Farmall 300 Carb

Anonymous-0

Well-known Member
Would someone please provide the settings for the adjusting screws on my 300. Freshly rebuilt and no specs. Thanks
 
Bottom screw front Load mixture adjustment 3 to 4 turns out from light seating. idle screw (left top about 1/3 to 1/2 way in (not critical at startup) idle mixture screw 3 turns out (or so)
After start, the idle mixture screw is adjusted for best speed then speed for 500rpm or so, then idle mix again, then speed. Power mixture should be set so (if warm) it goes from idle to full throttle in neutral without stumbling, and with very minimal black smoke or none. when pulling loads, it might be 1/2 to one turn out from there to allow full power. Jim
 
The info is in the operators manual. But, you need to remember that the Super H and Super M up changed their carburaters. The starting point for the main jet screw is 5 turns out, it can be turned in for lighter loads if you don't need full power. The carb is supposed to be set as lean as possible and still pull the load that you want it to. You do not want black smoke, and due to the design I doubt if you can get it. Jim is correct that you want to be able to pull the throttle back without stumbling, but my experience says that it will not pull any thing with the leanest setting you can get, in fact my Super H will not even go up a slight incline pulling nothing set like that. So, you will have to experiment. Instead of starting with about 3 turns out and increasing the mixture a half turn at a time, I start with 5 turns out and go a half turn in until it loses power.
 
Jim, I slipped up, I disconnected the govenor without noting how it fits in the front of the carb. Does the metal peg that extends out from the govenor fit in the small slot of the piece that controls engine speed,,,hope I stated that clearly
 
The tang goes in the slot. it is not impossible to do, but is finikey. Be careful as it goes together (use a good light) and it will be fine. Jim
 
Thanks Gents, I figured out how the governor connects and all is running well, I am getting some black smoke when I give it throttle, so I guess I need to adjust the needle at the front. thanks again
 

We sell tractor parts! We have the parts you need to repair your tractor - the right parts. Our low prices and years of research make us your best choice when you need parts. Shop Online Today.

Back
Top