Arcing on plugs

I've had a couple of spark plugs arc or track down the outside of the porcelain lately causing the cylinder to die, looking for any input on the cause, done all the usual things plugs clean when installed, cleaned plug tools, inside of leads etc. using MSD 44 NGK R6061-10 Plugs. Any help appreciated
Thanks...

 

Plug gap? ?

 

arcing

my experience with arcing on the outside of the plug has been wires having too much resistance or a weak ignition output
frank

 

Plug gap is 15 thou
Thanks

 

Try looking on the inside of the spark plug boot. If there is any oil residule there, this will cause the arcing that you are seeing

 

Bad grounds. Cylinder head to cylinder head to coil is a must with a 44.

 

BTW, once you arc or carbon track a plug the boot should be changed.

 

Good point !

 

what spark wire you using?

 

I've had the same problem, it was the rubber boots. MSD wires.T.Howell is right on the money!
Mike Etter/Nerves of Steel A/FC

 

I have had problems with some of the NGK plugs cracking and shorting. I opened up the holes in the spark plug tubes and it hasn't done it again. It killed several good runs by droppping cylinders. We put new plugs in on every run and the brand new plugs would cracked the porcelain and short out.

 

Thanks guys figured it was probably the wires (MSD wires) we will fit a new set and see what happens, we dont do many runs out here and its not good to waste them... Thanks again rolme.

 

Something to keep in mind is to check the resistance of the wires figured in ohms per foot which varys depending on whose wire you're using. Check it even on the new wires you make up. Also, be sure and replace the wire from the coil to the cap often( at least every couple races) as it does 8 times as much work as the other wires. Between brakekleen and 44 amp mags, these wires have a tough life. Just my $.02

 

good point Will. Simple idea but somehow I never thought of it. Must have been all those paint chips I ate as a child. Dave Germain

 

Good idea, we warm up on old plugs but after replacing with new "test fire" the new ones for 10-15 secs.

 

Your best bet is to get rid of the resistor plug.

 

We've seen this with NGK's also.
I'm not convinced it's a lead problem. A high resistance or faulty lead will result in less voltage at the plug, so it shouldn't aggravate a problem at the plug.
Also, I believe it happens when the spark is trying to fire under the cylinder pressures seen during the run, so I don't know that doing a start up on the run plugs would cause the plug to misfire at idle and show the fault before the pass.
Just my thoughts...

 

Ran a boat for awhile had lots of moisture to deal with.
We used Mac's silicone spray part # 8300 at your Napa parts store.
Spray the inside of the plug boot when new or after cleaning them and every time the wires came off and no more problem.
It is very important to keep the boots clean to prevent arcing.
We just squirt a shot of alcohol from the primer bottle to rinse them out when needed (dries fast) then spray again with Mac's and ready to go.
Also keeps the boots from sticking that can cause damage during removal that causes crevices for crud or air to get into that makes a pathway for current. Once stretched or twisted boots are junk.
Mac's also can be used as a gasket treatment to keep gaskets from sticking. And on O rings and hoses for ease of assembly. Dries with no residue. Not for use with O2 sensors in some areas.