C carb help

28sstony · May 10, 2009

Ive got a C that has just refused to start run smoothly this spring. I did a plug change and had a look at the points and rest of the guts in the distributor and it all looks brand new.

I rebuilt the carb (marvel fixed jet) and set the idle adjustment screw per the instructions. When I go to start it It will crank, fire, sputter a few times and die. The choke position seems to have little effect in how long it runs before dying. Once it finally started last night I had to back the idle adjustment screw way out so the tractor would stay running under load. This morning Im right back to the sputter and die when starting. Any advise on what to do before I trash the starter?

Jeff Z. · May 10, 2009

First thing to do is make sure you have a good steady gas flow to the carburetor.
Second is to check the spark at the plug wires. Make sure it is blue and will jump good from the wire to the block.
Weak spark {yellow} and won't jump check point gap.
Might be an internal passage plugged.
If you do find it is the carburetor a new Zenith will solve alot of problems. I have put these new Zeniths on my B's and C's and they way outperform the old original ones.
New Zenith

old · May 10, 2009

Pull the drain plug out of the bottom of the carb and make sure you have a good steady flow of gas for 5 minutes or so. Catch the gas so you can look at it to make sure you have no water or dirt in it. If you have a good steady flow there pull the main jet cap off and make sure you have a good flow of gas there. Also make sure your spark is a blue/white spark and will jump a 1/4 inch gap. Weak spark can also cause the problem you have
Hobby farm

Dick L · May 10, 2009

What is said below. Fuel flow or dirt in the power jet. A note on the idle screw. After the engine is running above an idle you can take the idle screw out and put it in your pocket. It only has to do with slow idle. If you find that adjusting the idle screw makes any change when running above an idle it is just a coincidence.

I will take some pictures of another possible problem and post them soon.

Dick L · May 10, 2009

One of the first B's or C's, I don't remember which, I bought from a fellow that had given up on. He couldn't get it to run and had let is set outside and it had rusted the pistons fast.
It had an original manifold that didn't look all that bad so I hung it up in the rafters.
This weekend I decided that I would use the intake only for a new project I dreamed up. I sawed the exhaust part off and started to clean up the rough edges and noticed a funny looking carbon spot on it and started to remove it with my angle grinder. The carbon was from the inside which I could see in an instant. I sawed it in half to get a better look at what had happened.

I just went out and took pictures so you could see what the fellow was up against and why he could not get it running.

Probly what caused all the carbon as well.

Another note worthy picture of the bolt that held the muffler that I had not remembered. It had a screwdriver slot on the outside.

Dick L · May 10, 2009

With the carbon chipped out it shows the core shift better,

The wall was thin as paper inside the exhaust part of the manifold and the only way it could have been found would have been with a vacuum or pressure check.

Jeff Z. · May 10, 2009

Good info Dick. That is a very good example of an overlooked problem.

C carb help

28sstony

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Jeff Z.

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old

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Dick L

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Dick L

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Dick L

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Jeff Z.

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