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Discussion Starter #1
I have a cheap 25-250 Lb.inch Sears wrench, clicker type.

When set to 7 Ft Lbs for the camshaft journal bolts it felt to me like the torque applied was too low; so I checked it with a fisherman's scale, and I rechecked it using a measured weight (sugar and salt measured on a digital kitchen scale). Fortunately, the lever arm on the wrench is 12". In order to get 84 inch-Lbs one has to set the wrench at about 112 in-Lb.

The actual torque applied at the 84 Lb-in setting was less than half the setting value.

The interesting thing is that I had deliberately over-torqued the journal bolts, since I doubted the torque wrench, and all but one journal bolt clicked "ok" on the corrected wrench.
 

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I use a similar wrench and the conversion chart says 12 inch pound equals a foot pound. So do you think it's that these wrenches are just that inaccurate? If they are off by that much, it would seem they are worthless.
 

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Torque wrenches like a lot of psusedo precision tools are supposed to be calibrated ocasionally.
Just where one sends a Sear wrench I dunno. Snap-On might have a depot that one sends their stuff to. I think having an extension on the wrench can change the true value too.
 

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Discussion Starter #4
so I ordered a digital wrench online (Amazom)

Digital technology is inherently easier to get precision with as they use strain gages (or similar) - and we can reader user reviews before we buy.

No way do I want to strip a thread in an aluminum engine.

I opened an Amazon credit card account and got $50 off - not so bad.

Here is my ordered item:
ACDelco ARM601-3 3/8-Inch Digital Torque Wrench 2-37 ft-lbs
 

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I have a friend who is a machinist, and he laughs at me with my anal torque wrenching of every single little nut and bolt.

He waffled on about different metal types (something to do with a the "spring" a metal has), thread types, friction, etc, etc, etc, and basically said even with a Snap-On it's an imprecise science.
 

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Discussion Starter #6
its not imprecise

I have a friend who is a machinist, and he laughs at me with my anal torque wrenching of every single little nut and bolt.

He waffled on about different metal types (something to do with a the "spring" a metal has), thread types, friction, etc, etc, etc, and basically said even with a Snap-On it's an imprecise science.
its not imprecise - but it is quite variable due condition of both threads and lubrication of threads

what most folks don't know is that most load transfer happens in the first few engaged threads, so a deep thread does not mean humongous load capacity - though it may help with one strong metal (steel bolt) and one weak metal (aluminum)
 

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My low-range Craftsman clicker was innaccurate as well, as was my med-range Kobalt (Lowes) clicker. I replaced them with electronic wrenches from GearWrench (low-range 1/4"), and Eastwood (med-range 3/8", high-range 1/2"). I also considered higher-end clickers, but these electronic wrenches were the best bang for the buck for me. You can find these on Ebay and Amazon, probably at competitive pricing. You can sure spend a lot of money on torque wrenches.
 

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The torque wrenches like the Snap-On that have a collar for tightening to dial in the click point are suppose to be stored at the Zero setting too.
I have a Sears wrench with the needle that point to a value on the handle. If it's close to right it's good enough for me. Lots of fellers are so accurate anal they bugger fasteners all the time. Good mechanics!
 

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Discussion Starter #9
Electronic torque wrench update

the 3/8" AC Delco unit is working fine, I also bought a 1/2" unit from Eastman. Had I less urgency and less frugality I should have bought both from the same vendor so that I don't have to remember two different methods of setting torque!

Actually - I typed up the instructions for each in 14 pt Arial and taped them to the cupboard doors above my workbench (so I get it wrong less often).
 

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See if you can remove an end cap on the handle of your torque wrench and find an adjuster under there. Adjust the torque wrench for the middle of the scale, then test it to see how close it is at 10% and 90% of the scale. It probably only needs to be professionally calibrated if you're overhauling a gas turbine or something like that.

Yes, the torque spec depends on the thread pitch, the material of the bolt and the base metal, the surface finish of the threads, and the type of lubrication if any--all these effect the friction of the threads which absorbs much of the torque. You are right to torque lots of things until you acquire the feel for tightening. I've know some who try to twist off every bolt they tighten and others who have no idea that they aren't nearly tight enough. I've seen torque specs for things like medium sized diesel head bolts that called for two men on a six foot bar....
 

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40 years ago in high school shop class I used a torque wrench when rebuilding the engine of the instructor's car (mid-sixties Chevy Nova). Wouldn't turn over when we got it back in the car - embarrassing. :confused:
I forget what he did after that because I wasn't involved. He did pass me though.
Since then I've never used a torque wrench - not really because of that, it just hasn't seemed necessary. A good feel for 'snug' works for me - along with common sense when working with aluminum. As a rough check I'll sometimes consider the length of the wrench/breaker bar and apply a guesstimate of the force I need for a given torque. It's worked so far.
Of course I haven't been deep into an engine since high school.
 

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As an enginerd, I have a hard time with the inexact matter of tightening important fastners by feel, so I use a torque wrench, but very carefully. Around two years ago I replaced my clickers with electronic models from GearWrench (low) and Eastwood (medium and high). They are more accurate, but I have to relearn the Eastwood menu system nearly every time.
 
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