calling spark plug gurus

[paffy]

I'm wondering what has happened here...

Normal wear and tear ?
Too lean ?
Other problem ?

There's somewhere around either 800 or 1400 flights on these babies.

Thanks,
Paul

[Tailchaser]

Those plugs look too me like the fuel mixture was right. I think that normal wear on a set of plugs with that much time on them.
From now on I wouldn't wait so long to change them out though, you were probably not getting the full performance you would have had with newer plugs.....Don't be so cheap!.....lol

Chuck

[ConRadical]

wow, 800 flights and not changing the plug??? Normal wear and tear dude.

[Kiwi]

Paffy,

Its plain old spark errosion and it comes about with old age.

Wow if you have that number of flights on those plugs that has to be close to a record.

What engine, what oil mix. Those plugs look like they came out of a fourstroke they are so clean.

You obviously have a very healthy spark as well.

Kiwi

[paffy]

It came out of a DA-150 with MTW cans turning a Mejzlik 32x10. Oil was a 100:1 Amsoil.

I think I sent this engine for leaking front bearing once and don't remember if they changed the plugs or not at that time - that's why it might be 800 or 1400 flights.

It started running a little bit funny lately, so I started investigating... new plugs are in place, we'll see tomorrow how it runs.

The plane got a new set of servos as well - need to get it top notch for the Nats .

P.

[ConRadical]

I bet those plugs will take care of your issue. That 100:1 sure is good stuff. I'm about ready to switch my new engine over.

[Toro]

take a picture of new vs old and post that up here, and look @ the gap difference. I bet your losing alot of your spark with it having to jump such a large gap

[feral63]

close the gap up and see how many more flights you can get out of them.

[DKnippen]

Gap the NGK CM-6 the thickness of a #11 Exacto blade.

[Supermod56]

Looking at those gaskets I would say you need to snug the plugs up a little more, they need to be "crushed" a little to seal right. 1400 flights, I think you got your money's worth outta those!!! Mixture looks good, that big gap is hard on the ignition, so keep em at 018-020, or use the xacto blade as DK mentioned , pretty close!!!

Tom

[Reza]

That's a record on everything to me: Plane+Engine+Spark Plugs. WOW I'm not even thinking about the 1400 number, I'm thinking about 800. What plane are these on?
If 30% of people get that much out of their planes and other stuff, I bet most companies will go out of business

[paffy]

Well, the new spark plugs made no difference

Today it started making really bad noises in the air, so I landed.

Turns out I have 2 large cracks in a prop hub. I also found one lower con-rod bearing shot and metal pieces all over the engine I'm not sure if the two problems are related, nor which one showed up first.

So much for not touching the plane before NATS.... The motor will now enjoy the unequaled pampering of the award winning DA customer service, instead of sweating its ball(bearing)s in the competition.

Spare engine is in place and looking good !

P.

[GremlinX]

Very normal for long high hours on the plugs. They look great though. Serious cracks though, ouch..

[paffy]

The crack is a minor issue compared to the engine eating the lower con-rod bearing for lunch...

It almost looks like a cooked engine AFAIK, but I'm not aware of any overheating... strange.

If I'm not mistaken, the whole crankshaft has to be replaced now, plus pretty much everything else in the motor

P.

[GremlinX]

I hear it in a lot of different brand gas motors... but I hear a lot of pinging. I can hear it bcause I was raised in 2 strokes practically... I wonder if you are not getting some pre-ignition. The spark plugs will errode, but this has me concerned.