Allis Chalmers "B" - HELP!

I have a 1947 Allis Chalmers "B" that has sit in the barn for about 4 years. I started 'fixing it up' a few months ago mechanically (cosmetically it is brilliant) and have came to a halt over this infernal matter.

I replaced the points, plugs, rotary button, coil, sediment bowl gasket, changed the motor oil and filter, changed the breather oil and thoroughly cleaned the associated breather filter screen. I flushed the gas tank and put clean non-ethanol gasoline in it, so everything is running clear. I took off the carburetor and had it totally rebuilt and replaced it.

My issue is that it will immediately start up, however it only runs for about 5 to 10 seconds and then it shuts off. Have have adjusted the carburetor (from a trickle to a full flow) and no effect is noticed one way or the other. The tractor still starts and runs for 5 to 10 seconds and promptly shuts off.

Any advice or assistance anyone could give me would be greatly appreciated.

Regards,

Dwayne Hubbard
(770) 683-2900

It was running several years ago. It was my fathers tractor and he passed away in 2014. The tractor hasn't really been run since about 2012.

It may be around the manifold that is leaking. I had not considered that. The carburetor was rebuilt because I thought it was that which was leaking. However, since the rebuilt one was put on it still streams gasoline somewhat if the flow is strong and steadily set.

The carburetor was taken off and professionally rebuilt.

These vintage tractors with manual choke and updraft carburetor always require full choke for initial starting and then the choke generally needs to be opened within seconds of its initial firing or it will be flooded and will die.

You can tell that by pulling a plug and finding it awash in gasoline.

Otherwise you need to determine if its running out of fuel or losing ignition. Either can kill it in a few seconds. A series timing light could show spark. A plugged screen on the fuel inlet adapter to the carburetor or varnish in the fuel line and/or the sediment filter can limit fuel flow.

Usually an overheating coil runs more than ten minutes before failing, or a condenser can last that long. Most often a condenser doesn't recover from overheating but a coil often does.

Check for spark by taking a plug wire off a plug and hold the bare end of the wire about 3/8" inch from the block and crank the engine. There should be a blue spark that long in air if the ignition is good. Or that could be the wire from the coil to the distributor providing its battery ignition.

Gerald J.

"Professionally " rebuilt don't mean anything!!!----IF you put on a NEW never used carb, things could be different!----And a side note,---- WERE in H--- do you get NON-ETHANOL gas from????? ,----around here there is no such thing!!!! LOL!!!!

Also you might take the needle and seat out and check for free movement, AND make sure the float is set to proper specs.----don't trust "pro.",---check for yourself!!! LOL!!!! thanks; ac fleet

From experience be sure the venturi in carburetor is not installed upside down. 

Rebuilding a carb and not putting in a inline filter is a waste of money on an old tractor as
the carb will just fill up with whatever stopped the carb up in the first place.And yes gas will
pass thru an inline filter with gravity flow as I have them on every gas tractor I own and
have 2 on the tractors with fuel pumps like the D19.

When I was very young I remember my father dissembling the B Carb on a sheet of newspaper so he could well see the parts.  He used a very fine wire at the bottom of the carb to clean the bottom jets.  Seemed - as mentioned above - a very normal problem: even in the 40's.