Anti-seize on spark plug threads

Steel and aluminum are both anodic dissimilar metals which is a good reason to coat the threads with a barrier like copper or nickel.
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But this statement you made is just wrong. All metals are dissimilar, just a matter of how dissimilar. Steel and aluminum are quite close galvanically. Much closer than copper and aluminum. So adding a “barrier” of copper between the steel and aluminum will only make any galvanic reaction worse.

I know that it is not a problem in terms of anti seize, but it pertains to other areas in the airframe, like using a brass or copper fitting with an aluminum AN fitting.
 
Dana said:
Like using the wrong anti-seize? :eek:
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So much for using better modern materials.

I guess using a Superior Cylinder will never be Approved :)
 
I know that it is not a problem in terms of anti seize, but it pertains to other areas in the airframe, like using a brass or copper fitting with an aluminum AN fitting.[/QUOTE]

I was talking about anti seize...
 
Doug Reid said:
I know that it is not a problem in terms of anti seize, but it pertains to other areas in the airframe, like using a brass or copper fitting with an aluminum AN fitting.
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I was talking about anti seize...[/QUOTE]
But you still won’t admit that copper is worse for aluminum than steel in terms of galvanic corrosion and that you said “coating” the threads in copper would protect the aluminum when the exact opposite is true. Steel is coated in cadmium or zinc to protect aluminum. Zinc being more sacrificial than aluminum and cadmium being just a little closer to aluminum on the galvanic series than steel is.
 
The sparkplug gaskets are made of copper, and they're in firm contact with the aluminum head. Take a look sometime at an older engine and see where the corrosion is: It's around the gasket, not under it. If water (electrolyte) can't get under the gasket, corrosion isn't going to happen. If water can't get into the sparkplug threads, it isn't going to happen, and I never once, in thousands of instances of sparkplug servicings, found any in there.

Besides that, Lycomings come with a stainless steel helicoil already in the plug threads. Seen that in some others as well. Some Continentals had a steel insert that threaded into a larger thread in the head and was rolled over on the inside to trap it there, like a big, hollow, threaded rivet.

One can use the typical Nevr-Seez, which is aluminum and graphite, like generations of mechanics have used for years, and have no problems. The graphite is the anti-seize. Champion's and Tempest's anti-seizes are just graphite.

Way too much overthinking here.
 
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