torque wrench question

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Sniper82

Lifer
Feb 6, 2000
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Spark plugs call for 108 in lb, I call around for a in pound torque wrench and no one in my area has them. One guy told me to just multiply 108 by 12 and and it would be 9 ft lb on the wrench I got.

Is it ok to do this?
 

BW86

Lifer
Jul 20, 2004
13,114
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I usually just tighten them with a regular socket wrench + extension until they are tight... Never felt the need to use a torque wrench on spark plugs.
 

fleabag

Banned
Oct 1, 2007
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Originally posted by: Sniper82
Spark plugs call for 108 in lb, I call around for a in pound torque wrench and no one in my area has them. One guy told me to just multiply 108 by 12 and and it would be 9 ft lb on the wrench I got.

Is it ok to do this?

What is your ft-lb wrench out of? Torque wrenches aren't accurate on the bottom 20% of their range. So a 100ft-lb torque wrench is useless if you want to torque something to 19ft-lbs.
 

woodie1

Diamond Member
Mar 7, 2000
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Originally posted by: Sniper82
Spark plugs call for 108 in lb, I call around for a in pound torque wrench and no one in my area has them. One guy told me to just multiply 108 by 12 and and it would be 9 ft lb on the wrench I got.

Is it ok to do this?

You would divide by 12 to convert from inches to feet which it seems you or someone did as 9 is correct..
 

NutBucket

Lifer
Aug 30, 2000
27,119
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Originally posted by: fleabag
Originally posted by: Sniper82
Spark plugs call for 108 in lb, I call around for a in pound torque wrench and no one in my area has them. One guy told me to just multiply 108 by 12 and and it would be 9 ft lb on the wrench I got.

Is it ok to do this?

What is your ft-lb wrench out of? Torque wrenches aren't accurate on the bottom 20% of their range. So a 100ft-lb torque wrench is useless if you want to torque something to 19ft-lbs.
Ask me how I know this.....
 

fleabag

Banned
Oct 1, 2007
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Originally posted by: NutBucket
Originally posted by: fleabag
Originally posted by: Sniper82
Spark plugs call for 108 in lb, I call around for a in pound torque wrench and no one in my area has them. One guy told me to just multiply 108 by 12 and and it would be 9 ft lb on the wrench I got.

Is it ok to do this?

What is your ft-lb wrench out of? Torque wrenches aren't accurate on the bottom 20% of their range. So a 100ft-lb torque wrench is useless if you want to torque something to 19ft-lbs.
Ask me how I know this.....

what??
 

bruceb

Diamond Member
Aug 20, 2004
8,874
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9 Ft/Lbs is indeed the correct value for 108 Inch Lbs ... problem is most torque wrenches in 3/8 drive size are not that accurate under 10 to 12 Ft/Lbs ... that is why they suggest the use of a wrench in Inch Lbs for values up to about 15 Ft / Lbs ... This holds true especially if the range of your Torque wrench is large, say 5 to 75 Ft / Lbs .. If on the other hand your Torque wrench is designed for say 5 to 30 Ft/Lbs
then it likely would be pretty accurate at 9 Ft/Lbs or so. On most cars, you can snug the spark plug until it seats by hand. Then go 1/4 to 1/2 turn additional. That would be safe in most cases. And if the engine is aluminum heads, antisieze on the thread (not much) is a good idea (also good on iron heads, but not as critical on them)
 

NutBucket

Lifer
Aug 30, 2000
27,119
613
126
Originally posted by: fleabag
Originally posted by: NutBucket
Originally posted by: fleabag
Torque wrenches aren't accurate on the bottom 20% of their range. So a 100ft-lb torque wrench is useless if you want to torque something to 19ft-lbs.
Ask me how I know this.....

what??
I mean I've run into this problem and snapped a couple bolts because of it. Of course, I should have known I was applying far more that 10 ft-lbs;)
 

zylander

Platinum Member
Aug 25, 2002
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Originally posted by: BW86
I usually just tighten them with a regular socket wrench + extension until they are tight... Never felt the need to use a torque wrench on spark plugs.

This.
 

Kaervak

Diamond Member
Jul 18, 2001
8,460
2
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Originally posted by: zylander
Originally posted by: BW86
I usually just tighten them with a regular socket wrench + extension until they are tight... Never felt the need to use a torque wrench on spark plugs.

This.

Same here, never had an issue. I recommend putting some anti-seize on the plug threads. It's not absolutely necessary, but it makes life easier later on.
 

Colt45

Lifer
Apr 18, 2001
19,720
1
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for wussy stuff like that, I just kinda.. limpwrist it with a guess thrown in.. seems plenty accurate.
 

LTC8K6

Lifer
Mar 10, 2004
28,520
1,575
126
I used to calibrate torque wrenches. It was very easy to slip up and damage the 5 foot pound torque cell on the machine...
 
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