New Carb

Board shortener Tom

Board shortener Tom

Well-known member
Hi all!

Im currently doing some upgrading to Karla's 1955 LoBoy. It's run rich since we bought it, even after I rebuilt the carb a few years ago. The plugs are constantly having a buildup of soot on them so I'm going to a hotter plug. I've already upgraded (some might disagree) the ignition system to electronic. I've got the carb on the bench again and was about to crack it open. I checked on TM's website and saw that they offer a new carb assembled in America made of global and American components. I'm wondering if anyone can comment on how these carbs work on their cubs? I'm also going to be adjusting the valves and timing the ignition.

Thanks!
 
Here is a review on the TM Tractor Parts repro carburetor.

Don McCombs

Thread 'Reproduction Cub Carburetor Evaluation'

Tom, the owner of TM Tractor Parts and one of our sponsors, recently asked me to evaluate the new reproduction Cub carburetor that has recently come on the market. He also requested that I attempt to install a CaseIH rebuild kit, CaseIH idle tube and replacement IH float in the carburetor to determine whether the parts are compatible with the new carburetor. The following comments are the results of that evaluation.

In general, I feel the manufacturing quality of the reproduction carburetor is excellent. In fact some of the parts, namely the float, is of a better quality than the...
 
Don McCombs said:
Here is a review on the TM Tractor Parts repro carburetor.

Don McCombs

Thread 'Reproduction Cub Carburetor Evaluation'

Tom, the owner of TM Tractor Parts and one of our sponsors, recently asked me to evaluate the new reproduction Cub carburetor that has recently come on the market. He also requested that I attempt to install a CaseIH rebuild kit, CaseIH idle tube and replacement IH float in the carburetor to determine whether the parts are compatible with the new carburetor. The following comments are the results of that evaluation.

In general, I feel the manufacturing quality of the reproduction carburetor is excellent. In fact some of the parts, namely the float, is of a better quality than the...
Click to expand...
Thanks Don!
 
staninlowerAL said:
Did you change the main jet yet? Someone might have enlarged the main jet size. I think McDonald Carb and Ignition can help you with that. Check with Morgan McDonald. JMHO Stan
Click to expand...
Stan, I did not. I don't normal get that deep into carburetors. I have always just put a kit in them, change a float when needed and set the height. I've never messed with the jets. I've got a ton of projects on my plate with this old farmstead we bought and I don't have much time to fiddle around with things right now. My thought was to get a good replacement carb so the tractor is usable and get to the original carb when I get time down the road. I will check into this main jet thing and see what I find. Thank you for the info on this.
 
Board shortener Tom said:
Stan, I did not. I don't normal get that deep into carburetors. I have always just put a kit in them, change a float when needed and set the height. I've never messed with the jets. I've got a ton of projects on my plate with this old farmstead we bought and I don't have much time to fiddle around with things right now. My thought was to get a good replacement carb so the tractor is usable and get to the original carb when I get time down the road. I will check into this main jet thing and see what I find. Thank you for the info on this.
Click to expand...
Changing the main jet is a simple/easy task, it just screws into the carb behind the brass hex bolt on bowl on the choke lever connection side of the carb. If I remember right there's different sizes for the IH carb depending on the part number stamped on the top of the carb. Probably Morgan will know, also Bob McCarty and Don McCombs (and some others that I forgot). Using the wrong tool (like a tip cleaner) to clean the main jet can enlarge the orifice thus creating too large an opening/too much fuel flow. Stan
 

Attachments

  • carb & connections2.jpg
    carb & connections2.jpg
    26.6 KB · Views: 7
Last edited:
staninlowerAL said:
Changing the main jet is a simple/easy task, it just screws into the carb behind the brass hex bolt on bowl on the choke lever connection side of the carb. If I remember right there's different sizes for the IH carb depending on the part number stamped on the top of the carb. Probably Morgan will know, also Bob McCarty and Don McCombs (and some others that I forgot). Using the wrong tool (like a tip cleaner) to clean the main jet can enlarge the orifice thus creating too large an opening/too much fuel flow. Stan
Click to expand...
Thanks Stan! I will check this out and get with McDonald to see if this might be my issue. 👍🏼
 
Last edited:
i had to drill the jet out on my cub to get it to run! --still needs a bit bigger but it does pull now without killin itself. ---plugs white when i looked at them 100 hours later.
 
SONNY said:
i had to drill the jet out on my cub to get it to run! --still needs a bit bigger but it does pull now without killin itself. ---plugs white when i looked at them 100 hours later.
Click to expand...
Mine have a lot of black soot on them. If you touch the choke on this tractor it floods it. I checked the main jet today and it's right close to .032" so it doesn't appear to be drilled out. I have a question into McDonald Carb to see what they recommend.
 
before you blame the carb make sure the air cleaner is not full of debris or the inlet tube needs to be cleaned out, check points and timing and that the advance works on the distributor
 
tst said:
before you blame the carb make sure the air cleaner is not full of debris or the inlet tube needs to be cleaned out, check points and timing and that the advance works on the distributor
Click to expand...
Those are on the list although I didn't plan on getting into the air cleaner. I cleaned that about 2 hours of run time ago (3 years ago though). I will do a thorough check on the things you listed. Thank you!
 
Cubfriend said:
If you have mud dobbers in your area, that is plenty of time for them to work.
Click to expand...
There was a bit of crud on the inside of the downtube from the breather cap to the air cleaner. I pushed a rag through it and it cleaned out really nice. Everything else was clean and it was easy to blow air through the entire air cleaner setup in each direction. Now on to looking at those advance weights in the distributor.
 
put a timing light on it at idle TDC on the pulley, full throttle should be at the advance mark, if it does that its working as it should
 
Check your air filter and air inlet. There could be a restriction there.

I just fixed a pressure washer for a buddy of mine. He bought it running rough. Previous owner said it ran great last year. I cleaned the carb and dumped out the old fuel thinking it was the carb or bad gas. Still ran the same after. I removed the air filter for fun and it ran great! Bought a new air filter for it and then it ran awesome! The old plug was black as could be. The old air filter must have gotten oil or fuel on it and it swelled it up so it wouldn't breathe. Basically, the carb was not at fault, it was spotless inside. The engine simply wasn't getting enough air.
 
run it without the air cleaner hooked to the carb and you can see real quick IF thats the problem or not! -- if it still runs crappy then its not the air cleaner.
 
You must log in or register to reply here.
Back
Top