n3qm

New User
Any ideas on why a complete repair 1982 massey 230 gas will foul the #4 plug within 1 hr running....blacken, smokes, power loss. It has an igniter and match coil. Complete engine rebuild, wires,ignition,carb, etc. It was all done, but can't get rid of this gremlin! Prior to all, every 3-4 years new plugs solved the problem All the local experts have failed on this. Any one have an idea. Thanks

Bill
 
What does the fouled plug look like?

Is it clean but wet with gas if pulled immediately after running? White vapor smoke, eye burning, raw gas smell.

That can indicate weak or no spark, low compression.


Is it flat black soot? And the smoke, black smoke?

If so, those are indications of too rich.

Has the air filter been serviced and checked for restriction, mouse nest, mud dobbers, etc? Will it run better disconnected?

Any flooding, will the carb adjust? Choke fully open?


Or does the plug fouling have a glossy black, or black crusty appearance, the electrode bridged with carbon?

That indicates oil burning. Could be rings were damaged on install, problem with the bore, cylinder wall, ring land damaged or broken. Sometimes rings will be slow to seat, but that is usually not severe enough to foul plugs. Blue smoke under load indicates rings, on start up indicates valve guides.

A compression test might give a clue, also excess puffing out the crank case breather tube indicates blow-by, leaking rings.
Plug Chart
 
Thanks for your respond. I'm working on as time permits. Assuming I've done all correct with the rebuild and all components, I've noticed a small leak on the manifold over the #4 cylinder. (on the '"ear" tab where it bolts on) Is it possible on the exhaust to affect the intake in any way? Logic would dictate that only #4 being the problem eliminates a lot of carb,etc and other components since it is fine on the other cylinders.

Bill
 

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