jubilee carb choise

ericlb · Mar 15, 2010

im looking at buying a new carb for my old jubilee, ive rebuilt the original 3 or 4 times in the 12 years ive had the tractor and once for the previuous owner, this thing smokes [ unburnt fuel] worse than my kenworth on a cold morning,lately it loads up, fouls plugs and just runs like crap, ive tried readjustine the main jet and the fuel mixture no dice, so something must be wrong with the castings or something, in the tractor parts here, i have 2 choises one looks like the original, the other is a zenith which is supposed to replace the original, have any or you used one of these and which is the better choise between the 2?

Jerry/MT · Mar 15, 2010

Are you sure the problem is the carb? A weak spark can cause poor running, requiring fuel enrichment to get the engine to run. (the spark should be FAT AND BLUISH-WHITE, the color of lightning.) The cleanest carb in the world will have problems with a weak spark.

Air leaks around the carb metering section can cause excessive leaning. The usual culprits are the throttle shaft seals or wear of the throttle shaft, leaing around the intake manifold connect flange /carb interface, the manifold itself (rust spots or cracks), and the manifold gasket.
Finally, the key to a good carb rebuild is to get the carb really clean and that can mean soaking it in real carb celeaner from 24 to 48 hours to get all the passages really cleaned out.

I presume you hve a Marvel-Schebler OEM carb on the tractor. They are about as simple and rugged as a carb can be and are rlatively easy to rebuild, but you gotta" get them really clean in the process. there"s a guy on the N forum (GBin MT) that rebuilds them and you might holler for him andask him about rebuiling them.

old · Mar 15, 2010

As Jerry says weak spark, timing off low compression and one thing that get forgot about and almost never serviced it the air cleaner and it does at times need to be removed and soaked to clean the screen in it. The old M/S/ carbs are very simple and almost bullet proof

Anonymous-0 · Mar 15, 2010

I will be more than happy to buy your junk carb. Unless someone has everything stripped that is. Nothing is imposible, but I will certianly gamble on the carb being rebuildable.

ericlb · Mar 15, 2010

thanks, ill see if gb has any tips over on the n forum, this tractor is a using tractor on my farm it runs nearly every day, ive done a complete tune up on it again as i thought it was spark too, but it has bright good spark, new plugs pionts condensor, rotor cap and wires everything is clean bright and tight, its black smoke out the pipe,which is unburnt fuel tractor doesnt use any oil between changes, either im missing something or i got a unusual problem

Jerry/MT · Mar 15, 2010

I doubt you have an unusual problem. Most of these old machines IF they are in reasonable mechanical condition(good compression, good valves properly adjusted)usually have fuel system or ignition problems. Because of wear issues due to the old age of these tractors, they"re not always easy to figure out. By all means, holler for GB. He can give you some good carb insight.
Persistance will help you find the cause. Just don"t assume any thing about the ignition of fuel system. Systematically check it out and you"ll find the problem.
Are you plugs all sooty? If you"re blowing black smoke and have sooty plugs, that"s a good indicator of mixture problems, How many turns out on the power jet screw? Have you checked the basic timing and the advance function on the ignition system? Hows the bushing on the distributor? Excessive bushing wear will make an engine run like a three-legged dog!

jubilee carb choise

ericlb

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Jerry/MT

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old

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Anonymous-0

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ericlb

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Jerry/MT

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