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Aviation Spark Plug With the most automated manufacturing processes and the most innovative spark plug in the aviation industry. Made in USA.

High Conductivity Copper Core Center Electrode copper, co-extruded inside a nickel alloy sleeve ensures outstanding heat and electrical conductivity while the nickel sleeve offers high resistance to corrosive combustion gases.

High Alumina Ceramic Insulator high mechanical strength, superior dielectric properties, proprietary protective glaze, provides high performance to conquer severe operational conditions. "Clean Collar" massive electrode "V" tip focuses heat to reduce fouling and enhance heat range control.

Proprietary Glass Center Seal 21st century 'fired in' resistor replaces the multipart screw, spring, carbon pile stack up used in competitive plugs and known to suffer from resistance value instability that can cause misfires, wasted fuel, engine roughness.

Nickel Finish environmentally preferable electrolytic nickel provides outstanding durable finish, superior corrosion protection, and extreme wear resistance.

Nickel Ground Electrodes aviation grade nickel electrode design focuses on minimizing sparking voltage requirements while maintaining specification gaps to ensure large, stable 'flame kernels' for on-time ignition and complete combustion.

Vacuum Infused Center Electrode proprietary, vacuum infusion process seals electrode/insulator gap providing stable heat range and superior center electrode cooling (heat flow to the insulator).

Hot-Lock Assembly intense pressure and heat create positive, zero-leakage, shrunk in seal between insulator and shell to contain the hot, high pressure combustion cycle gases.

Harness Wire Contact smooth, uninterrupted, oxide treated spring contact surface offers enhanced corrosion resistance, is chemically bonded to the fired-in resistor providing the ultimate harness/spark plug termination integrity and energy transfer.

Application Guide

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prefer these plugs to the champion plugs.

Nicholas C
July 6, 2020

I am a aircraft mechanic/IA I bought these spark plugs to keep ad back up. For a dropped plug or bad plug found during inspection.

Chris M
May 24, 2020

They sell my product at their stores, But being they do I should be loyal. But like old habits!! you have to shop!!!!! But doing so !!! I found out The Co. had the best price other than a E bay , very little even their. So I guess it is faster and simple just open the book and order.. SAVE TIME AND !!! MONEY. SOME VENDERS WERE $10.00 HIGHER PR PLUG. AIRCRAFT SPRUCE IS EASY AND FAST.

May 10, 2020

Good plugs. All checked at appx 1600 ohms and we’re ready to install. Running well on my engine.

Richard C
April 30, 2020

Well. Theyre spark plugs. I dont understand why theyre so expensive, since they havent changed in over half a century, but it is what it is. ACS prices were at least as cheap as anyone elses, fast shipping, good service.

Michael V
April 16, 2020

Great price, fast shipping!!

Holly L
February 29, 2020

The Tempest plugs UREM40E are perfect for my Aeronca Champ O235 Lycoming.

February 27, 2020

Great pricing and quick delivery

Robert W
February 23, 2020

Working great ,better starts and less mag drop

February 7, 2020

New Sparkers working perfectly. Eliminated some vibrations that the worn out plugs were introducing.

January 13, 2020


Q: Does Tempest provide the copper gasket on the UREM40E? Or purchased separately?

Each Tempest spark plug will come with one copper gasket. Any additional gaskets must be purchased separately.

Q: Is the Tempest UREM40E the equivalent of the Champion REM40E? I hope so as I have just ordered 8 UREM40E's?

Yes, the Tempest UREM40E is a direct replacement for the Champion REM40E. Both with work in the same applications.

Q: What size copper gasket is required with the Tempest UREM40E plugs, 14 or 18mm?


Q: The Champion chart calls for a REM40E in a Continental W-670 while Tempest calls for a UREM38E. Why does Tempest call for a colder plug in the same application?

The heat ranges actually overlap each other. You can use either one.

Q: What size is the UREM40E? 5/8 or 3/4 ?

5/8 inch.

Q: Is a fine-wire plug available for the UREM-40E?

UREM38S is the fine wire version of UREM40E.

Q: Does the Tempest UREM40E gap come pre-set?

Yes, these will come pre-gapped within a certain range. The end user will need to verify with their application on what gap they are actually needing. The massive plugs are gapped .016" to .021" and the fine wire are .017 to .021".

Q: Are Tempest UREM40E spark plugs identical in dimensions as the Champion REM40E? The cowling has bump outs for the spark plugs so the dimensions are critical for proper clearance.

Yes, the physical dimensions are the same for both brand plugs.

Q: Are these Tempest UREM40E plugs considered "Long reach" spark plugs?

These are not. UREM37BY would be considered long reach.

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