Note to self:

[Tom S]

^^^

[Double0-12]

If performing an engine swap and you decide to use a shop manual, know the difference between lbs./ft. & lbs./in. Also, spark plug threads shear off at 92 lbs./in.

[Tom S]

Originally Posted by Double0-12

Also, spark plug threads shear off at 92 lbs./in.

92 lbs./in is only 7.667 lbs./ft. I see the torque spec for 2 different bike's spark plugs @ 12.5 lbs./ft., equal to ~95.2 lbs./in. I’m sure I have exceeded that many times.
If you stripped threads @ 92 lbs./in something else was wrong.

[Double0-12]

Originally Posted by Tom S

92 lbs./in is only 7.667 lbs./ft. I see the torque spec for 2 different bike's spark plugs @ 12.5 lbs./ft., equal to ~95.2 lbs./in. I’m sure I have exceeded that many times.
If you stripped threads @ 92 lbs./in something else was wrong.

See, I still don't know what I'm doing. I could probably add a few pages to this thread on my own.

[disston]

I don't use a torque wrench on spark plugs. I run them snug then add about 1/16 of a turn more. This is not tight. They don't have to be any tighter.

[troidus]

Originally Posted by disston

I don't use a torque wrench on spark plugs. I run them snug then add about 1/16 of a turn more. This is not tight. They don't have to be any tighter.

Depends on if they're gasketed or tapered plugs.

[Forde]

Originally Posted by Tom S

92 lbs./in is only 7.667 lbs./ft. I see the torque spec for 2 different bike's spark plugs @ 12.5 lbs./ft., equal to ~95.2 lbs./in. I’m sure I have exceeded that many times.
If you stripped threads @ 92 lbs./in something else was wrong.

maybe the manual said lb/in and he torqued to 92 lb/ft cos he claims he mixed them up

[catweasel67]

Originally Posted by Tom S

92 lbs./in is only 7.667 lbs./ft. I see the torque spec for 2 different bike's spark plugs @ 12.5 lbs./ft., equal to ~95.2 lbs./in. I’m sure I have exceeded that many times.
If you stripped threads @ 92 lbs./in something else was wrong.

according to my brain, which is pretty feeble..

92.2 PSI = 13248 PSF...

[Tom S]

Originally Posted by catweasel67

according to my brain, which is pretty feeble..92.2 PSI = 13248 PSF...

We are not talking about pressure, we are talking about torque. PSI is pressure, pounds per square inch.
My numbers for torque are correct.
Your numbers for PSI to PSF are very close, 13248 PSF = 92.00 PSI. Divide 13276.8 by 144. Equals 92.20 PSI
I sure hope nobody would mix up inch pounds with foot pounds & torque something to 92 foot pounds instead of 92 inch pounds!

[MiteyF]

Originally Posted by MsLizVt

Hi everyone!

Hope you don't mind me stepping in here for a moment.

The unfortunate event is that Double0-12 truly over torqued his spark plug, so much so, that he broke it off inside the head. That's a LOT of torque. His point, about recognizing the difference between inch pounds and foot pounds is valid.

As Tom S. says, at 12.5 foot pounds the spark plugs shouldn't break like that.

However, Forde's evaluation is that Double0-12 meant he used a foot pound gauge set to 92 pounds to torque his spark plug. That makes sense, if you ask me.

The amount of torque in inch pounds using a foot pound gauge would be 1,104 inch pounds of torque that was put on the spark plug, with the gauge set at 92 pounds. (92 pounds/foot times 12 inches per foot = 1,104 pounds per inch.)

Catweasel you're onto something, but it's not torque. I believe you're calculating pounds per square inch and pounds per square foot. Your calculation was 92 pounds per square inch times 144 square inches in a foot, yielding 13,248. Yes?

It probably wouldn't be much more than a lot of confusing verbiage if I went into the mathematics of the calculation of torque. My expectation is by the time I start spewing terms like vectors, rotational forces, derivatives,and angular momentum everyone's eyes would glaze over.

The quick description is torque wrenches are calibrated to measure the force necessary to turn a bolt/nut a certain amount based on the wrenches calibration values. (inch pounds, foot pounds, newton meters)

The simple answer is Double0-12 used the wrong torque wrench, and he knows it. Yes Double0-12?

