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MADJAK
05-30-2001 12:55:13
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Many thanks to all for your suggestions, however, (unfortunately) none of them seemed to have any impact on eliminating the problem. To recap, I have a recently acquired 1952 8N that produces black exhaust smoke and rich fuel smell at any throttle setting below approximately ½…it still smells rich at full throttle, but you don’t notice the smoke very much. I purchased and installed a brand new carb, which didn’t help at all, in fact the tractor behaves just as it did with the old carb (adjusting the idle air and fuel mixture screws in or out on either carb seem to have little effect). Per your suggestions, I’ve completed a tune-up with new plugs, points, (set to I&T FO4 specs) rotor, condenser, and distributor cap, and completely cleaned out the air cleaner (it wasn’t dirty at all, the oil bath was very clean). Still no improvement. I next began to suspect the 12-volt conversion and some problem related to that modification and the coil. I have the side-mount distributor and automotive type coil, along with the standard ballast resistor, and seem to get a nice blue spark at the plugs if I pull the plug wires off one at a time with the engine running.
I’m still puzzled by the fact that the engine seems to smooth right out, stop smoking, and actually idle faster if I turn off the after-market in-line fuel shut-off valve near the carb (until it runs out of gas), which makes no sense to me at all. That behavior would indicate that the fuel pressure is overriding the fuel needle and seat in the carb, overfilling the carb fuel bowl and causing the rich condition, but how can that be with a gravity feed fuel system?? Aren’t all N tractors gravity fed their fuel? Is there some sort of fuel volume limiting device in the original fuel line and/or valve that is missing on my tractor, and that could be the source of the problem? I did note that the fuel valve mounted on the gas tank seems to have been modified somewhat (there is no shut-off knob on it, and it has what looks like a second line coming out of it that has been cut off and crimped closed, along with a fuel line that runs between the top of the engine and bottom of the fuel tank, then takes a 90 degree turn downward to connect to a piece of rubber fuel hose, fuel filter, another piece of fuel hose, plastic fuel cut-off valve, and another piece of hose to connect to the metal fuel inlet tubing on the carb).
I’m really baffled by this problem, and I know this is a long-winded post, but I wanted to provide as much information as possible to see if any of you N experts out there have ever had this problem, and how you corrected it.
Sincere appreciation in advance for any help you can offer.
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