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High Resistance in Tempest spark plugs

vic syracuse

Well Known Member
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There's been lots of talk in the last few years about high resistance in Champion spark plugs. I have seen many of those failures and started using only Tempest plugs many years ago. Recently I had a customer who could not hot start his RV-8 (fuel injection), and the problem jsut recently began. Less than 2 months ago I had replaced the upper plugs with BR8EIX and the lower plugs with Tempest UREM40E's, only because they were all worn. It was in for the CI this week and in the process of reinstalling the plugs after a compression check I always check the resistance, even though these plugs were only 2 mos old and had only 35 hours on them. Three of them showed INFINITE resistance, checked with 2 different meters. I replaced all of them and am in contact with Tempest, who now has the plugs, and has promised to check them and get back to me.

I have another friend who was having a hard time hot-starting his Stearman. He bought 12 brand new UREM37BY Tempest plugs and one of them right out of the box showed INFINITE resistance.

So, for those of you having a hard time hot-starting, do check those plugs. Trust but verify. :)

Let's not start a thread on Tempest plugs having a problem until we get more data.

I performed over 12 hot starts after replacing the plugs, with no problems.

Vic
 
I just replaced 8 Unison Autolites with Tempests because I was experiencing hard hot starts on an O320. One of the old plugs showed infinite resistance through the center electrode but would show acceptable resistance to the side electrode (internal short?).
The following weekend that same, now cold, Autolite plug checked good. So far so good with the Tempests.

Hint : Take a little emory cloth to the end of the electrode before checking the plug's resistance.
 
I just replaced 8 Unison Autolites with Tempests because I was experiencing hard hot starts on an O320. One of the old plugs showed infinite resistance through the center electrode but would show acceptable resistance to the side electrode (internal short?).
The following weekend that same, now cold, Autolite plug checked good. So far so good with the Tempests.

Hint : Take a little emory cloth to the end of the electrode before checking the plug's resistance.

I have also found that electrodes with carbon build up will have a definite effect on resistance readings,,even digging with the point of the probe. A always run mine through the blaster and have them ready to install before I test them with the meter now. FWIW, I just replaced all 12 of my plugs with Tempest plugs in my IO-540 and tested them prior to installation. The readings new ranged from 1189 to 1876. I plan on keeping track on each individual plug as time progresses.
 
Vic,

I had a similar issue with a 150 hour Tempest plug as you did. I was getting a slight miss in flight. First thing I did was clean and check the plugs. One had an infinite resistance. I also got in contact with Tempest and was asked to send the plug in. The tech at Tempest also cleaned the plug and checked the resistance and got a similar result. Upon further inspection he noticed some "crud" inside the barrel where the spring makes contact. He cleaned it with some solvent and Scotchbrite and re-checked the resistance. It measured as it should, about 1100 ohms. We don't know how crud could have gotten in there. He put it in one of those sealed plastic tubes and mailed it back to me. It's been flawless since.

Jerry Esquenazi
RV-8 N84JE
Flying since 2007

There's been lots of talk in the last few years about high resistance in Champion spark plugs. I have seen many of those failures and started using only Tempest plugs many years ago. Recently I had a customer who could not hot start his RV-8 (fuel injection), and the problem jsut recently began. Less than 2 months ago I had replaced the upper plugs with BR8EIX and the lower plugs with Tempest UREM40E's, only because they were all worn. It was in for the CI this week and in the process of reinstalling the plugs after a compression check I always check the resistance, even though these plugs were only 2 mos old and had only 35 hours on them. Three of them showed INFINITE resistance, checked with 2 different meters. I replaced all of them and am in contact with Tempest, who now has the plugs, and has promised to check them and get back to me.

I have another friend who was having a hard time hot-starting his Stearman. He bought 12 brand new UREM37BY Tempest plugs and one of them right out of the box showed INFINITE resistance.

So, for those of you having a hard time hot-starting, do check those plugs. Trust but verify. :)

Let's not start a thread on Tempest plugs having a problem until we get more data.

I performed over 12 hot starts after replacing the plugs, with no problems.

Vic
 
Tempest spark plugs

Yesterday was unable to start our IO-320 powered RV6, it has been increasingly difficult to start over the last few hours. The Tempest fine wire spark plugs had been installed two years and 110 flying hours ago. Today have replaced them with the original, cleaned up and gapped, Champion massive electrode plugs and all is back to normal, have not yet checked the resistance of the removed plugs but have sent a message off to Tempest. Am aware of similar issues on our airfield with these plugs, will report back what comes from Tempest themselves.
 
Tempest fine wire spark plugs

Further to my last post about these plugs, have been in contact with Tempest who have asked for them to be sent back (all 8 ) 6 of which showed infinite resistance, they say they are going to send us another set, will report back further when they arrive.
 
Had one too...

I just had an open on a tempest too. Champion had the worst problem for this
in my opinion. Also, I can't take the plug apart like the "tech" did.
I do like Tempest so lets see if this gets resolved..
John
 
I think you will find that Tempest will do a good job for you in root causing the issue and reporting back. They have a very good reputation for this.
It is not unusual for resistance issues to pop up from time to time on any plug. It is critical that the plug be properly cleaned BEFORE doing the resistance check. This "Sparkplug Cleaning the Right Way" pdf is a very good guide by them. IF your doing your own plugs, you should have this handy.
The emory cloth suggestion to the fire end is a very good suggestion just prior to resistance checking, along with cleaning the terminal.

Here is a useful piece of information on resistance numbers for Tempest

ResistanceMaintenanceCard.png


If you ever have concerns about your Tempest plug our how your testing it, shoot Vince Bechtel from Tempest and email. He is very responsive and a great guy to work with. [email protected]. I like to get things straight from the horses mouth. They know their stuff. Also you will find a lot of information on their website.
Good luck on your root cause and report back.
 
Tempest Contact Info

Hello Everyone,

My name is Vince Bechtel and I'm the Director of Sales and Marketing for Tempest.

First, let me say thank you to Mike Stewart for the kind words about myself and Tempest. We strive to manufacture the highest quality products in the industry, but during those times we don't meet our customers expectations I want to make sure we make up for it with our customer service.

Regarding resistance issues specifically, your best bet for getting an accurate reading is to make sure the firing end and the terminal well are cleaned prior to using an AT5K or ohm meter. Once both ends are cleaned the leads must touch the center electrode and terminal well contact to get a proper reading. Mike attached a resistance card on his prior post.

I have read through the forum chain and want to personally make myself available to anyone on the forum. I will try to check the page regularly, but it is best to contact me using the contact information below. If anyone has future questions or concerns don't hesitate to contact me directly.

Thank you all for your support of Tempest.


Vince Bechtel
[email protected]
(843) 991-1199
 
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