Has this has been helpful.

Enjoy,

Liz

While you seem to have it nearly nuts on... you're throwing out math terms that have no place here. This stuff is simple algebra, no derivatives necessary. And we're TORQUING spark plugs here, no rotational velocity to speak of, thus angular momentum means nothing here. Plus, as we're already talking about calibrated torque wrenches, so unless we're designing and manufacturing the wrench itself, vectors are a non issue.

Thanks for the attempt at help, but there's no need to prove you're good at math. We believe you.

[Jayrod1318]

Originally Posted by R_Rick

Note to self:

Putting the heat shrink tube on the wire before soldering the final splice saves from having to solder twice.

You should have told me that before the 15th time I've done that.

[Double0-12]

My torque wrench and I caused enough trouble to the bike, we didn't mean to start any drama here! This was the first time I had ever used a torque wrench I believe. Since I was doing an engine swap I had the wrench for the engine mounting bolts. For some dumb reason decided to torque the plugs because the wrench was there. Usually I just get them finger tight, then about 1.5 rotations or so more. I can find the wrench and manual to put this to rest a little later if need be. In any case my attempt to save $600+ dollars on a shop doing the swap cost me almost that anyway in having them get the threads out of the block. I thought I had tried everything, but after reading this thread I see I could have tried a lot more!

[MsLizVt]

Originally Posted by MiteyF

While you seem to have it nearly nuts on... you're throwing out math terms that have no place here. This stuff is simple algebra, no derivatives necessary. And we're TORQUING spark plugs here, no rotational velocity to speak of, thus angular momentum means nothing here. Plus, as we're already talking about calibrated torque wrenches, so unless we're designing and manufacturing the wrench itself, vectors are a non issue.

Thanks for the attempt at help, but there's no need to prove you're good at math. We believe you.

Originally Posted by Double0-12

My torque wrench and I caused enough trouble to the bike, we didn't mean to start any drama here! This was the first time I had ever used a torque wrench I believe. Since I was doing an engine swap I had the wrench for the engine mounting bolts. For some dumb reason decided to torque the plugs because the wrench was there. Usually I just get them finger tight, then about 1.5 rotations or so more. I can find the wrench and manual to put this to rest a little later if need be. In any case my attempt to save $600+ dollars on a shop doing the swap cost me almost that anyway in having them get the threads out of the block. I thought I had tried everything, but after reading this thread I see I could have tried a lot more!

Double0-12, et al.

I apologize. I was just trying to be helpful. If my post was aloof, it wasn't meant to be. It was just meant to be helpful.

None the less, I nuked it to not perpetuate the drama.

Sorry,



Liz

[MrBob]

Originally Posted by Double0-12

My torque wrench and I caused enough trouble to the bike, we didn't mean to start any drama here! This was the first time I had ever used a torque wrench I believe. Since I was doing an engine swap I had the wrench for the engine mounting bolts. For some dumb reason decided to torque the plugs because the wrench was there. Usually I just get them finger tight, then about 1.5 rotations or so more. I can find the wrench and manual to put this to rest a little later if need be. In any case my attempt to save $600+ dollars on a shop doing the swap cost me almost that anyway in having them get the threads out of the block. I thought I had tried everything, but after reading this thread I see I could have tried a lot more!

You're perfectly justified in using a torque wrench on your plugs. Sounds like you mis-read your values, but, it happens. I seem to remember a Mars-bound vehicle going astray because engineers confused metric with non metric measurements, and they were rocket scientists.
Eventually, your brain remembers what the correct torque feels like and it becomes automatic. Using a torque wrench is the sign of a careful mechanic and someone who recognizes that these values were usually developed by a department full of really smart people.
People can make any endeavor more complicated than it needs to be and I see no shortage of irrelevant B.S. in this thread. Use your manual, take your time, ask questions when you need to, thing twice when you're unsure, have fun.

[ER70S-2]

Originally Posted by MsLizVt

Double0-12, et al.

I apologize. I was just trying to be helpful. If my post was aloof, it wasn't meant to be. It was just meant to be helpful.

None the less, I nuked it to not perpetuate the drama.

Sorry,

Liz

Hiya Liz:
This is ADVrider. Don't let the occassional dick-head scare you away. I learn lots here, including your post.