Farmall 350 has black spark plugs

Anonymous-0 · May 20, 2009

Wondering what can cause black plugs. I can wire brush them and it runs better. It does smoke at start up and has some blue smoke. It otherwise sounds good and runs OK. Hoping I can address the rich condition without going in too deep.
I have tried adjusting the jets but have not had much luck.

Ne super H · May 20, 2009

Try putting a hotter plug in.

Andy Martin · May 21, 2009

Is a 350 like an M carburetor where the idle mixture is air: screw out for lean and in for rich? A good carburetor cleaning may be in order. I don't usually put kits in carburetors, just take them completely apart and clean every passage really well. It will make a difference.

mkirsch · May 21, 2009

Your spark plugs are getting fouled. Whether it's oil fouling or fuel fouling, depends on the black. Is it wet and gooey black or dry and powdery black?

Wet and gooey black is oil. The only fix for that kind of fouling is a rebuild of the engine. Since you're getting blue smoke, my bet is on oil fouling.

With fuel fouled plugs, maybe some carburetor adjustments are in order, maybe a rebuild.

Anonymous-0 · May 21, 2009

The plugs have a dry or sooty black to them. The tractor has points ignition with a 12 volt conversion and I wonder what would be a good hotter plug to try.
I bet the carb does need a good cleaning, I must confess it looks tricky with how the carb is connected.
And shoot! I thought turning the idle in would make it more lean.

Bob M · May 21, 2009

The blue in the exhaust is from burning oil. While a properly set carburetor will help keep the plugs from sooting up, the only permanent solution is to find/correct the cause of the oil burning.

Depending on how badly the engine is burning oil Champion D21 or D23 plugs (or another other mfr’s heat range equivalent…) may be hot enough to keep them from fouling.

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Incidentally you can do a quick “field rebuild” on the carburetor without taking it off the engine. Simply disconnect the air cleaner hose and choke rod, then remove the 4 screws holding the throttle body to the bowl assembly and drop the bowl.

Frequently it’s only the bowl that accumulates junk/needs cleaning. Unless the throttle body is plugged up really bad it can be cleaned simply by taking out the idle mixture screw and blowing the passage out with compressed air.

GordoSD · May 21, 2009

Have you changed the load adjustment? That idle screw only affects the mixture at idle. Are you gettin some black or brownish smoke when you pull the throttle open?
If you can't lean it out with the load screw then you will have to lower thr float setting. That is adjust so that the valve closes "sooner
(lower fuel level in bowl).

Gordo

Brownie 450 · May 21, 2009

Have you checked the air cleaner for dirt build-up in the cup? If not, look for any other restriction in the air intake system.

Red Mist · May 21, 2009

(quoted from post at 09:20:16 05/21/09) Have you changed the load adjustment? That idle screw only affects the mixture at idle. Are you gettin some black or brownish smoke when you pull the throttle open?
If you can't lean it out with the load screw then you will have to lower thr float setting. That is adjust so that the valve closes "sooner
(lower fuel level in bowl).

Gordo

I agree with Gordo; well worth trying.
mike

Farmall 350 has black spark plugs

Anonymous-0

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Ne super H

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Andy Martin

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mkirsch

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Anonymous-0

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Bob M

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GordoSD

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Brownie 450

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Red Mist

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