Ford 640

Hey Y'ALL I notice when I'm running my bush hog, if I hit a thick spot of grass or heavy brush that makes the tractor work hard, I notice some black smoke coming out of the exhaust pipe. It runs fine with no black smoke out the exhaust when under normal operation, how would would I get the most horsepower out of the old girl. Would leaning the fuel/ air mixture help? If so how would I adjust it?

Thanks for any help.

Justin

I also pulled my plugs today, they we're black and had black deposits on cylinders 1 and 4, if this helps

Start with a complete carb rebuild.

Tim Daley(MI)

As Tim said it probably will need to have the carb rebuilt, but if that needs to wait until winter you could try turning the high speed needle in a little. It is the one on the bottom of the carb at an angle. Just 1/4 turn at a time. Your problem could also be the float level too high. There is a recent thread that shows putting a barbed adapter with 6 inches of clear vinyl tube on it into the drain hole on the bottom. With the tubing pointed up the level in the tube will be the same as in the float bowl.

Clean the air cleaner.

Make sure that you clean the accumulated dirt from the down tube inside the air cleaner. It is not uncommon to find these tubes nearly closed off from accumulated dirt.

Dean

Just started cleaning my air filter, noticed that on the back there was some markings that said it was from an NAA tractor, it was pretty nasty, don't know how to clean the mash inside without taking it out, I'm afraid if I do take it out I won't be able to get it back in.

You must remove the mesh in order to properly clean it. Wash it thoroughly in solvent. I use gasoline as there is nothing better but I am well experienced. Of course, I do it outside of my buildings.

Do not uncoil the mesh. It can be properly washed without uncoiling. It is not difficult to reinstall the mesh once cleaned. Make sure that you remove all of the mesh for cleaning.

Inspect the inside of the down tube with a flash light. You will likely find that it is very much restricted. There is no easy way to clean the accumulated dirt from the inside of the down tube. I usually remove the air cleaner assembly and scrape out the biggest part of the dirt with suitable probes before finishing up with suitable wire brushes. You will likely be amazed by the amount of accumulated dirt in the down tube. I've seen down tubes with air passages of approximately 1/2" diameter. Any wonder why such tractors run rich under load? Nobody (OK, there is probably someone out there who does) inspects and cleans the down tube.

Do not mess with the carburetor (other than obvious issues) before thoroughly cleaning the air cleaner.

Post back with results.

Dean

Well Dean, I did what you said, I cleaned the air filter, pulled the mesh, cleaned and reinstalled, wow there was a lot of dirt build up in there. I just came back from brush hogging my deer trail clipping that are about knee high and thick, saw no more black smoke out the exhuast, at one point I stalled the tractor there were so much clippings, also noticed my temperature guage read 180, did not go any higher, thanks for YA'LL help

Sincerely,
Justin

Glad to help, Justin.

Change the oil in the air cleaner every year or two. Clean the cup when you do so. Inspect the bottom of the mesh when you have the cup off. You may not need to clean the mesh again for decades, unless you do lots of mowing in tall cover and in dry conditions.

Dean