[AT] [Farmall] Never heard such a bang

[Ben Wagner]

Here's where we are at now: I dropped my spare H4 (with a new condenser) 
which throws a nice hot spark on the tractor.  Nothing: I gave up 
cranking after nearly wearing my arm off!  So I bit the bullet and 
rebuilt the original magneto: no condenser, new points.  New distributor 
cap.  The magneto is still throwing a quarter inch spark with no 
issues.  After reinstalling it, this time I received a bang.

The timing is perfect: magneto impulse fires #1 terminal on the cap at 
exactly TDC.

I took the carburetor apart, again.  Everything is squeaky clean. This 
is a Zenith 11115B: no main jet adjustment.  The bang proves I am 
receiving fuel into the engine.

Valves are still good.  I double checked them all.  No bent pushrods, 
either.

So I'm leaning towards spark.  I'm trying to decide what would burn 
up/break while the tractor is running, which would reduce power, then 
suddenly not allow it to start at all.  I'm thinking that I should at 
least get it to run (but maybe not well) even if the coil was bad.  It 
is throwing a spark all the time while I am cranking the engine.

Any thoughts?  Thanks for helping solve this problem... I'll be glad to 
hear this creature run again!

Ben W.

www.oldpathsequipment.com
Mt. Solon, Virginia
Antique Machinery Repair and Restoration

On 2/28/2013 3:15 PM, Brian wrote:
> Sounds like moisture in the distributor cap causing a cylinder to fire at the wrong time.
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