spark plug - how tight

[geedubcpa]

I am a novice with mechanics - so my question is if I have replaced sparkplugs - how tight should they go back in? I am always afraid of overtightening and messing up the spark plug hole

 

[asdasc]

Re: spark plug - how tight

I have always gone finger tight (snug), plus a quarter turn. That is what my dad always taught me 35 years ago, and it works.

 

[MikDee]

Re: spark plug - how tight

I have always gone finger tight (snug), plus a quarter turn. That is what my dad always taught me 35 years ago, and it works.

This maybe okay on a spark plug with a built in metal gasket, but, Not a good idea if you have a spark plug with a beveled base, and no gasket, they're only 1/16th of a turn after hand tight. Plus, never change plugs on a hot, or warm, engine, you can strip out the threads on an aluminum head, I've had that happen on an old outboard I had (even though I was careful taking it out!), Yeah, I had to take the head off then, & have a helicoil put in.

 

[J JACKSON]

Re: spark plug - how tight

the best way it to torque them with a torque wrench Im sure someone on here has the spec but we need to know what motor your working on

 

[asdasc]

Re: spark plug - how tight

This maybe okay on a spark plug with a built in metal gasket, but, Not a good idea if you have a spark plug with a beveled base, and no gasket, they're only 1/16th of a turn after hand tight. Plus, never change plugs on a hot, or warm, engine, you can strip out the threads on an aluminum head, I've had that happen on an old outboard I had (even though I was careful taking it out!), Yeah, I had to take the head off then, & have a helicoil put in.

Good point, as far as I know, everything I work on has the metal gasket on the plugs. To be honest, I do it more by feel now. You can tell when it is tight enough, it stops turning with the strength of my wrist alone in a twist motion...not very scientific, but so far so good!

 

[MikDee]

Re: spark plug - how tight

Good point, as far as I know, everything I work on has the metal gasket on the plugs. To be honest, I do it more by feel now. You can tell when it is tight enough, it stops turning with the strength of my wrist alone in a twist motion...not very scientific, but so far so good!

True, after doing it so much, for so many years, you develop a "feel" for it, until they changed the design to the newer bevel base plugs on cars, & trucks, I'm just getting a feel for them

 

[ezeke]

Re: spark plug - how tight

I treat Champion plugs the same way asdasc does and I try to check plugs everytime I go out. I've never had a problem doing that, and never stripped a cylinder head either.

 

[crxess]

Re: spark plug - how tight

I have a head someone over muscled, heli-coiled and messed that up to. Thankfully a member hear fixed me up for cheap on a replacement.

Use the tork specs, cold motor only and don't forget the Anti-seize on the plug threads. Dissimilar metals react and will lock together over time.

 

[jonesg]

Re: spark plug - how tight

the joke used to be "tighten it til it strips then back off 1/4 turn".

 

[film495]

Re: spark plug - how tight

I actually looked up the spec for my motor the other day and it was 240 inch lbs. Much tighter than I was doing by hand, I also read that the spec affects how hot or cold the plug will be, and loose plugs will run hot because they do not transfer heat out as well that way - so, you are in theory slightly more likely to melt a plug or overheat that way, but I always just did 'em finger tight and never had an issue.

 

[kenmyfam]

Re: spark plug - how tight

I find you develop as "feel" for them after time. Do not wail on the end of the ratchet when tightening, feel from the middle.

 

[jonesg]

Re: spark plug - how tight

I use a stubby ratchet wrench, they sell em on the counter at autozone, its almost impossible to overtighten anything with it.