Hi all:
A few weeks back, all of you were very helpful with tips on spark plug replacement for my 95 Maxima. The job went very well and all 6 plugs are now replaced.
Now to the question... NGK says that in lieu of a torque wrench, the "torque angle" method can be used. For the plug I used, they say 1/2 to 2/3 of a turn will produce their recommended torque of 18-21.6 lb ft of torque. My factory service manual calls for 14-22 lb ft of torque so I decided 18 lb ft would be a good midpoint selection for torque. For this job, because I didn't want to take any chances with my aluminum heads and needed one anyway, I bought a new Precision Tools split beam 8-50 lb ft torque wrench. They are apparently one of the best manufacturers out there - building them from scratch in the USA since 1938!
Since I'm a naturally curious person, I wanted to compare the amount of turn at the point I reached 18 lb ft. It wasn't very straightforward because of obstructions in the engine bay I had to remount the torque wrench/extension-socket upwards of 3-4 times so some of the summations I reached for the rear three plugs probably aren't exact - for instance 3 approximately 1/4 turns plus a bit more. But for the front three, I was able to reach 18 lb ft in one continuous arc. During the turn(s) I was careful to keep the long extension centered in the spark plug hole with my fingers of my left hand so as not to crack the insulator and being mindful not to apply any counter-torque - just keep it centered. I noted that to reach 18 lb ft, it took about 270 to 300 degrees of turn compared to NGK's "torque angle" value of 180 to 240 degrees of turn. And, what makes it even more interesting is if the NGK torque angle method produces between 18 and 21.6 lb ft of torque, one would presume that 18 would be reached at the 180 degree mark, and 21.6 reached at 240 degrees, and I was 270+ for 18 on the torque wrench. Note no antiseize or crow feet extenders were used which would have altered things
I asked NGK, and like I suspected, they said to basically defer to the torque wrench as long as I was confident it was calibrated properly which I would have no reason to doubt as it was brand new. But I'm still left mystified as to how they can tell folks they can rely on their torque angle method when, at least in my case, it didn't seem to jive at all.
Has anyone done a similar experiment? Thoughts on my observations?
A few weeks back, all of you were very helpful with tips on spark plug replacement for my 95 Maxima. The job went very well and all 6 plugs are now replaced.
Now to the question... NGK says that in lieu of a torque wrench, the "torque angle" method can be used. For the plug I used, they say 1/2 to 2/3 of a turn will produce their recommended torque of 18-21.6 lb ft of torque. My factory service manual calls for 14-22 lb ft of torque so I decided 18 lb ft would be a good midpoint selection for torque. For this job, because I didn't want to take any chances with my aluminum heads and needed one anyway, I bought a new Precision Tools split beam 8-50 lb ft torque wrench. They are apparently one of the best manufacturers out there - building them from scratch in the USA since 1938!
Since I'm a naturally curious person, I wanted to compare the amount of turn at the point I reached 18 lb ft. It wasn't very straightforward because of obstructions in the engine bay I had to remount the torque wrench/extension-socket upwards of 3-4 times so some of the summations I reached for the rear three plugs probably aren't exact - for instance 3 approximately 1/4 turns plus a bit more. But for the front three, I was able to reach 18 lb ft in one continuous arc. During the turn(s) I was careful to keep the long extension centered in the spark plug hole with my fingers of my left hand so as not to crack the insulator and being mindful not to apply any counter-torque - just keep it centered. I noted that to reach 18 lb ft, it took about 270 to 300 degrees of turn compared to NGK's "torque angle" value of 180 to 240 degrees of turn. And, what makes it even more interesting is if the NGK torque angle method produces between 18 and 21.6 lb ft of torque, one would presume that 18 would be reached at the 180 degree mark, and 21.6 reached at 240 degrees, and I was 270+ for 18 on the torque wrench. Note no antiseize or crow feet extenders were used which would have altered things
I asked NGK, and like I suspected, they said to basically defer to the torque wrench as long as I was confident it was calibrated properly which I would have no reason to doubt as it was brand new. But I'm still left mystified as to how they can tell folks they can rely on their torque angle method when, at least in my case, it didn't seem to jive at all.
Has anyone done a similar experiment? Thoughts on my observations?