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Spark plug question

gggflyer

Active Member
Anyone know what that buildup is and what causes it. Mag on those bottom plugs and plasma on top plugs. Its hard like epoxy.
 

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It's lead covered with oil. Plug is warn out. Mag is probably weak and needs an over haul. Change the mag, plugs and harness too.
 
Mags

Without knowing the specifics, mag history and time since overhaul, as well as history plug wires, this is very bad advice. New mag?? How about an overhaul by a qualified shop IF NEEDED like most of the world does.
 
Anyone know what that buildup is and what causes it. Mag on those bottom plugs and plasma on top plugs. Its hard like epoxy.

Start with a fresh plug. And see how long it takes to fail. Check the harness, then the mag.

How long of a flight did it take to foul this plug?? Maybe a broken ring.
 
Parts

"Change" certainly implies new harness and plugs. Change the mag would imply at least a remanufactured mag. With no history from the OP except the spark plug photo this is not good advice.
My 0 320 Lycoming nitride cylinders have never used a measurable amount of oil. 2700 plus nautical miles with no measurable oil useage. The bottom plugs were slightly wet for at least 100 hours.
The OP problem may very well have started with the picture plug being shorted with carbon. The first step should be a new plug, a runup and if everything is ok a test flight. Change mag and harness is just throwing money at a problem that has not been properly identified.
In the era prior to 100LL spark plugs sometimes had to be cleaned at 50 hours.
They usually looked similar to the photo.
 
Oval center electrode, gap looks to be out of spec.
I would start with a new plug and check it again no less than 50 hours, assuming no bad mag drops or anything.
 
Anyone know what that buildup is and what causes it. Mag on those bottom plugs and plasma on top plugs. Its hard like epoxy.

Gap is WAY to big. recommend replacement. Build up is unclear, but need to confirm if that plug is even creating a spark. If not, that could account for the build up, though it could be several other things.

Larry
 
Anyone know what that buildup is and what causes it. Mag on those bottom plugs and plasma on top plugs. Its hard like epoxy.

Lead …. Bottom plugs don’t scavenge as well as top. My top plugs are always perfect in looks and wear, the bottoms horribly full of lead no matter how much I leaned on the ground. Switched to 93UL. Lean, replace the plugs that look like this one, check every oil change. And LEAN when on the ground.
 
Spark Plug

The other thing we still don't know is the manufacturer of the plug. Champion used to be the gold standard, now they seem to have a lot of problems. This could have started as a plug failure not related to lead. 0 320 with 10-1 compression, carburetor, I do not lean on ground. The carb runs lean even with the mixture full rich.
 
Don't throw money at it yet!

Before you start buying parts maybe you know someone with a cleaner/tester who would clean, gap and test. If it's good you've taken the plug out of the equation.
That is a huge gap. Maybe that's your problem.
danny
 
Thanks everyone for the replies

I cleaned and gapped and we will see how it goes. will check them in 10 hours.
 
I would find a RV maintainer friend nearby with a boroscope and do a plug and valve session. Likely need some thread chasing and best practice for whatever upper plugs/adapters to check/clean/torque and shake down the ignition harness.

A post-buy to see what you have so no surprises catch you out.
 
What about the rest

Not sure. Plane is new to me. I only had it 10 hrs then annual inspection

I agree with the comments on logbook, no way this is 10 hours, looks like the person before you ran it rich and that gap is at least 1 year or a load of flying before you bought it, it may be deceiving but I gather the gap is more than the specs call for.
My thought on this goes back to the original post from full throttle. Check the timing on the mags, clean and gap ALL the spark plugs, I would replace them all to have a clean start and check the wire harness to see that they aren’t rubbed or damaged.
If I was in your situation I would
Check oil- should be tan - not black, if it wasn’t replaced since you bought it, change oil and oil filter, check the oil screen as well.
Spark plugs/ mags next (timing, replace plugs versus gap and clean- to remove any doubt of something being missed- lead can require a pick sometimes and can be missed)
Run the engine through a run-up verify all mags are within range ( rpm or if you have a engine monitor- egts should all rise and all be about the same if one spikes more than others or decreases focus on that specifically. If it happens to be the bottom and the same cylinder the spark plug came out of. Get that resolved, otherwise I expect it will all be good for a flight.
After 10 hours if all seems fine, check that spark plug again.
That’s what I would do, but you have great feedback on other options.
Please let us know how this works out.
 
I cleaned and gapped and we will see how it goes. will check them in 10 hours.

Throw that plug away, now. The center electrode is definitely no longer round. When the major diameter/minor diameter gets to 2/1, the plug is considered worn beyond limits. This is not to be messed with. The thinner electrode will not conduct heat as well as it should, under stress it might turn into a glow plug, causing pre-ignition followed by melting your piston.
 
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