Topic: Spark Plug Torque?

[DaveInTexas]

I am a bit more comfortable using a t wrench than the manual's til snug then 1/4 to 1/2 turn.
Does anyone have an accepted torque value for these? 
I tried 10lbs and it needed more so 15-20ft-lbs?

[merc2dogs]

I don't use a torque wrench on them, just a cheap plug wrench, for a two stroke snowmobile or chainsaw similar to the oem type, use a craftsman 8" shaft 1/4 inch flat screwdriver for the handle and just snug it till I get a slight bow in the screwdriver, always use the same screwdriver
  I don't recall ever having seen a torque spec for a spark plug, most plug maker recomend installation depending on type of seal the plug has, tapered seat or metal gasket, and then it's 1/4 turn after contact for taper seat, and half turn for gasket.

  wackiest torque specs I've seen were for a VW rabbit head bolts, " torque in 3 steps to 70pounds, then 3/4 turn more"

ken. 
 

[kghost]

DO NOT over tighten them.

They are tapered seat. metal gasket plugs in aircraft are torques to around 25 ft/lb

With tapered seat plugs a 1/4 turn after snug is sufficient.

DO use antiseize on the plugs. So much easier and safer on your head next time you wanna get them out.

[dusterdude]

ken,your vw head bolts are called torque to yield.they are only good for one use,then you replace them.almost all manufacturers use them now.

[mick750F]

 Torque value from a '78 factory manual....8.7-13.7 ft.-lbs.

Mike

[hcritz]

DusterDude is correct...most new engines use "turn of the nut" for torquing...It actually pulls the bolt into yield (stretches it).
This eliminates the need for re torquing after the engine has run...but most require replacement if they are removed...
I've seen several thoughts on Anti-seize compound on plug threads...some say it raises the plug temp. by insulating it from the head...I find that a bit hard to believe...I have used it for years on Aircooled engines and can't see that it causes the plugs to appear to have been run hot. Sure beats ruining the threads in the the head...Most do recommend that you pull the plugs with the engine cold or at least cool...

[dusterdude]

whoo hoo,im right,you hear that oz man(you know who you are),whoo hoo.

[Bob Wessner]

whoo hoo,im right,

DD, you are entitled to gloat.. since it happens so infrequently. 

[dusterdude]

whoo hoo,im right,

DD, you are entitled to gloat.. since it happens so infrequently. 

yea,aint that the truth.

[merc2dogs]

 Yeah know they're torque to yeild, it's just that every other engine I've worked on provided a definate value,  not an imprecise 'guess'
  Done far too many tty head bolts and still hate the things. my engines are always changed over to 'real' bolts.

ken.

[DaveInTexas]

Torque value from a '78 factory manual....8.7-13.7 ft.-lbs.

Thanks Miike, that is valuable objective info.
And you know what, that is what felt right!

Can I assume that engine uses 12mm plugs as well?