Tempest plugs

Lachlan

Lachlan

En-Route
Joined
Sep 23, 2015
Messages
3,813
Location
North Creek, NY
Display Name
Display name:
Lachlan
I’m going to put a new full set of spark plugs on my O-200 in my ‘76 C150M. I’m debating on going with massive electrodes all around, as they’re still much lower in resistance than the Champions that are in there now, or going with fine wires all around. Massive electrodes are $27.50 each; fine wires are $87.50 each, so I was strongly considering massive a on top and fine wires on the bottom. This is relatively common, but I’m curious if anyone here has any additional advice. If I was wealthy I would just buy 8 of the pricey ones and 8 of the cheap ones and have my butler compare them while I fly around in some other expensive airplane. I’m not wealthy. :) Thanks for any tips or helpful suggestions.
 
Massive all around.

that said my mooney came with new fine wires that still look brand new after 500 hours on them. I may never have to buy plugs again at this rate. I’d still buy massives.
 
Salty said:
Massive all around.

that said my mooney came with new fine wires that still look brand new after 500 hours on them. I may never have to buy plugs again at this rate. I’d still buy massives.
Click to expand...

I’ve heard lots of stories of Tempest plugs lasting over 1600+ hours and still having really low resistance. Massives are a bargain, especially vs fine wire fir a set of 8. It is a difference of $480. Easy decision, unless there was some major reason to buy find wires.
 
I’m no expert. Did some research and decided on 24 Tempest Massive’s for my bird. Been good for a couple hundred hours. Remind me in a few more years and I’ll give you a better longevity PIREP.
 
I had a Tempest massives in my O-320, worked great.

In my IO-390 I have Tempest massives on top & fine wires on bottom. I’m not trying to overthink it, just thought I try the mix.

So far things are going just great.
 
If I were you I’d just buy the Tempest ones and I have done so twice now. REM37BY’s are where it’s at. I no longer have any lead fouled plugs on the O-200 and the rear end tells me it’s a smoother ride. For what it’s worth the Champion REM40’s would always foul up.
 
GLDP said:
If I were you I’d just buy the Tempest ones...
Click to expand...

That’s what I’m buying. I’m just trying to make sure I won’t regret buying the less expensive massives over the spendy fine wires.
 
I think massives are just fine for most of us. That’s what the plug booth guy at Oshkosh said too, FWIW.

Another biggie is proper leaning.
 
GLDP said:
If I were you I’d just buy the Tempest ones and I have done so twice now. REM37BY’s are where it’s at. I no longer have any lead fouled plugs on the O-200 and the rear end tells me it’s a smoother ride. For what it’s worth the Champion REM40’s would always foul up.
Click to expand...

That there. The UREM37BY is quite fouling-resistant, an important trait in the O-200, which has a reputation of fouling the bottom plugs. The plug hole is low in the cylinder and any oil that gets past the rings at idle, especially when the engine is cold, runs in there and gets cooked and shorts the plug. The 37BYs stick their electrodes out, clear of the sparkplug well. I had good success with them in the O-235s as well.
 
Dan Thomas said:
That there. The UREM37BY is quite fouling-resistant, an important trait in the O-200, which has a reputation of fouling the bottom plugs. The plug hole is low in the cylinder and any oil that gets past the rings at idle, especially when the engine is cold, runs in there and gets cooked and shorts the plug. The 37BYs stick their electrodes out, clear of the sparkplug well. I had good success with them in the O-235s as well.
Click to expand...

Alright, I'm done with that one. Now I just need to convince myself to keep flying while the season still allows it and wait til the snowy downtime to put my new plugs in. (I'll likely wait til Spring and change them out right before the first flight of the year, at this point. We get snowed in before Thanksgiving, typically, and it's a grass runway so it won't get plowed.) Thanks to all for the affirmation and the tip on the 37BY plugs.
 
What is the difference between a massive and fine wire plug? I’m completely ignorant on this and fly OPs little cousin the c85 with the 0-200 crank n jugs...
 
Huckster79 said:
What is the difference between a massive and fine wire plug? I’m completely ignorant on this and fly OPs little cousin the c85 with the 0-200 crank n jugs...
Click to expand...

If you have the time (warning 1.5 hours)

 
I’m looking switching to Tempest fine wire for my O-470R turbo, and trying to collect data for the decision as well. I’m currently running Champion massive electrode. Never really any fouling issues, but I lean aggressively on the ground too.
 
Massive plugs. You don't need fine wire on an O-200.

Fine wires start to make sense if you're on a high performance engine. I ran them on the 414 for instance, but ran massives on the 310.
 
