Farmall Cub

Carb no longer drips. Tractor starts on the first pull of the starter. So I buttoned it all up and drove it out of the shop. Went into gear without trouble. There is a light grade outside the shop and it did not seem to throttle up like I would expect and by the time I reached flat land engine sounded like it was struggling. On the down grade I definitely heard and felt the engine braking and it drove down the hill smoothly but engine still sounded like it was working hard. At the bottom I stopped, it was clearly not going to drive any further so I took it out of gear. Continued to sound like it was under a way too heavy load then it smoothed out again and sounded good. Every time I push in the clutch, it goes back to the strained sound. Let it out and after a while it goes back to normal. I shut it down. Later I went back and it started but when I pushed in the clutch it stalled. When I say it sounds like it is straining or under a way too heavy load, I mean it sounds like an engine that was shifted into too high a gear or like a stick shift if you go from two to four and skip three. I call it lugging, but maybe that is the wrong term. Is this a governor issue? Didn't have time to look into this in the service manual. I feel like I am really close to having this one working good but it really keeps setting me back. Anyway, if you have any ideas I would sure like to learn what it is that is wrong. Thanks!

FYI...this was all in 2nd gear.

When mine acted like that it was a spark plug that got fuel fouled while I was working out a carburetor issue. A new set of plugs is relatively inexpensive and pretty easy to do, even to rule them out as the cause.

100% tune up starting with compression tests. Include valve tappet clearance, ignition/ignition timing, lastly carburation.

Dave H (MI) wrote: Every time I push in the clutch, it goes back to the strained sound. Let it out and after a while it goes back to normal

Based on this statement, I would look in the observation hole and check for any major clutch issues.

Throttle it up in first gear before releasing the clutch. Make it work in low gear and see what it does. If you are putting in second gear ,you are lugging it. If throttle responds correctly you bump it up when a grade/hill slows your progress. The governor works to up engine too under load , but there's a lag at times too that can be doggy if you don't throttle up.
Fuel supply or digestion come to mind ,but all components need to be in spec. and dialed in first.
The wrong plug wires and a host of other things could be causing it to dog.
Your clutch pedal play is set? P.T.O. disengaged? Clutch(and pedal) lubed? Brakes off? (Oh ,I been there with the brakes latched.)

I get an noticeable r.p.m. drop on one Cub when the clutch is pushed. One the other it is slight.
The one with the bigger drop is not a happy clutch that was replaced and never happy since. Worn hanger comes to mind , and pilot bushing being snug is another item causing shaft to spin a while before stopping with clutch depressed.

Lot of stuff there to look at. I had it split at one point. Maybe I better look at my adjustments again. I know the brake is off and PTO is disengaged. I don't think I have ever set the brake on it because it has rarely been out of the shop. Has just about new everything...wires, plugs, ignition parts, coil, ets. I will run thru the clutch adjustments in the manual see if any difference when I take it out again. Thanks for all the help!

Hi,
I sent you a PM.

How long was it sitting? Did you prime the oil pump? Oil pressure there?