[Farmall] Hard starting F12

[Karl Olmstead]

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