Ted DuPuis said:
Massive plugs. You don't need fine wire on an O-200.

Fine wires start to make sense if you're on a high performance engine. I ran them on the 414 for instance, but ran massives on the 310.
Click to expand...

Another reason to love a 150 (or anything with @ small Conti) is not needing to buy the expensive stuff. I lean consistently and my plugs always look good and don’t need a lot of cleaning, just replacement. I have two different types of Champion plugs on it now, I want a full set of Tempest plugs. I’ve read anecdotal reports of smoother running in the O-200 with Tempests. Could be due to old, high-resistance plugs vs brand new Tempest plugs, not sure... either way, I’m going with the massive version on my minuscule engine.
 
And how do you think it would run if you replaced old Tempest plugs with brand new Champions? And you say "my plugs always look good". So how is it running now with the current plugs? Are you flying with a rough engine now? Tempest does have a good pr, (that is anecdotal reports) campaign. Ever look at what brand of plugs Lycoming and Continental supply in their factory new engines?
I have fine wire plugs in my Bonanza which Ive owned for 15 years. I don't recall ever having to change a plug due to worn electrodes, have had one or two crack. My engine monitor doesn't show any problems with a cylinder or plug. I live at 8000 ft and have flown to 20,000. Also have a Cub with a C-85 with plain Champion plugs, massive and don't recall ever having one foul. I don't lean as it doesn't have a mixture control. It starts on first or 2nd pull, I don't have any idea what the plug resistance is, but it runs well.
 
Last edited:
Bill Greenwood said:
And how do you think it would run if you replaced old Tempest plugs with brand new Champions? And you say "my plugs always look good". So how is it running now with the current plugs? Are you flying with a rough engine now? Tempest does have a good pr, (that is anecdotal reports) campaign. Ever look at what brand of plugs Lycoming and Continental supply in their factory new engines?
I have fine wire plugs in my Bonanza which Ive owned for 15 years. I don't recall ever having to change a plug due to worn electrodes, have had one or two crack. My engine monitor doesn't show any problems with a cylinder or plug. I live at 8000 ft and have flown to 20,000. Also have a Cub with a C-85 with plain Champion plugs, massive and don't recall ever having one foul. I don't lean as it doesn't have a mixture control. It starts on first or 2nd pull, I don't have any idea what the plug resistance is, but it runs well.
Click to expand...

Business decisions in many cases trump engineering decisions. I have never heard of, nor had, any problems with Tempest plugs.

I have heard of (and had) problems with Champion plugs - many in fact.

Champion has good, long-standing relationships with a number of bigger companies. Those relationships are hard to change and there are business reasons why they make sense on a cost or ease of acquisition perspective.
 
I had the old-style Champions (prone to resistor failure) and replaced them with massive-electrode Tempests in my IO-320. Runs about the same, but starting is now considerably easier.

I lean for taxi and run LOP a lot, so no issues with lead accumulation. The electrodes do wear enough to justify re-gapping every 100 hours, and I media-blast them just for good measure.
 
Bill Greenwood said:
And how do you think it would run if you replaced old Tempest plugs with brand new Champions? PROBABLY AS WELL OR BETTER. And you say "my plugs always look good". So how is it running now with the current plugs? QUITE WELL. Are you flying with a rough engine now? NOPE, NOT AT ALL. Tempest does have a good pr, (that is anecdotal reports) campaign. Ever look at what brand of plugs Lycoming and Continental supply in their factory new engines? OF COURSE.
I have fine wire plugs in my Bonanza which Ive owned for 15 years. I don't recall ever having to change a plug due to worn electrodes, have had one or two crack. My engine monitor doesn't show any problems with a cylinder or plug. I live at 8000 ft and have flown to 20,000. Also have a Cub with a C-85 with plain Champion plugs, massive and don't recall ever having one foul. I don't lean as it doesn't have a mixture control. It starts on first or 2nd pull, I don't have any idea what the plug resistance is, but it runs well. YOU SHOULD BE SURE TO CHECK THE RESISTANCE OF EVERY PLUG NEXT TIME YOU HAVE THEM OUT.
Click to expand...

CAPITALIZED/BOLDED for easier differentiation of your questions and my answers. Engine is running great, but internal resistance of a few plugs is a bit higher than I would like. This happens to certain brands/types of plugs. My electives are not noticeably worn, the gaps are correct (according to IA @ annual less than 2 months ago.) I have two different part numbers of approved plugs on my engine now. I want to change them out for new plugs and use the best option, so I’m asking my pals on PoA. ;)
 
Whenever you get this figured out, I’ll do the same for my 150F O-200. My plugs are not getting their resistance checked at annual, but run fine. However they look old as dirt and are probably 15 years old from the last overhaul.
 
