Spark Plug Thread Lubrication?

[robert1]

Warpspeed, I have a question for you. On some of the SB2 stuff I've done the electrode breaks off of the plug at the base. I've talked to others that have seen the same thing. And no it's not detonation burning the electrode off, they just break off. I see the Cup guys are using X plugs, did they go this route because of this?

[JoePorting]

What is the deal with those Autolite X plugs (3910X, etc...). I bought about 5 sets of those on ebay back about a year ago because I thought they would work good. I thought they worked slightly worse then a regular plug, but other people claimed other results. Now you can't buy them anywhere, and people are claiming that they were only made for the cup teams. ??? I hear of people paying $20 or more a plug to try and get them. If they're so good, why doesn't Autolite sell them to everyone???

[af2]

I hear of people paying $20 or more a plug to try and get them. If they're so good, why doesn't Autolite sell them to everyone???

They will

[Piledriver]

A wise man once told me to coat Milk Of Magnesia on plug threads in aluminum heads...

After I stopped laughing about the concept, I found it works very well, and has ~no effect of the heat range etc.
(Apparently an old turbine mechanics trick)

Also: Decent spark plugs (Bosch/NGK/Nippondenso, probably some others) are nickel plated.
These tend to come out.

Champions/Autolites generally are not, and prefer to corrode in place, at least on an air cooled VW/Porsche...
(Probably anything air cooled or with alloy heads)

I absolutely guarantee there is a spark plug torque spec in the manual for your car.
Too LOOSE can cause as many issues as too tight.

[RW TECH]

A wise man once told me to coat Milk Of Magnesia on plug threads in aluminum heads...

After I stopped laughing about the concept, I found it works very well, and has ~no effect of the heat range etc.
(Apparently an old turbine mechanics trick)

It's widely used in the gas turbine world & doesn't create disasters like metalic lubes would, especially aluminum. I used to work in aerospace & remember a time when a guy left an aluminum tool on the top of a furnace vat then put the batch of parts in the vat through heat treat.

When it was done the vat had a slot cut in it and all the parts inside were destroyed.


As far as effect on heat range for spark plugs, is that something you know to be verified or is it an assumption? For it to have no effect means milk of magnesia has no insulative characteristics and has equal or greater thermal conductivity characteristics to aluminum.

[MadBill]

Let's keep this all in perspective. Goobering lubricant on the plug tip is just plain incompetence and thermal conductivity through the threads is only one of at least half a dozen factors that will affect a plug's operating temperature; in my estimate far from the the most important...

[RW TECH]

Let's keep this all in perspective. Goobering lubricant on the plug tip is just plain incompetence and thermal conductivity through the threads is only one of at least half a dozen factors that will affect a plug's operating temperature; in my estimate far from the the most important...

True up to the point where you run into something like this:


"We use Coposlip high temp anti-sieze on the threads of all of our spark plugs. We have done extensive testing with Bosch on this, and this is about the only lube that provides the best grounding and temp transfer, while still providing the needed lubrication to get them out without damage. You do need to keep it off of the exposed chamber area as it can cause a misfire/detonation as mentioned by others, but as far as changing the heat range, it has shown VERY little to no effect. The metal particles in the lube help ensure the needed grounding (this is one of the most important grounds in the entire system) just don't get carried away with the amount to avoid chamber contamination!

We used to use EPL, engine oil ect. on the threads, but again, after testing different lubes, found the anti-sieze to be the best.

This testing all came about during the early 2000's. AC Delco was pulling back their motorsport efforts, and due to this, they started having some quality control issue's with their plugs. We started breaking pieces out of the intake valves on high duty cycle tracks (Michigan, Chicago ect), and after chasing just about everything in the book, we found the plug threads to be undersize from the sae spec. This was having a huge impact on heat transfer, and effectivly raising the heat range of the plug into the danger zone for our extended full throttle applications. This is what started all the plug and lube testing, and it is something we continue to monitor constantly.

