[AT] More engine issues

[john hall]

The IH dealer dad retired from kept D15Y and D21 plugs for the Farmalls. 
Whenever the plugs started fouling out we would recommend switching over to 
D21. The 2 Super A's here started fouling out plugs daily pulling tobacco 
sleds. We switched to D21's and could run 3 days--they would be skipping bad 
on the third day. We only had 3 barns so we wouldn't need them again till 
the next week. We would put in a new set before Mon. came back around. 
Eventually we overhauled the engines and it helped with the plug fouling 
issues. My point in all this is that sometimes there is nothing "wrong" with 
the plugs, the rest of the engine just might be tired.

John Hall