I have a 1940 hand start JD H tractor. I took it for a long ride mainly to get it up to temperature (180 degrees) and brought it home where I unfortunately stalled it. I could not restart it other than to pull it. Is there such a thing as vapor lock on an old tractor like that? The last couple days it started right up on a cold start.
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- Thread starter Dwashebek
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buickanddeere
Well-known Member
(quoted from post at 20:19:36 06/26/18) I have a 1940 hand start JD H tractor. I took it for a long ride mainly to get it up to temperature (180 degrees) and brought it home where I unfortunately stalled it. I could not restart it other than to pull it. Is there such a thing as vapor lock on an old tractor like that? The last couple days it started right up on a cold start.
Check the valve lash, could be too tight .
Common problem on a hand start tractor and the brand does not matter. My 1935 JD-B has always been that way and may grand father talked about it being hard to start when hot. My grand father got it in 1940 and It has always been hard to start when hot. Intake manifold is hot so the gas vapors seem to steam off and not get into the cylinder as it should when cold
The mag can nee your trouble,,if the impulse spring is weak or broken they will not start with hand cranking,,but will start up when pull started,, and I think the "B" model mag is better than the "C" model,,the "C" model is the one with the short coil wire on the cap..if you don't hear the mag clicking as you crank it the impulse spring is broken..
Resting Relics 1
Member
Hey,
Gotta agree with "Old" on this. Common problem with these older hand start tractors. I agree in the thinking that the gas is evaporated in the manifold before getting into the cylinder correctly enough to restart. Good Luck!
John
Gotta agree with "Old" on this. Common problem with these older hand start tractors. I agree in the thinking that the gas is evaporated in the manifold before getting into the cylinder correctly enough to restart. Good Luck!
John
buickanddeere
Well-known Member
Does liquid gasoline burn or vapour gasoline ?
Where does this evaporated away gasoline disappear to from inside the manifold ? Has to ether enter the combustion chamber or blow back through the carb .
IMHO, a hot manifold should help the starting, the carburetor and fuel going to it must be kept cool to prevent boiling in those components. Since it has been 30 years since cars had carburetors, most might have forgotten the hot soak start issues, this was NOT caused by evaporation in the manifold, but was caused by boiling in the carburetor sitting on the hot manifold. It is easy to test the valve issue by doing a hot/cold compression test, if hot is significantly less, if not then this is not the issue.
The tractor is a hand start so I?m not sure how to answer your question about it cranking fast when hot. The magneto was just rebuilt and produces a strong blue spark. Thank you for any advice you can think of. I?m thinking that vapor lock was/is the problem. I don?t run the temperature up to 180 very often, so I?ve not experienced this before. It has started perfectly since, but always cold.
Hard starting when hot is a classic case of a weak or bad coil in the mag. If the mag is a WICO X I would replace the coil with a HOT Coil 5-5029. The spark will be approximately twice what a regular coil produces and makes hand crank tractors start easier. I would also change the condenser to a NAPA ECH W1200. The original condenser does not handle the additional charge as well as this condenser. Call me if you want, I rebuild magnetos as a side line.
Bruce 864-933-5073
Bruce 864-933-5073
Thanks Bruce. The mag is a type C and was just rebuilt. It produces a strong blue spark, so I don ?t think that the mag is the problem. I like the thought that it may have just vapor locked after I ran the temperature up to 180-190 degrees. I purposely did that to get the tractor to an operating temperature. I have never done that before and never experienced hard starting before. Thanks for your help.
The WICO C condenser is unique in the fact the condenser also holds the contact points. I do not know of an option for the condenser on a WICO C. Check the spark with the engine warm. The magneto (coil) can check good when cold and break down once the tractor comes to operating temp. The tractor will continue to run. However, once stopped the impulse is the only method of creating a charge to the coil. The reason the tractor will start when pulled. The mag is spinning fast enough to create an adequate spark.
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