Tempest

[jmvolpp]

I took the recent AOPA spark plug article to heart and finally got around to checking the resistance of the Champion REM40E plugs (328TT) in N44305's A65-8 and found only one in compliance at 1500 ohms. The other 7 were off scale high, so I replaced all with Tempest UREM40Es and, since enough water had drained away from Friday's deluge, was able to flight test this morning. Gone is the low rpm lope that had folks asking if the engine was sporting a full race cam - overall smooth operation is quite a noticeable change.

On another note, I plan to attend OSH next month and hope to put some faces with the names I've become familiar with through the forum.

Mike V.

[astjp2]

Re: Tempest

5k ohms used, 1.5k new...if its a used plug they can have higher resistance....I have tested a bunch that were 2.3k ohm, that is still a good plug. Above 5k ohms causes the mags to overheat and the coils to break down. Tim

I took the recent AOPA spark plug article to heart and finally got around to checking the resistance of the Champion REM40E plugs (328TT) in N44305's A65-8 and found only one in compliance at 1500 ohms. The other 7 were off scale high, so I replaced all with Tempest UREM40Es and, since enough water had drained away from Friday's deluge, was able to flight test this morning. Gone is the low rpm lope that had folks asking if the engine was sporting a full race cam - overall smooth operation is quite a noticeable change.

On another note, I plan to attend OSH next month and hope to put some faces with the names I've become familiar with through the forum.

Mike V.

[fearofpavement]

Re: Tempest

Hmmm, I've never in my pretty long life tested the resistance on a spark plug. Guess i needed something else to worry about.

[astjp2]

Re: Tempest

I added information in the reference forumn

[Robert Lees]

Re: Tempest

I've moved some posts to the Oshkosh 2015 thread, in case you were wondering what happened to them.

Rob

[Mark Julicher]

Re: Tempest

Just switch to Tempest plugs and have no worries. The molded-in resistor is much more resistant to breakdown.
I have been routinely checking spark plug resistance. The electrode must be nice and clean to get a good reading. Typically, plugs with super high resistance also exhibit scorching and arcing inside the ceramic well. Idle and starting show improvement when the plug resistance is correct.

[crispy critter]

Re: Tempest

I know I may be looked down on a bit for asking this but, how do you check the resistance and what is good and not good?

[astjp2]

Re: Tempest

Kevin, check out the info in the reference forum, I left a link to the Mil-spec and the article. Tim

[Mark Julicher]

Re: Tempest

Using an ohmmeter set to 20K, measure the resistance between the center electrode of the spark plug and the ignition lead contact down inside the ceramic well.
You may have to modify one test lead to reach down into the spark plug to make good contact with the ignition contact.
You will have to clean the residue off of the center electrode to get good contact. Either scrape some the residue off, or bead blast the plug. Glass bead or soda will minimize erosion of the plug.
Look for 1 to 5 thousand ohms.

Side Bar: I have seen many plugs that measured a megohm that would still make a blue spark in my tester. Often you will see brown stains, which is evidence of arcing, inside the ceramic well of a high-resistance plug.