[Farmall] Hard starting F12

Robert L. Holtzer rholtzer at earthlink.net
Sun Feb 20 10:10:00 PST 2005


Fuel pump push rod adjustment needs to be checked also.  Apparently it 
wears substantially over the years.  My push rod had a brass build-up on 
one end.  The driving cam is pretty short throw.  Just how much push rod 
should protrude from the block at top throw I don't know.  I more/less 
eyeballed it to get the pump lever movement sufficient but not too 
excessive -- 1/4 inch or so???  Takes a bit of fiddling.  Once adjusted, 
the pump does a pretty good job.  I also put a filter in the line between 
the tank T (actually this T is a presssure regulating device) and the 
carburetor.  This keeps the "fines" out of the carb bowl and also allows 
seeing whether or not gas is present/flowing.  It tucks up under the hood 
so does not detract from external appearances.

Bob Holtzer

At 08:49 AM 2/20/2005 -0500, you wrote:
>Thanks for the info, Karl. The fellow I bought it from said he put a fuel 
>pump kit in. You can throw the gas to it & it takes it fine (no 
>hesitation). When I get back on it, I think I will start with the ignition 
>system. I'll let ya'll know what I find.
>
>Thanks,
>    Kevin
>
>>Karl Olmstead <olmstead at ridgenet.net> wrote:
>>As other knowledgable F-12 fans have noted, the F-12 is not quite as simple
>>as you'd expect. And every system has to be performing well in order for
>>the tractor to hand start.
>>
>>All you can do is go through them one at a time, systematically.
>>
>>Carburetor:
>>Pretty much the same as any other carb, except for one item. There's an
>>1/8" tube that runs from the lower portion of the carb up into the upper,
>>and it has a tiny orifice in its tip. This tube tends to stick to the upper
>>part of the carb and get broken off. I can't recall if Rice has a
>>replacement or not.
>>
>>Fuel Pump:
>>Virtually always needs rebuilding. Rice can supply a kit. Critical to the
>>starting of your tractor, since it is needed to lift the fuel up to the
>>carb.
>>
>>Magneto:
>>The impulse MUST be working, or the engine won't start. You should hear a
>>loud click or clank each time you turn the starting crank. A penetrating
>>oil will often free up the impulse, but don't use WD-40; it turns gummy over
>>time. If the engine revs freely when you bump the throttle up, the timing
>>is probably set about right. If the engine seems to 'labor', the timing is
>>retarded. The timing called out in the I&T manual is too far retarded for
>>use with modern gasoline.
>>
>>Valves:
>>0.013" gap between rocker arm and valve, same as the gap for the magneto
>>points.
>>
>>As Robert mentioned, the F-12 engine starts out with pretty low compression,
>>and you can't afford to waste any of it through leaky valves or rings.
>>
>>There's a straight slot screw in the side of the carb which gives access to
>>the venturi. On difficult to start F-12s, I squirt Wal Mart $0.79
>>carburetor cleaner in through that screw hole. Burns like gasoline, won't
>>destroy an engine like ether (starting fluid) will.
>>
>>Good luck!
>>
>>-Karl
>>
>>
>>
>> >I just bought a F12 & do not know much about them. I have a hard time
>> >starting it. It runs good once it starts. I don't know if it's me or the
>> >tractor needs a little tuning. I have heard some people say theres will
>> >start on the first few pulls, is this true? What is the best service manual
>> >for me to buy? Thanks for any help!
>> >
>> > Kevin Hood
>>
>>
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