1958 641 Carb Adjustment

[fisheron]

I have a 1958 Ford 641. It starts and runs good and has plenty of power, however, it does run rich as the spark plugs are carbon fouled. It has a MS carb TSX593. That MS carb number does not look like one that was originally installed on a 641 (based on info I see on the internet) so maybe it was replaced at one time (?)

Would a carb adjustment be appropriate? I did check timing and it is correct.

 

[old]

First off when was the last time you cleaned the oil bath air cleaner cup?? Bet if it has been a while it is full of water and mud.
As for that carb my catalog says it should be on a 800/900 series tractor which has the bigger 172 engine so yes you may need to adjust the main jet which is the adjustment that sits low on the carb. Turn it in a bit till you have good power and no black smoke

 

[fisheron]

Thanks, Old.

I did clean the cup and replaced the oil in the oil bath air cleaner cup. I also removed and cleaned the steel wool filter element above the oil cup. Not sure how long since that had received servicing. The old oil had lots of dirt in it.

I will adjust the main jet as you suggest. Should this be done while engine running and at what RPM?

 

[old]

engine running and at about 3/4 throttle when you adjust the main jet. The take it for a test drive and if you can have it loaded down to make sure you have good power and no black smoke.

 

[Dean]

Did you check the air cleaner down tube?

Usually, these have never been cleaned and it is not uncommon to find one nearly mostly closed off with accumulated oily dust.

Dean

 

[showcrop]

The only true way to set your high speed jet is while under the load of a dynamometer. Since most people don't have one the usual procedure is trial and error under load, that is running it for a few minutes under a load, then stopping, or disengaging, then adjusting. This is repeated until you "feel" that you have the most power. Setting the throttle high is just a high idle so the engine is not working, and the butterfly will not be anywhere near all the way open. I had a shop mess up a carb on me. They put in too large a jet. in order for the tractor to run right I can have the main jet open no more than 3/4 turn. Your 641's plugs would probably clean up with a good load for a half hour.