Matthew Rogers said:
Whenever you get this figured out, I’ll do the same for my 150F O-200. My plugs are not getting their resistance checked at annual, but run fine. However they look old as dirt and are probably 15 years old from the last overhaul.
Click to expand...

It’s all settled as to what I’m buying. UREM37BY x8. Just not sure when I’ll put them in. Probably over the winter while I’m stuck in the hangar.
 
  • Like
Reactions: Ted
What is your objective? I wonder when you say they run fine, but you want to replace them? I guess in my planes, I value how they run, don't know about the Tempest resistance case.

Ted, what do you base your trouble with Champions on? I have never seen any real factual data such as any kind of objective engine test by Consumer Reports. If you fly a twin have you tried putting new Champions in one engine, Tempest in the other and flying for a few hundred hours? Or just relying on hearsay and rumor? Have you had rough engine making a forced landing or had to take it in for service due to rough engine? Lets say Tempest has been around 15 years. How was your engine running before that? Were you flying around with a rough engine or with a miss in it?

I admire marketing, I made an A in it in college, and Tempest has done a good job of it. I'm a little skeptical, such as when I turn on late night tv and William Devane, with his photo of a battleship is telling everyone to buy gold.
 
Last edited:
NordicDave said:
I’m looking switching to Tempest fine wire for my O-470R turbo, and trying to collect data for the decision as well. I’m currently running Champion massive electrode. Never really any fouling issues, but I lean aggressively on the ground too.
Click to expand...

Ditto for me. Champion massive electrode and aggressive leaning on the ground (and at altitude). In fact my usual leaning at idle on the ground requires me to bump the mixtures up a bit before starting to advance the throttles for taxi or the engines threaten to quit.

Lachlan said:
YOU SHOULD BE SURE TO CHECK THE RESISTANCE OF EVERY PLUG NEXT TIME YOU HAVE THEM OUT.
Click to expand...

Got no dawg in this fight (in fact the only Dawg I own is the Husky ;) ). But I have run Champions in the Aztec since I bought it in 2012. Now on my second set. A few years ago I read something (Tempest website perhaps) about checking the resistance of the plugs. I tested all 24 Champions the next time I had them out. All but two failed the resistance check. Badly. Since the plane seemed to be running fine, and I couldn't see springing for 22 new spark plugs, I re-installed all 24 after cleaning and re-gapping them. Plane ran smoothly, cold starts typically two, max 3 blades (hot starts depend on how the planets are aligned). Still the same to this day. Still the same 2nd set of plugs. I usually clean, regap and rotate the plugs every 75 to 100 hours. I have never bothered with that resistance check since.
 
Call to the engineers and mechanics - what damage does a high resistance spark plug (failed test champion) do to the engine, magneto, wires, etc? Does it only caused some suspected reduced engine performance, or cause some degradation?
 
GRG55 said:
Ditto for me. Champion massive electrode and aggressive leaning on the ground (and at altitude). In fact my usual leaning at idle on the ground requires me to bump the mixtures up a bit before starting to advance the throttles for taxi or the engines threaten to quit.



Got no dawg in this fight (in fact the only Dawg I own is the Husky ;) ). But I have run Champions in the Aztec since I bought it in 2012. Now on my second set. A few years ago I read something (Tempest website perhaps) about checking the resistance of the plugs. I tested all 24 Champions the next time I had them out. All but two failed the resistance check. Badly. Since the plane seemed to be running fine, and I couldn't see springing for 22 new spark plugs, I re-installed all 24 after cleaning and re-gapping them. Plane ran smoothly, cold starts typically two, max 3 blades (hot starts depend on how the planets are aligned). Still the same to this day. Still the same 2nd set of plugs. I usually clean, regap and rotate the plugs every 75 to 100 hours. I have never bothered with that resistance check since.
Click to expand...

That’s good to know about failing resistance checks but still running well. I think there’s more chance of magneto damage if the resistance goes higher than 6-7k Ohm but otherwise unlikely.

My plugs are old and mismatched, and I’m replacing them with Tempest plugs just because of their slick marketing program. Who can resist? (Get it? Resist? Spark pkugs? Resist?) Their PR dept is working some serious OT and it finally paid off in the form of a colossal sale of $220 worth of plugs to an amazing O-200 that ran pretty well on old mismatched Champions, but with Tempest plugs it’s gonna get at least another 25 knots of horsepower per hour at idle. I know @Bill Greenwood will laugh at me for falling prey to that gimmicky commercial that pops up on every tv show and every website, but I just can’t stop thinking about those spark plugs... it’s like the mere thought of spark plugs ignites this hurricane of thoughts, a tornado of wish and wanting, a tsunami of desire, a squall, a.... a TEMPEST of emotions storming through my tiny little carbon-fouled black heart! I’ve just gotta have em!!!
 
