help everyone, and thanks for confirming where the adjustment is on the carb. Gas hit $3.72 here today so I don"t mind leaning it out a bit.

 

[lilnoki]

Well, I thought I had it. I cleaned out the air cleaner and filled it with new oil. I ran the tractor a bit and warmed it up. I then gave the carb adjustment 1/2 turn in and sounded great instanly. I used it for a while and started missing and sputting again. Soon it seemed I was down to maybe two cylinders firing and then she quit. Had a hard time to get it started again. Tractor now barely runs, could hardly pull itself back to the shed in 2nd gear. So now what, valves? It seemed like when it was running good after adjusting the carb it still had a cyclical psh psh psh sound internally, kind of a blow-by about every forth firing. Any thoughts ?? Thanks !!