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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
"Virtually all spark plugs now feature a special anti-seizure nickel or zinc-chromate shell plating. Basically, you can think of the plating as a replacement of thread compound or copper slip."
I always use a small amount of anti-seize on the threads being careful to avoid getting anything on the tapered seat. Can't say it makes a difference other than never having had a stuck spark plug or fouling due to contamination in the over 25 years since I got back into the hobby/sport.
That's on iron heads. It's especially important on aluminium heads.
Ask anyone with a Ford Triton V-8 if antiseize compound on spark plug threads is a good idea or not. Those who say "not" have probably not had one long enough to change the heads yet (a common part of replacing spark plugs in those).
And I've seen the broken spark plugs that come out and the metal thickness at the failure point is about 0.015" or so, really thin. And it's disaster when it happens.
To avoid over torquing with anti-seize, hints/advice would be useful for those who wish to use anti-seize without a torque wrench or where one is impossible to use.
JamesC
Last edited by JamesC; 09-22-2021 at 08:38 AM.
Reason: Clarity
I change plugs often enough to not need To worry about them seizing up lol never used anything but maybe a smear of wd40 or even oil on the plug lol. Never known any issues From it lol
In all seriousness though T.L. I know what you mean. I'm much the same way. I can't say I've ever used a torque wrench on a spark plug as access is difficult if often impossible (witness the 5/8" box end offset wrench required).
It's a matter of, as you say, feel.
And how do you know how much a "sixteenth turn" is?
A hex head has 6 sides, 60 degrees from corner to corner, or flat to flat.
1/16 of a turn is approximately 1/3 rotation from corner to corner, or flat to flat of the hex.
You can't tell me you didn't know this....
Saying it's EASY when people are asking HOW isn't an answer people can use.
Interesting comment I found on another auto board: " We used to index the plugs on small-block Chevys....it ensures that the plug`s electrode gap is facing the intake valve, giving maximum burn efficiency. You take a Sharpie and put a vertical stripe on the plug so it coincides with the gap. You then install the plug with thin shims, until you find the combination that ends up with the stripe pointed at the intake valve. It`s pretty much trial and error, takes awhile to get it just right."
And from a different guy, who lines up with above
"when Precision Tune put me through their in-house schooling, we were taught that engine and plug manufacturers coordinated to spec their threads in such a way that when the plug was torqued correctly, the electrode would be in the correct position for optimal combustion."
I stumbled on the diagram below recently (much like Skinny's post). That said, my 350 HO manual indicates 15 ft. lb. for the tapered plugs used in that engine. So with anti-seize, hand tight and snug up?
my 350 HO manual indicates 15 ft. lb. for the tapered plugs used in that engine. So with anti-seize, hand tight and snug up?
Adding a lubricant will lower friction and lower the torque spec to tighten (will turn easier). Assume ~35% less torque and you'll be in the ball park. The torque-turns method is handy when you aren't sure what revised torque value to use with a lubricant.
It's a pretty large allowable range of [dry] torque, so you've got some wriggle room. LS1tech wisdom (however wise that may be) seems to converge on about 11 lb-ft wet with 14mm tapered plug. Main thing is just don't over tighten those suckers, especially in aluminum heads.
I recommend some sort of "Anti-Galling" Material for use with Aluminum.
I would rather have something come apart slightly more easily (even unintentionally)...
Than have something seize, and not come out.
There are several good reasons why the 12,000 HP Engine in a Dragster is not Bolted into the Frame.
The equivalent of ONLY 4 Hose-Clamps hold the Engine on the Frame-Rails.
This is done for many reasons, but must importantly...
It is to be able to separate the BOMB (Engine) from the Driver in an emergency/ Crash/ Explosion.
It is nearly always better to come out too easily, than be too difficult to remove most things.
And I'll repeat, don't put anti seize on spark plug threads. Completely unnecessary, unless you have an iron headed plow truck you plan on doing zero maintenance on. If plug breakage or thread galling was a problem, I would think I would have come across it at least once in the tens of thousands of plugs I have changed. It's not cheap insurance, because it has the potential to create other issues.
Completely unnecessary, unless you have an iron headed plow truck you plan on doing zero maintenance on.
That's how you get this. Whether it would've helped this ones predicament or not will never be known.
I'm not pro nor con anti seize. I've done both. I've never had a problem with plugs I've installed. It's the ones that other animals have wrenched in there.
If you're the type of person who has a cruising car, and put's 60,000 miles on a set of plugs, then carefully put ant seize on the plug thread.
Then there me, streetstrip nitrous car. Never use anti seize....
When on the street, I use -7 plugs, then at the track I use -10 for nitrous.
Change plugs every run until I get my tune right.
My plugs aren't in the heads long enough to ever seize, lol
Plus, I never ever want anti seize, oil or anything else on the plug, I have to read the plug after the pass.
If I can't read the plug correctly, then I get holes in the piston....
09-21-2021, 08:48 AM