I just overhauled both my magnetos (admittedly they went 700 hours) but they did have distributor damage. Maybe that was exacerbated by the old champions. Since I am a new pilot and aircraft owner, I have not started taking out my plugs and resistance checking them myself and my mechanic is on the side of “it runs well, plugs are fine” fence.
 
Lachlan said:
That’s good to know about failing resistance checks but still running well. I think there’s more chance of magneto damage if the resistance goes higher than 6-7k Ohm but otherwise unlikely.

My plugs are old and mismatched, and I’m replacing them with Tempest plugs just because of their slick marketing program. Who can resist? (Get it? Resist? Spark pkugs? Resist?) Their PR dept is working some serious OT and it finally paid off in the form of a colossal sale of $220 worth of plugs to an amazing O-200 that ran pretty well on old mismatched Champions, but with Tempest plugs it’s gonna get at least another 25 knots of horsepower per hour at idle. I know @Bill Greenwood will laugh at me for falling prey to that gimmicky commercial that pops up on every tv show and every website, but I just can’t stop thinking about those spark plugs... it’s like the mere thought of spark plugs ignites this hurricane of thoughts, a tornado of wish and wanting, a tsunami of desire, a squall, a.... a TEMPEST of emotions storming through my tiny little carbon-fouled black heart! I’ve just gotta have em!!!
Click to expand...

Hey, if your whole set of plugs is coming to the end of its useful life and you are going to replace them, probably worth it to try a different brand and see how they perform. Nothing wrong with that. I'd probably do the same. I might even get around to maybe try them on one engine of my plane some day and see if I can notice any difference left to right. But if I do I won't be going into it with any big expectations there's going to be some remarkable improvement in performance or longevity (sort of how I look at the F150 vs Silverado, or Boeing vs Airbus debates :D).

The absolute worst thing that could happen to us airplane owners is only having one option to purchase a consumable like spark plugs from. :(
 
Tempest versus Champion:

The Tempest plug is an outgrowth of the old Auburn plugs. Auburn built their plugs with a molded-in resistor ("monolithic") that was firmly and permanently bonded between the connector well terminal and the center electrode. Those plugs were guaranteed for 400 hours and often went 800 or more, at which time the electrodes were eroded enough to need replacement but the internal resistance was just about exactly as it had been when the plug was new. Champion, for decades, had a resistor that was a little cylindrical carbon slug that was dropped into the well, a spring followed it, and a short screw-cap held it all together. There was minimal contact area between the resistor and its contacts, and as vibration and heat were added, that slug would dance around in there some and the contact would start to suffer and resistance would rise. These things were so sensitive that you could test a plug (one eroded past further use) and see it spark under pressure, then take that resistor/spring/screw out, look at them, put them back in, retest the plug and it would refuse to fire. Or drop that plug on the floor and it would often not fire anymore. Drop an old Auburn on the floor and it usually didn't care; would continue to spark just fine. Much more robust. Of course, never reuse a plug dropped on a concrete floor. You might have cracked the ceramic.

Champion bought up Auburn about 12 years ago and shut them down. They continued to build their loose-resistor plugs until so many of us complained that about three or four years ago they adopted Auburn's monolithic resistor. Did that real quietly; the only hint was that the new catalog showed the molded-in resistor, finally. There are probably still old-design Champs on vendor shelves; to tell them apart, look down the connector well and see if the round silver doodad down there has a screwdriver slot in it. If it does, it's an old plug. No slot is a new plug.

Resistance does matter, even if Champion used to claim that it didn't. A high resistance cuts off the spark much sooner than the engineers intended, which can lead to misfiring, hard starting, arcing inside the magneto distributor, maybe more. Power can suffer some. A spark isn't just a spark; the strength and duration of the spark is important to good ignition and engine performance. As cylinder pressures rise it gets harder to spark, since air is a dielectric and when we pack enough of it between the electrodes we might not get any spark if the plug's resistance is too high or the mag is out of tune or we have a bad ignition lead. With two mags we often won't notice that one isn't firing every cylinder under heavy load unless we do a mag check in that condition. Some mild roughness might be apparent, though.

