Spark Plug Torque Specs

tdragger

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Perhaps another set of eyes can locate the place in the service manual that specifies the amount of torque to be applied to the spark plugs when installing new ones. I've looked through both the old book and the new one and can't find it. There's not even a section on changing the plugs. I would have thought there would be a section on it.

I changed the plugs last night but I'd like to put a torque wrench to 'em before I put the tank back on.

FYI, changing the plugs was easier than I thought, especially with the 3x K&N's installed and the air ducts removed. The spark plug wrench that comes in the Triumph tool kit works very well. Based on a tip from the other site I duct taped together the spark plug wrench to a 5/8" socket and then taped to a 10" extension. No dropped plugs (and they are waaay down in there), the tool didn't become separated, easy peasy.

If someone in the know can quote the torque settings, I'd appreciate it.
 
At the risk of some serious jabbing, here are a couple of pics of the plugs removed. Those of you proficient in the black art of reading plugs, what is your analysis.

'06 Standard with 33k miles, original plugs. Left = front, right = back.
 

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I've never seen torque specs on plugs (maybe because I never looked them up), I feel for the crush washer to begin to deform on new plugs and stop there. With used plugs, I try not to crush it too much more and stop when it gets snug. It's a "feel" thing and it's better they are a little loose than too tight. Installing heli-coils after striping the threads is no fun.
 
At the risk of some serious jabbing, here are a couple of pics of the plugs removed. Those of you proficient in the black art of reading plugs, what is your analysis.

'06 Standard with 33k miles, original plugs. Left = front, right = back.
Those plugs look good to me, if it was a stock engine they would be a little leaner and lighter in color. They look a little rich, but I prefer my engines to be on the rich side when I'm floggin 'em. ;)
 
The NGK web site has this info:
Spark plug type Thread Diameter Cast Iron Cylinder Head (lb-ft.) Aluminum Clyinder Head (lb-ft.)

Flat seat type (with gasket) 18 ø mm 25.3~32.5 25.3~32.5
Flat seat type (with gasket) 14 ø mm 18.0~25.3 18.0~21.6
Flat seat type (with gasket) 12 ø mm 10.8~18.0 10.8~14.5
Flat seat type (with gasket) 10 ø mm 7.2~10.8 7.2~8.7
Flat seat type (with gasket) 8 ø mm -- 5.8~7.2
Conical seat type (without gasket) 18 ø mm 14.5~21.6 14.5~21.6
Conical seat type (without gasket) 14 ø mm 10.8~18.0 7.2~14.5


Anyone with a mic available to measure the threads on the plugs? The NGK web site doesn't provide that detail.
 
Our plugs are crush washer gasket type, if you just screw them in finger tight and give them a quarter turn or so and feel the crush washer start to deform that's tight enough. I'm just afraid that if you go by torque specs it will go past the crush distance and start tugging on the threads. The newton meters/inch torque reading will remain the same while the washer deforms, it will only begin to increase again after the washer has bottomed out. Aluminum heads scare the hell out of me and I'm always afraid of stripping the threads (I did it once long ago). But thats just my suggestion, whatever you are more comfortable with.
I do have a torque/angle meter for cylinder heads, but I never thought of using it for plugs. And I wouldn't have the balls to use a half inch torque wrench on something that delicate.
 
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