Originally Posted by
Glowgeek
High dollar stuff, rated 650°F. I've seen JB cold weld (450°f max) used on glow engine exhaust with satisfactory results but the temps with gas are higher.
New question, what temp is estimated at the plug threads? I have no clue, I just know that much of the heat (972°f-1472°f) at the plug tip is removed/sinked away by the surrounding material.
Normally, just a touch hotter than the rest of the cylinderhead. My cylinder heads show on average some 300F all around, so maybe the threads go to 400F or therabout. Maybe a bit higher, but I would be amazed if it would hit 500F
The plug gets quite a bit hotter, especially at the centerelectrode, isolator nose and the protruding part of the mass electrode, but the threaded part of the plug has only slightly above head temperature.
Please don't take this as being pedantic, it is just to help you understand the matter: "Temperature" is not the same as "heat". The plug tip indeed gets very hot, but it contains very little energy, and the isolator nose quite literally is an isolator, not only for electricity, it also is way less conductive to heat than ordinary metals. That is why you can have a plug tip of around 1500F but 1/8" further down the road a thread temperature of only 400F