30 minute AC B tractor

R. Mizell · Sep 15, 2013

Any advice about a AC "B" that runs for 30-40 minutes of belly mowing then starts cutting out (surging) then dies. I replace the mag with a distributor the replaced coil (12v), points, condenser, rotor button, cap, and plug wires. Wondering if fuel problem. Removed gas cap during cut out but it didn't help. Choking helps a little but doesn't solve. At wits end.

steve(ill) · Sep 15, 2013

Are you saying the tractor was dieing after 30 minutes with the mag, then you installed the distributor and it still does it ? If that is the case, then i would look at fuel / cap vent / fuel line too close to manifold and vaporizing fuel... when it dies, pull the line off at the carburetor and check flow. If its fuel it will normally restart in 3-4 minutes. If its the coil, it will need to set an hour to cool off. A condenser will do the same thing...... Another option is the valves clearance is too small and when motor heats up, the clearance goes to zero and you loose compression. If you have gas and spark, check the valves.

Paul from MI · Sep 15, 2013

Sounds like a classic case of lack of fuel. Check the fuel flow by removing the carburetor drain plug. You should have a steady flow from the bowl for at least 2 minutes. Check for an obstruction if you don't.

dej(Jed) · Sep 16, 2013

(quoted from post at 19:29:40 09/15/13) Any advice about a AC "B" that runs for 30-40 minutes of belly mowing then starts cutting out (surging) then dies. I replace the mag with a distributor the replaced coil (12v), points, condenser, rotor button, cap, and plug wires. Wondering if fuel problem. Removed gas cap during cut out but it didn't help. Choking helps a little but doesn't solve. At wits end.

I had a B that did that years ago. It turned out to be a clogged oil filter that was pressurizing the crankcase.

Dick L · Sep 16, 2013

I have one that gets that way now and then. I take the gas line off at the carburetor and blow air back into the tank. With the fuel cap off of course. That lasts for a coupla months. Some day I gotta clean that tank. Did it a coupla weeks back. Nothing to worry about for a few more weeks I guess.

^D

Jerry Claborn · Sep 16, 2013

I have a 1949 Allis Chalmers B that did this several years ago. The manifold was leaking. After I replaced the manifold and gasket it stopped stalling out after running 30-40 minutes.

tmiller · Sep 17, 2013

with the new coil, i would say fuel as well check the elbow screen in carb, the line and clean the bowl.
--Taylor

sandman2234 · Sep 20, 2013

There are several things that could cause this, but typically it sounds like a fuel restriction problem, all but the 30 minute part. Thirty minutes is quite a long time for a fuel restriction especially if it shows up almost every-time you drive it, at about that same time frame. I think I would fill the tank completely and see if that changes the 30 minute time frame any. That will increase pressure on the fuel line and decrease the air capacity in the tank. If it changes things a little bit, start looking at fuel problems. If there is no change, then I would start looking at spark, but since you have changed the mag out, that should have eliminated that, unless you inadvertently used some part that is faulty. Capacitor next? , then on to the changing out of the coil with a known good one to verify that. Valve adjustment would be last resort, unless you have recently messed with that, then that priority goes way up.
Good luck with it,
David from jax

30 minute AC B tractor

R. Mizell

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steve(ill)

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Paul from MI

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dej(Jed)

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Dick L

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Jerry Claborn

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tmiller

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sandman2234

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