Tempest (Formerly Autolite) Spark Plug Review

dmccormack

dmccormack

Touchdown! Greaser!
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Dan Mc
I finally put new plugs in the Chief yesterday. I ordered the Tempest 37BYs as they are shorter and $5 less each than Champions. I ordered Sunday, arrived Thursday via UPS Ground from Chief Aircraft in OR.

We ran each old Champion plug through the bomb -- one was shorted out and the rest had varying degrees of poor spark. Ugh.

Then we tested each Tempest -- nice strong, even spark. What a difference! We installed them yesterday, but I wasn't up to flying last night. Taxied over to A&P's hangar while waiting for fog to lift and replaced all the old inspection plates after checking torque on each plug (we used 27 ft/lb -- Lyc manual suggests 300-360 in/lbs).

Started up, taxied out, applied full throttle -- no stumbling!! Takeoff was strong and I was up at cruising altitude in no time. Flew an hour over the gorgeous mid-September landscape, landed at FWQ in the grass for fun, and headed back home to make it home in time for other duties.

I'm very pleased with these plugs. Long term results to be seen, but so far, so good!!

http://www.aeroaccessories.com
 
I've run two sets of "autolite" plugs in an 0-470-L.

Definitely won't do it again. Went back to Champions and I'm much happier (and so is my engine).

YMMV.
 
dmccormack said:
More details, please...?
Click to expand...

Plugs started failing at about 150 to 200 hours in both cases.

Edit: BOTOH I know that some folks have had good luck with them. Similarly, I swear by monster retreads, I've had great luck with them. I know some people that you couldn't pay enough to put a monster on their bird because they've had a bad experience.

In both cases...it is what it is.
 
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I used the Autolite (Unison) plugs for awhile a few years ago after Champion bought out Auburn and shut them down. Had some issues with short life, especially with the UREM37BYs, with the internal resistor failing, and some problems with plug threads being a bit too big and jamming in the plug hole on the head. Finally gave up and went back to Champs. I recently bought a bunch or Tempest's 37BYs again (must be old stock; still have Unison's name on them) and am running them in a couple of the airplanes to see how they do. The 37BY is a great plug for those engines that don't like 100LL and foul their plugs. The BY series plugs are pretty much unfoulable that way.

It's sad that we have to put up with "Aircraft Quality" parts at the prices we pay. Auburn made a sparkplug that was guaranteed for 400 hours and we had very few failures in that time. Nearly every plug eventually eroded to limits and was discarded at around 1000 hours while the internal resistor was still working. The Champions, on the other hand, I've had fail right out of the box, and some are dead at 50 hours. Champion makes no real guarantee; they even recommend replacing the plugs every 50 hours. Their internal resistor is a tiny carbon slug held in place by a small spring and screw, and it seems to lose decent contact after a while. Auburn's and Tempest's have a resistor that's molded into the plug during assembly; Auburn's resistor almost never failed. Unison's did, often. It remains to be seen whether Tempest will fix it and produce an Auburn-quality plug. Then maybe Champion will wish they'd adopted Auburn's methods instead of just closing them up.

This "aircraft quality" thing bugs me. I mounted a brand-new Condor (Michelin) 8.50-6 tire this week and found it out-of-round by an eighth inch or more. This is common for all light aircraft tires. The cheapest car tire runs far more accurately than that and costs half as much. We have to put up with uneven rolling and rumbling on the runway, while ultralights using wheelbarrow tires scoot along smoothly. If we don't dynamically balance our nosewheel tire assembles we'll get shimmy, and the same goes for the tailwheel tires. Until a year or so ago all we could get for tail tires were the STA (formerly McCreary) tires that weren't substantially any different than the Chinese hand-cart tires I see at Princess Auto and that had a really thin carcass and wore out in no time flat. Even if you ordered a tail tire from Scott this is what you got. Now we can get a decent (but still Chinese-made) tire with a lot more strength to it and it runs much more accurately and lasts longer.

Dan
 
The loss of Auburn really bugs me as well. IME they were the best of plugs.
 
FWIW, I've had the Autolite 37BY plugs on my Piet's A-75 for probably 150 to 200 hours now with no issues.
 
SteveR said:
FWIW, I've had the Autolite 37BY plugs on my Piet's A-75 for probably 150 to 200 hours now with no issues.
Click to expand...

Heck, you could probably get away with plugs from a Model T Ford if they fit in the holes.
 
gismo said:
Heck, you could probably get away with plugs from a Model T Ford if they fit in the holes.
Click to expand...

And this is a bad thing because...?

:wink2:

These old tractor-tech airplane engines were dirt simple, low compression, low maintenance.

I wonder how many Turbo-cirri will be flying 70 years from now?
 
dmccormack said:
And this is a bad thing because...?

:wink2:

These old tractor-tech airplane engines were dirt simple, low compression, low maintenance.

I wonder how many Turbo-cirri will be flying 70 years from now?
Click to expand...

Probably they'll be sitting on the ground for lack of 100-octane, while the old A-series powered airplanes will still be running on moonshine or something.

Dan
 
JOOC- why do they put carbon resistors in the plug? Is it because the resistance of the system drops as you form a a spark?

I know that xenon arc lamps form conducting ionized gas after they get started, so the current is regulated otherwise the power supply (and maybe the lamp) gets blown- increased current lowers the lamp resistance, allowing more current...
 
Cap'n Jack said:
JOOC- why do they put carbon resistors in the plug? Is it because the resistance of the system drops as you form a a spark?

I know that xenon arc lamps form conducting ionized gas after they get started, so the current is regulated otherwise the power supply (and maybe the lamp) gets blown- increased current lowers the lamp resistance, allowing more current...
Click to expand...

In an automobile the resistor is there to reduce radio noise. In aircraft, the ignition is usually shielded and the resistor contributes nothing toward noise control. The aviation plug's resistor controls the spark current and reduces electrode erosion.

http://books.google.ca/books?id=A0b...&resnum=7&ved=0CDgQ6AEwBg#v=onepage&q&f=false

or

http://www.championaerospace.com/assets/AV6-R-Nov2004.pdf

"Capacitance after-firing," which is the phenomenon the resistor is supposed to control, is additional, later sparking caused by the discharging of the the charge stored (during plug firing) between the ignition lead's core wire and the shield.

Dan
 
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Thanks, Dan. The Google link had a lot of pages missing (copyright reasons). I suppose the missing section was what you were referring me to.
 
Cap'n Jack said:
Thanks, Dan. The Google link had a lot of pages missing (copyright reasons). I suppose the missing section was what you were referring me to.
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That link should take you to Page 90, and the last paragraph on that page gives the reason for the resistor.

Dan
 
Dan Thomas said:
That link should take you to Page 90, and the last paragraph on that page gives the reason for the resistor.

Dan
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Worked this time. Maybe they randomly cut sections when you visit a book.

Thanks much- clear now.
 
Cap'n Jack said:
Worked this time. Maybe they randomly cut sections when you visit a book.

Thanks much- clear now.
Click to expand...

Must be. I clicked the link, it said 'the page is unavailable or you've reached your viewing limit for this book'. I clicked refresh, and the page appeared.
 
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