Farmall 706 running lean

Walt355

Member
I recently bought a gas 706 that had been sitting for 10 years. Filed and set the points and rebuilt the carb to get it running. Tractor runs good. I hooked it to a roller the other day and after about 15 minutes the outside of the plugs had turned chalky white and the boots were burning off them. Engine temp showed around 210. Turned the key off and it continued to run. It seemed starving for power but still ran smooth. Let it cool and it still runs good I m thinking extremely lean. I did remove the anti diesel fuel shut off needle off the valve because the coil was stuck shut from sitting. Any idea on what I can do or check. I tried it again yesterday but didn t load it as hard. Plugs still got hot but would turn off with the key. Thanks
 
Have you checked the timing?
Sometimes timing set too slow can cause heating.

Second item---what number spark plugs are in it?
Jim
 
Well first off if you cut the main jet needle then bit the bullet andf get a new one . Next make sure all passaages in the carb are clean and open , make sure the float is set correctly , next make sure all the manifold bolts are tight and no leaks there. Next check the heat riser and make sure the coil spring is in place correctly . No on to timing check . Depending on what engine you have and this is important you have to know if you have the C263 or the C291 as not all 706's time the same . A C263 sets at 23 Degrees BTDC at rated RPM or in other words wide open . The C291 sets at 18 Degrees at BTDC at rated RPM Spark plugs i prefer to run in them are the 386 Autolites or the C 86 A C's . DO NOT RUN REG GAS , yea i will catch flack on this but 93 octane is what is needed and good luck finding it . Also you only use LOW ASH 30 weight OIL in them . All i can say is good luck as we have stopped usen 706 gassers due to fuel related problems . As soon as it stops raining i have to go look at a 806 gasser that was freshly rebuilt by someone else and it to has seized up .
 
Because it was not mentioned I would like to add that the fuel system may be blocked and not
delivering enough fuel. After setting 10 years in a tank gas gets pretty crappy so make sure that is
okay, as in sediment bowl and screen is clean and no crud in the tank. I think the criteria is fuel
delivery at the carb should be at least a pint every 3 minutes. Even though in general poor fuel
delivery will cause an engine to run uneven or stall it could be that it is supplying just enough to
keep it running but just running lean. Your descriptions do tend to lead to a lean air to fuel mix
caused by a carb issue. Not to belittle your mechanical knowledge, but I assume you are aware of
the screen in the inlet fitting of the carb. Anyone who rebuilds a carb properly would pull it out and
know it is there.
 

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