Engine stalls when pressing in the clutch

[dmelcher]

I am about 90% finished with restoration on a 1950 cub. I replaced all the seals, new engine bearings and rings. Reused the clutch ,pressure plate and throw out bearing. Replaced drive shaft with new shaft because existing one was bent.
Cranked up the engine a couple of days ago and all is well. Today I decided to try for the first time to take it out for a drive. Engine starts up, went to press in the clutch and before I can get it pushed in all the way the engine starts to go under a load as I push it in farther the engine stalls out. Any ideas on what is going on??

[Eugene]

Ignition timing?

[tst]

is the clutch releasing, does the tractor roll freely engine off

[Glen]

Hi,
It is normal for the engine to slow down slightly when pushing the clutch pedal down fully, the throwout bearing doesn't turn.
Try greasing the throwout bearing grease fitting with cheap grease, so the oil in the grease can absorb into the graphite material.
You can wipe a small amount of grease on the front of the throwout bearing also. It helps reduce the friction of the fingers against the bearing.
Just in one place is good enough, the fingers will spread it around.
Use a small amount, someone said that theirs smoked when holding the clutch pedal down, after putting the grease on it.
I've never had any problem with the grease smoking.

The ignition timing needs setting correctly so the engine will have power.
If it has a Battery Ignition unit, the Cub service manual says to set it using a timing light.
A 1950 Cub probably has 1 timing mark on the front crankshaft pulley. Align the mark and the pointer when the engine is running at slow idle speed, 500 RPM.

The choke needs adjusting to the right position when the engine is cold also.

[Rick Spivey]

Potentially something is off in the engine tune. Timing has been suggested, also make sure you're not running on 2 cylinders, meaning the wire order could be wrong.

[dmelcher]

Thanks guys for all the responses. Engine does turn freely when it's off. I did have a timing issue when I first tried to crank it after reassembling the engine but did not check the timing with a timing light. I will do that. I did grease the throw out bearing zurk and will put some grease on the face of the bearing. After painting this tractor and having it beautiful I was afraid that I was going to have to split it in half to see what was going on.

[Don McCombs]

Engine does turn freely when it's off.

That's not really the question that was asked. Does the tractor roll freely back and forth, with the engine off and the transmission in neutral?

[Eugene]

Magneto or battery powered ignition?

Battery powered, did you remove the distributor when you overhauled the engine? If so you have to time the distributor to the engine, then the timing/spark?

Previously mentioned, two spark plugs wire on wrong plug.

Tractor ran last mowing season, before the overhaul.

Engine overhaul, did you remove the engine's front cover and perhaps get one of the gears out of time?

[dmelcher]

Engine does turn freely when it's off.

That's not really the question that was asked. Does the tractor roll freely back and forth, with the engine off and the transmission in neutral?

Yes.

[dmelcher]

Magneto or battery powered ignition?

Battery powered, did you remove the distributor when you overhauled the engine? If so you have to time the distributor to the engine, then the timing/spark?

Previously mentioned, two spark plugs wire on wrong plug.

Tractor ran last mowing season, before the overhaul.

Engine overhaul, did you remove the engine's front cover and perhaps get one of the gears out of time?

That was one of my biggest fears is that I didn't get the cam shaft in the correct timing position. But after having to remove the head to fix another problem I rotated the crankshaft and put #1 piston top dead even with the block and looked at the distributor and seen that I was 180 degrees off. Put the distributor in the correct position, reinstall the head and she fired up.

[Waif]

On the 53 I need to run the R.P.M. up a ways before take off after warm up.
After tractor has been working a while it'll be a lower throttle.
The amount of bog in depressing the clutch will be near the bog when letting it out in a higher gear too.
So, I'm running it by ear , but revved up well above a low idle for sure.

[MiCarl]

A couple of thoughts:

Where do you have the low idle speed set? If you've got it running too slow the drag from the throw out will stop the engine.

A misfiring cylinder will have the same problem. Mine wanted to stall depressing clutch at slow speed until I got ALL the running issues worked out. This includes ignition timing, fuel mixture and the last was new plugs to replace the ones that got fouled straightening out the fuel mixture.

[ricky racer]

Valve adjustment? Throw a quick compression check on it to see it there is a low compression issue.

[SONNY]

Just for giggles,---try reving engine up a bit before pushing clutch peddle down. also pull choke part way on just to see if fuel is the problem.
2 of mine pull the heck out of the engine unless I rev. the engine and if cold pull choke out a bit. after warm, not so bad.

[John *.?-!.* cub owner]

This requires 2 people, but try turning it with a hand crank while a helper pushes the clutch down. If the clutch causes serious loading look into the clutch assembly, or assembly of driveshaft and bearings. If only minor difference, check the above mentioned items.