Proper torque is VERY critical also, as thread engagement (as stated above) has a huge effect on the plugs ability to cool. Most plugs need to be torqued 15-18ft/lb, but can vary slightly with manufacture. Plugs with a compressible sealing washer should be installed, torqued, loosened and re-torqued to pre-compress the washer, thus ensuring the proper thread engagment and heat transfer during operation.

[vincenelson]

After loosing threads on some rather expensive aluminum cylindar heads I now use just a little silver goop on the plug threads, it has a 1500 degree temp range. It is very expensive. The silver content makes for good electrical properties and heat conduction. One little tube will last you ten years.

[SchmidtMotorWorks]

Proper torque is VERY critical also, as thread engagement (as stated above) has a huge effect on the plugs ability to cool. Most plugs need to be torqued 15-18ft/lb, but can vary slightly with manufacture.

I have known a lot of guys that think plugs should be installed finger tight.

[SG4247]

One day an engineer from Kerr-Mcgee gave me a bottle of pure Nickel never seize and said use this on plugs, throw the copper in the trash. We have since built, raced an dynoed a bunch of BBC chevys with aluminium heads over the years with great results. So now we only use Nickel antiseize. Never had plug issues....and never had heat range issues, or fouling using nickel anti seize either. The copper stuff would disappear eventually from the threads...the nickel does not. Doesnt matter how long they are left in. A thin coat on the threads, torque it to spec, and its good to go.

Check this...

http://www.jdindustrialsupply.com/punisp.html

Works for us..

GB

[MadBill]

"I have known a lot of guys that think plugs should be installed finger tight."

Here's what "finger-tight" does to stock heat range ACs in a 1989 Firebird 305 TPI after a few flat-out laps of the Atlanta road course. Note that not only have the center electrodes disappeared, the ceramic insulators have softened (melting point of aluminum oxide is 3600°F.) and slumped to one side, like The Tower of Pisa...

[wjnielsen]

"I have known a lot of guys that think plugs should be installed finger tight."

Here's what "finger-tight" does to stock heat range ACs in a 1989 Firebird 305 TPI after a few flat-out laps of the Atlanta road course. Note that not only have the center electrodes disappeared, the ceramic insulators have softened (melting point of aluminum oxide is 3600°F.) and slumped to one side, like The Tower of Pisa...

Bill, that's an ugly pic. Hopefully nothing else suffered too bad.

A wise man once told me to coat Milk Of Magnesia on plug threads in aluminum heads...

After I stopped laughing about the concept, I found it works very well, and has ~no effect of the heat range etc.
(Apparently an old turbine mechanics trick)

Also: Decent spark plugs (Bosch/NGK/Nippondenso, probably some others) are nickel plated.
These tend to come out.

Champions/Autolites generally are not, and prefer to corrode in place, at least on an air cooled VW/Porsche...
(Probably anything air cooled or with alloy heads)

I absolutely guarantee there is a spark plug torque spec in the manual for your car.
Too LOOSE can cause as many issues as too tight.

Well, I'll stand corrected if someone wants to say that oil won't keep their Champion or Autolite plugs from sticking for a year... All I've used since I started working in shops has been Bosch on Euro stuff and NGK on damn near everything else.

I'll add milk of magnisia to the list along with iodine, as things I'd have NEVER thought of until I was told! Live and learn, huh?

-Bill

[MadBill]

...Bill, that's an ugly pic. Hopefully nothing else suffered too bad....
-Bill

It pinched the top rings and tuliped the intake valves enough to use up all the lifter travel, but we backed them off and finished out the day

[rskrause]

A dab of "never seize". Seems to work fine.

[nissan-lover]

Magnesia makes sense as it is the usual filler in all your kettle and oven elements, good thermal conductivity, soft, and a high melting point, higher than alumina from memory? the only down side is it is an insulator, but the soft part means it will get pushed out the way.

Mike