4.3 spark plug what could this mean?

[MRS]

Last time out trolling and boat would not ideal so came home pulled plugs and found this.:mad-new:

 

[Bondo]

Re: 4.3 spark plug what could this mean?

Ayuh,... It looks abit Black, could be runnin' to rich at idle,....

 

[MRS]

Re: 4.3 spark plug what could this mean?

Ya ate the center of the plug out where do I start? put new plugs in and going to change points and condenser plus check timing and duel motor just will not ideal right when I try to troll slow? Timing also..

 

[Bondo]

Re: 4.3 spark plug what could this mean?

Ya ate the center of the plug out where do I start? put new plugs in and going to change points and condenser plus check timing and duel motor just will not ideal right when I try to troll slow? Timing also..

Ayuh,..... Sounds like a full blown Tune Up is in order,....

If the electrode is eroded, which I can't see, it could be runnin' lean at higher rpms, detonatin' the plug tip, 'n overly rich idlin' could be causin' the soot,...

Start with yer Tune Up, 'n look into the Carb if ya think it still ain't Right,...

To really "Read" the spark plugs, ya gotta go run it hard, 'n shut-down rather quickly, 'n check the plug color for top end,....
Low end is idlin' anyways, so burnt plug tips can soot up goin' to the dock,...

 

[coolbri70]

Re: 4.3 spark plug what could this mean?

looks like it could be detonation, either from low grade fuel or lugging the engine, but I cant tell from the pic as its not 3d. but from you describe as eaten away

 

[MRS]

Re: 4.3 spark plug what could this mean?

Thanks will tune up and check back in with results..

 

[4now04]

Re: 4.3 spark plug what could this mean?

Do the tune up, but pay attention to what these removed engine parts, and other parts you re-use, look like. What do the other plugs look like? Are the center electrodes also significantly worn or gone? With this center electrode worn that much or gone, that cylinder was probably not firing. That would explain why you have the soot on the plug. If all plugs are about the same age, you may have had a center electrode come out of the plug. If so, hopefully it did not bounce around too much in the cylinder and damage things before it went out the exhaust port. I would try to look inside this cylinder to see if the piston, cylinder walls, and head are damaged or look OK. if the electrode is lodged in the piston or head it may eventually come loose and cause damage. If you can not find it, I would tune it up and put it back together. Go run it a few times. Pull this plug again to see how it looks. I would be cautious about any long boat trips to remote locations for the first few trips.

 

[Lou C]

Re: 4.3 spark plug what could this mean?

The last poster made some good points, after you replace the plugs and warm the engine up I might want to do a compression test just to make sure there is no damage to that cylinder. I would also want to make sure that the fuel mixture us set right and that the total timing advance is right also. Too lean a fuel mix and/or too much timing advance will burn up plugs.

 

[bruceb58]

Re: 4.3 spark plug what could this mean?

Too see if the mixture is correct(not idle speed) you almost have to run at high speed for awhile, immediately stop your boat and then do a plug read. You could easily have a lean condition at high speed and a rich at idle. When I use to re-jet motorcycle carbs, this is what I would do.

Definitely do what Lou said and check your spark advance.

 

[jerryjerry05]

Re: 4.3 spark plug what could this mean?

Has anyone set the idle back so you can troll?
The motor needs to run at a certain speed for it to operate right.
Do a comp test.
What's the RPM's set at?
Timing?
Dwell?