Anti seize on spark plugs


do you know the thread size for the plug and chaser?

(Paul Wigton) #7

14mm… all are the same pitch.

(W. Schuster) #8

Use an old spark plug and file a slot along the thread area to make a cutting edge
to clean the dirt from the thread.


(Geo Hahn 1969 Series 2 OTS) #9

I do as noted above plus I always use a torque wrench to tighten the plugs (yeah I know that new plugs usually have a crush washer but that is a one-time thing).

My concern is not that they get tight enough but rather that I avoid over-tightening.

(Clive Wilkinson) #10

I always use the Permatex silver coloured anti-seize for plugs aluminum heads, never the copper based type. Copper and aluminum don’t like each other.

(Erica Moss) #11

Is that a concern without a catalyst? Normally it would be water or water vapor. We have copper washers all over and they don’t seem to cause excess corrosion. The copper in anti seize is suspended in grease which I’d hope would prevent corrosion. Although the nickel product would work just well so no reason not to use it…

(Chris Fell) #12

The problem we have with spark plugs in aluminium heads is not over torquing, but repeated torquing. Aluminium becomes hard and brittle when “worked”, it becomes crystalline and less mailable the more we fit, remove and refit any threaded and torqued fixture. This is one of the main causes of stripped threads in older cylinder heads. Over torquing will also do it, but in a shorter time scale.

Cutting out the old crystallised thread when fitting a Helicoil (other brands are available) cures the problem, for the next 50 or 60 years.

(Robert Thomas 68 FHC ) #13

I’ve always used copper based and never had a problem. I would be very hesitant to install plugs into a dry aluminum head.

(Paul Wigton) #14

Ditto: never seen an adverse reaction, to using copper-containing anti-seize.

(Tom D) #15

First, I DO use anti-seize on spark plugs. But some manufactures say not too, as their plugs are plated to prevent seizing and they say the anti-seize may insulate the plug electrically. Personally, I do not believe the insulation factor, but I thought I would pass on the information.

(69 FHC ) #16

I was told that was the reason to use copper anti seize on the plugs. I don’t use a torque wrench, just tighten them by feel and have never had a problem.

If one googles use of anti seize on spark plugs you find no consistent answer.

(Dick Wells,, 74 OTS UES1S25806BW, 99 XJR) #17

CHAMPION SPARK PLUG ANTI-SEIZE 2612. Recommended/made by Champion, FAA approved for use on all aircraft spark plugs. Runs about $12 for a 4 oz. bottle.


(Tom D) #18

True, but the variation is often because of materials, manufacturers, etc. Which is why, if one desires to be correct, one should follow the procedure for that particular engine/manufacturer/spark plug. So I attempt to follow as I just said, but when in doubt, or no specific information, I default to using anti-seize.

(69 FHC ) #19

As do I. …


I’ve never used anti-seize with cast iron cylinder blocks and never had a problem. I always use it when threading steel into aluminum.


what do you torque them to?

(Erica Moss) #22

Champion says 10-18 ft lbs (14mm into AL head). I do 10-12 and call it a day


thanks------another quick question—given a choice between Aluminum,copper or some other anti-seize grease, which would you use for the plugs?

(Carl Hutchins, Jr. ) #24

Me simplifies. Anti seize on plugs, wherever found, Alloy or iron. Start the plug by hand to assure it is n9t x"d. Finish with a 3/8" drive socket rachet. Oh, chase the threads if any doubt. Not to cut metal, but merely carbon. up and snug is just fine. One expression is “don’t kill it”…


(Paul Wigton) #25

That generally correlates to… making the plug snug, against the crush washer, then 3/4-1 full turn after that.

Never torqued a spark plug in my life: the above was written on a Champion box, when I was a kid…so far, so good!