Spark Plugs 101

wrongway john · #1 01-11-2013, 12:29 PM

Skyranch says plugs are generally already set with the gap, but a few I checked with the wire gauge show some are in a couple of thousands too far. My gap tool only allows one to squeeze in the ground electrodes. Is it okay to use needle nose pliers or vice grips to pull back on the outer edges of the ground electrodes without doing any damage to it? Other suggestions to do this?

RV10inOz · #2 01-11-2013, 04:59 PM

NO!!!

They can be pushed back, there is a tool to do it that provides no bending load on the centre electrode.

Cracking the ceramic is a sure way to guarantee a per ignition event that will kill your engine in minutes and maybe even you. No I am not joking.

Spark plugs are cheap, if you can't be sure, put it in a vice and belt the **** out of it, then throw it in the bin.

When gaping using the proper gaping tools only, sneak up on the gap fractions of a turn at a time, until you have the 0.018" wire not go through, then by rights the 0.015" should still glide through.

Hope this helps.

Tempest have some good stuff on their website. The site is hard to find though.

wrongway john · #3 01-11-2013, 07:07 PM

Quote:

Originally Posted by RV10inOz

NO!!!

They can be pushed back, there is a tool to do it that provides no bending load on the centre electrode.

What tool is that? I ordered this spark plug tool from Aircraft Spruce that is pictured here. It only pushes the ground electrodes in, not out.

Quote:

When gaping using the proper gaping tools only, sneak up on the gap fractions of a turn at a time, until you have the 0.018" wire not go through, then by rights the 0.015" should still glide through.

Hope this helps.

Tempest have some good stuff on their website. The site is hard to find though.

I presently have Champion plugs, but after some concerns raised about these plugs listed here in this thread, and this thread too, and the recommendations of Tempest, I went with the Tempest URHM40E plugs I got from Aircraft Spruce.

The package says to gap .016-.021. I can’t even get my .015 wire into most of these; they came like this. Or else I would have done it like you said, ever so gently bringing in it a small turn at a time.

If you or others know of such a tool that will bring the ground electrode out, that isn't too overly expensive, I’d appreciate someone pointing it out to me. If I can’t find one, I think I’m going to send all of these back.

Capflyer · #4 01-12-2013, 03:26 AM

How about this http://www.aircraft-tool.com/shop/de...DUCT_ID=ATS483

RV10inOz · #5 01-12-2013, 03:49 AM

That is the tool, but I am surprised you say the 0.015 wire will not pass through. Something is not right there, so double check the wire guage with a micrometer.

Maybe your gauge is wrong

Best of luck!

wrongway john · #6 01-12-2013, 11:47 AM

Quote:

Originally Posted by RV10inOz

That is the tool, but I am surprised you say the 0.015 wire will not pass through. Something is not right there, so double check the wire guage with a micrometer.

Maybe your gauge is wrong

Best of luck!

Good thinking, I should have already done so. But yeah, my wire gauge did check out close enough, my .015 shows .016 on the micrometer. Quite a few of my plugs can?t pass the .015 wire on one electrode, but does so on the other. The packaging at Aircraft Spruce was plenty good, so it wasn?t damaged or anything, but were definitely shipped out like this.

Quote:

Originally Posted by Capflyer

How about this http://www.aircraft-tool.com/shop/de...DUCT_ID=ATS483

Thanks a lot guys, once again, you save me a lot of grief. I'll order it first thing Monday morning.

RV10inOz · #7 01-12-2013, 05:53 PM

Probably find that after being run for 50 hours they would be in spec again

I should not admit this but I have had one or two over time that was a fraction past the 0.015 gauge......and i just let it go, it was a judgement call based on how far it was past. Anyway I did not keep track of it but I suspect it was still in spec next time I removed it, where others were getting to top of spec.

Glad we could help.

wrongway john · #8 01-12-2013, 07:28 PM

Yeah, since the gap always gets bigger not smaller with time, I bet you were fine. I'll probably gap closer to .016 than .021, haven?t decided yet. I don't have any wire smaller than .015, but feel like some of these are probably around .010-.012 or thereabouts. Anyway, I feel better now since you guys recommended this tool.