Spark Plug Torque

[MANWHORE]

I was following NGK's american website recommendation for the torque for a 14 mm thread (that's what our plugs are). The site said 18-21 foot pounds.

Normally, I just hand tighten it, then go another 2/3 turns. I normally just use a short 3/8 drive ratchet, so it's pretty hard to overtorque it, because you can't put my torque on it anyways.

Today, I was borrowing my friend's torque wrench, so I thought i'd torque them. Mind you, that wrench, is one of those $10 ones from supercheap auto, so I don't trust the reading. It is a 1/2" drive one like 30 cm long, so it'd be possible to easily overtorque it.

Anyways, I kept turning until about 1 full revolution past hand tight.

1. for those of you who have also used a torque wrench, did you also find that to get the correct torque, you had to go almost 1 full revolution? or have I f**ked it and tightened it too much?

3. For those of you who have engine building experience, or those of you who know about how far the piston comes up, do you think that the spark plug will be sitting too low down in the combustion chamber, and will the piston touch it?

Edited April 1, 2007 by MANWHORE

[dead32]

1. some torque settings actualy use a degree wheel. spec e.g tighten to 70n then 90degree

2. it will not even go close to touching

[Simon-S14]

plugs are done by feel... with a spark plug socket + extention bar thread them in finger tight, then use the ratchet to tighten them 1 full revolution, never any more.

best to err on the too loose side then too tight.

and no, having the plugs too tight will not make the plug come in contact with the piston, it will on the other hand give you drama;'s when it comes to take the plug out with it possibly snapping the ceramic section off in the head.

[Lunatikk]

As Simon said it's mostly a "feel" thing with plugs & be v-careful with over-tightening 'cos you run the real risk, esp with an alloy head, of pulling the thread & whilst you can sometimes do a dodgy repair in-car it's usually a head off proposition to fix properly

[SECURITY]

^^ what he said.

theres no way it will hit.

this is a pic of the head during my build. you can see how far up the spark plug sits.

[MANWHORE]

thanks joe. yuuummm that's some nice machining there