Yet another Spark Plug Question

[jimbo]

Couldn't find an answer after a quick search so here it goes.....

I have Champion #REM-38S fine wire iridium plugs fired by a Left side Mag and a PMag on the right side. The gap on these plugs are 0.016. I would like to increase the gap fired by the PMag to take advantage of the greater energy coming out of the PMag. Champion says the gap range on for this plug is 0.016-0.021.

Question: is it OK to increase the gap to say 0.032 without faulting or harming the proper operation of the plug?

and...Can the gap be increased without breaking off the wire? If so, how?

I know, I can always go with auto-plugs but it seems like I would be taking a step back in quality....and that is another thread entirely.

Thanks,
Jim
RV9A
Phase 1

[rzbill]

I was just recently reading a document about large gapping fine wire plugs. I think it was possibly the PMag manual.

It specifically warned about being careful with the fine wire plugs because they can break where the wire is welded to the plug body.

I just read it. I have no direct experience.

[RV10inOz]

DO NOT try to do it.

The plug ceramic core is a serious part of the plug and if cracked during the process, its function will be compromised and a preignition source is created. That is bad, especially if you do not know it at the time or how to handle it.

Besides, the Champion plugs will most likely have high resistance values in 300 hours and be junked.

[jimbo]

I have heard people have done it (increased gap from 0.016 to 0.32 on an aviation iridium plug) but have not heard to what success and if it can effect the operation of the plug negatively (other than the obvious damage in the process).

Anyone else care to chime in with first hand experience?

Jim

[Neal@F14]

The good old fashioned UREM37BY massive electrode spark plugs can have the gap easily set to pretty much whatever you want.

[Arlen]

Originally Posted by RV10inOz

Besides, the Champion plugs will most likely have high resistance values in 300 hours and be junked.

Get Tempest?

[GLPalinkas]

Originally Posted by RV10inOz

......

Besides, the Champion plugs will most likely have high resistance values in 300 hours and be junked.

I just did a condition inspection (240 hrs) and dang if you weren't right on David. I read in a previous thread (Dan Horton, IIRC) that Champions internal resistance increases around 300 hours. Two of my Champion REM38's were over 5000 ohms. I replaced them all with Tempest UREM38E's. Noticeable difference. Runs smoother, no missing....

[RV10inOz]

Yet they bury their head in the sand saying that you need to use a high voltage to test them not a multimeter.... :roll eyes: And we are all silly.

My response is....you can see on the EMS and feel in your butt a difference. Even if the low voltage multimeter is not sufficient, whey then the measurable change anyway.

The guys who make TASERS that the cops use know how to make high voltages, and when one of the directors / senior engineers found this problem in his Beech Baron he took them into his lab for some high voltage testing. The results support theory that they go off over time, and not the OEM's head in the sand position.

It would logically make sense that the coil in your magneto will appreciate less stress too.

I tested 6 fine wire C brand yesterday with maybe 150 hours on them. One was around 1500 ohms, the rest already at 3300-3700.

[psalter]

Originally Posted by GLPalinkas

I just did a condition inspection (240 hrs) and dang if you weren't right on David. I read in a previous thread (Dan Horton, IIRC) that Champions internal resistance increases around 300 hours. Two of my Champion REM38's were over 5000 ohms. I replaced them all with Tempest UREM38E's. Noticeable difference. Runs smoother, no missing....

My story reads about the same with old Champions. I had a Christen Eagle with a pumped up IO-360A1A that would demand a runup and aggressive leaning to clear the plugs prior to flight. Even with aggressive leaning I had issues with the plugs fouling. I talked with Tempest and decided to change brands. After pulling the Champions, I tested them on the Tempest tester (easier than an Ohm meter) and found I had one plug that tested........good! The rest tested over 5000 ohms, therefore, bad.

Since changing to Tempest plugs the engine doesn't require aggressive leaning to clear the plugs prior to take off and the idle is much smoother. The old Champions all tested good in my ancient Champion pressure type tester, which I will put on Ebay ASAP.

Funny thing, I decided to test old spark plugs pulled out of my Yak's M14P radial and found the Russian plugs tested better than the Champions.

My opinions only, your mileage may vary. I am sold on Tempest and will put them in my RV4 (I took delivery yesterday) when the time comes.

Phil