Champion's plug servicing manual. Some good info on the different plug types here: https://www.championaerospace.com/wp-content/uploads/2015/06/AV6-R-Aug20141.pdf

Tempest's plug cleaning instructions: https://www.tempestplus.com/Portals/0/PDFs/MaintenanceandService/Sparkplug Cleaning The Right Way 081412.pdf

Note that REM37BY or UREM37BY plugs aren't for every engine. Check the chart. http://www.aircraftspecialties.aero/content/TempestAppChart.pdf
 
Last edited:
Ok, so the chart shows UREM40E as the only plug option for all versions of the O-200. Ummm, does that change your mind @Lachlan?

Any one know if the choice of plug changes for an O-200 running almost all auto fuel?
 
asicer said:
Does an EIS change that equation?
Click to expand...

Nope. It's not so much about knowing what the engine is doing, more just that the engines run smoother and the fine wire plugs make a bit better combustion which you notice on higher power engines.
 
As I wrote, what is your objective? Is if to have an engine that runs well? That is mine, but Im old fashioned. I was an honor grad of Air Force mechanic school, and that was decades ago. but I don't recall any instructions about resistance in spark plugs.

Now if your engine is running well, but you feel degraded cause your neighbor has a new brand of plugs. by all means change them. Sort of like when your wife has a I phone 9 and her sister gets a 10 for her birthday. You better go get that 10 asap.
Now if you engine is not running well, especially if you have an engine monitor that shows a bad plug in a cylinder. by all means change that plug. Or to be really happy replace all the plugs with new ones. I don't really have any advice if you replace with a whole set of Tempest, and it still doesn't run well,or if you already have Tempests and it doesn't run well, like one at a Colorado OH shop.
We had bout 17,000 planes at Oshkosh, and I don't recall many or even any making an emergency landing with a rough engine and bad plug. Maybe they all already had new Tempests or maybe they were just lucky.
There is kind of a parallel these days with beer, Budweiser is trying to convince the public that Miller and Coors have corn syrup or some defective ingredient, lot's of ads,
 
Last edited:
Matthew Rogers said:
Ok, so the chart shows UREM40E as the only plug option for all versions of the O-200. Ummm, does that change your mind @Lachlan?

Any one know if the choice of plug changes for an O-200 running almost all auto fuel?
Click to expand...

Not so fast. Check Champion's plug chart for the Cessna 150: http://www.championaerospace.com/assets/AV-14-Jan2010.pdf
It shows the REM37BY as an alternate plug.

The TCDS for the O-200 also shows the REM 37BY as acceptable on it. http://rgl.faa.gov/Regulatory_and_G...2a94fb86257ba6006536f4/$FILE/E-252_Rev_34.pdf See Note 7. (There's a typo in the TCDS where it says Note 6 describes the plugs.)

Either Tempest's chart is deficient or they didn't test their UREM37BYs in the O-200.
 
Bill Greenwood said:
As I wrote, what is your objective? Is if to have an engine that runs well? That is mine, but Im old fashioned. I was an honor grad of Air Force mechanic school, and that was decades ago. but I don't recall any instructions about resistance in spark plugs.
Click to expand...
I didn't get any training on sparkplug resistances either, but I started looking into it when so many Champs were failing on the tester while the Auburns and later on the Unison Autolite and Tempests were just fine. I got engines to run smoother and with better power when I put good plugs in them.

See this: https://www.qaa.com/resource-center...s-the-right-way-to-check-spark-plug-resistors

And this, about Champion's eventual fixing of their problem: https://blog.aopa.org/aopa/2015/03/19/champion-from-denial-to-acceptance/
 
"when so many Champs were failing on the tester"? Is this the Champion test stand where you test the spark under pressure and see it visually through the window? Pretty much the only plugs I have seen fail were cracked ones, and I have had 2 or 3 cracked plugs over about 15 years in one plane.
Ive never seen a Auburn or Autolite aviation plug nor tested one or seen it tested.
 
Last edited:
I remember years ago just prior to the demise of Auburn whenever you ran across a Champion rep he was always trying to give away a set of plugs. Some would take them but most wouldn't. Finally one day at the local parts house an old guy got tired of the free pitch, accepted a set of plugs and promptly threw them in the trash, stating to the rep if he was smart he'd throw the rest of his plug stock in the same bin and get a better job. The rep's look was priceless. But FWIW, I fixed more problems by replacing Champion plugs with Auburn plugs by a huge margin.
 
Matthew Rogers said:
Ok, so the chart shows UREM40E as the only plug option for all versions of the O-200. Ummm, does that change your mind @Lachlan?

Any one know if the choice of plug changes for an O-200 running almost all auto fuel?
Click to expand...

Zoom in. This is the chart from the Tempest website...

9639471D-4024-4969-8B11-A70EBD4B7D92.jpeg
 
Last edited:
You must log in or register to reply here.
Back
Top