torque wrench and piston question

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63dartman

63dartman

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I have a fairly cheap clicker type wrench (bought at harbor freight) Will this be good enough for rebuilding? What is a good wrench to use if not? Also are the kb107 pistons a good choice for a 360 performance rebuild, using standard j heads and a cam with these specs>>>>>>>>>>>>>>>> Advertised Duration IN/EX: 256/262
Duration @ .050 IN/EX: 213/220
Gross Valve Lift IN/EX: .454"/.475"
LSA / ICL: 112/108
Valve Lash IN/EX: Hyd/Hyd
RPM Range: 1000-5500


The only concern I have is our elevation here is 5000ft. I know I will not run as good as you guys down low but, will it cause issues?
 
I'm no real expert on cams, but that's fairly mild so I think it would be ok where you are. I have a Harbor Freight torque wrench and it has proven to be more reliable than the two Craftsman wrenches my sons have.
 
Jim Lusk said:
I'm no real expert on cams, but that's fairly mild so I think it would be ok where you are. I have a Harbor Freight torque wrench and it has proven to be more reliable than the two Craftsman wrenches my sons have.
Click to expand...


can i asked how you proved that? ive tested my craftsmen to my friends snap-on and it was the same :salute:
 
Both Craftsman torque wrenches have become loose in the handle. One was sent back for repair. The other just happened recently so it hasn't gone back, but it's out of warranty, unlike the other.
 
FWIW,

In the scheme of things using a torque wrench is the least accurate method to tighten a threaded fastener (tightening by feel being the only less accurate way). Bolt stretch, then strain guages followed by torque to yield are the most accurate way.

That being said the best thing a torque wrench can do is be repeatable since the actual clamping force in the joint is going to vary by as much as 40% due to friction variations. On a click type wrench the best way to ensure it's repeatability is to back it down to zero after each use.
 
I bought a Snap-On click type uver 25 yrs ago. Taken good care of it and
it still is very acurate. I'd say spend the money and get a good one. You
won't have any complaints. :tool:
 
If you do use KB pistons follow their instructions about ring end gap TO THE LETTER! Very important. It may seem strange compared to cast or forged pistons, but it is the way to go.

don
 
And if it ever gets dropped to a hard surface, replace or send it out for recalibration. The clicker types can be the worst in terms of accuracy..the dial types are the most accurate by my research. But I have a Snap On clicker too...lol. never leave it set to any value other than 0 when storing it..always back it off if you're not using at that second...
 
Price and quality do go hand in hand, but for the one time or occasional
project that requires a torque wrench a rent-all store might be your best bet.
The cheap clicker type wrenches might not be too accurate.
Toolmanmike
 
Why would anyone trust a multiple-thousand dollar engine build to a $39.99 torque wrench? You spend good money to buy the best parts you can afford to put in the engine, then use a cheapo torque wrench to assemble it? Discount tool vendors are a godsend for certain tools, but why risk your engine to a suspect quality torque wrench. You should never use a torque wrench whose quality or care is suspect. Rent one? Are you kidding? Get your own. Buy one from a reputable tool dealer and take care of it. Keep it zeroed when not in use, and never use it to loosen fasteners! Your torque wrench... Your engine's life may depend on it!
 
torquehouse said:
Why would anyone trust a multiple-thousand dollar engine build to a $39.99 torque wrench? You spend good money to buy the best parts you can afford to put in the engine, then use a cheapo torque wrench to assemble it? Discount tool vendors are a godsend for certain tools, but why risk your engine to a suspect quality torque wrench. You should never use a torque wrench whose quality or care is suspect. Rent one? Are you kidding? Get your own. Buy one from a reputable tool dealer and take care of it. Keep it zeroed when not in use, and never use it to loosen fasteners! Your torque wrench... Your engine's life may depend on it!
Click to expand...
I have built over 20 or more engines, half of those being performance type, I have yet to have a problem with my $39.99 t/wrench. I do take the same care of this tool as if I had $300.00 invested in it. Now i can see where the torque to yeild bolts or the stretch method would be more accurate, just as never reusing critical fastners. The bottom line is, TORQUE THOSE FASTNERS, even if all you have is a $39.99 wrench. Just my opinion.
 
torquehouse said:
Why would anyone trust a multiple-thousand dollar engine build to a $39.99 torque wrench?
Click to expand...

Because it doesn't make any difference. As I stated in my previous post the variation in clamping force generated when tightening a fastener to a given torque will vary up to 40%. So a $100 troque wrench with a 1% accuracy compared to a $39 wrench with a 2% accuracy is not going to matter.

As long as the force generated by the bolts is greater than the forces trying to seperate (cylinder pressure and thermal expansion) the block and head you are good to go regardless of what the torque on the bolts are. When the torque specs are developed for a non torque to yield fastener they are chosen based on inaccuracies of using a torque wrench.

If you want the most accurate wrench go get a $29 beam type wrench, they are going to be as accurate or better than any of the click type wrenches.

Making sure the threads in the head and on the fasteners are burr free, making sure the head of the bolt and it's mating surface are burr free & flat and using a consistent amount of lubricant is much much much more important than the the actual wrench you are using.

BTW, I do speak from some level of expertise, my first job out of college was developing the torquing procedures for the assembly of the jet engines used in the F14 and F15 fighters.
 
dgc333 said:
Because it doesn't make any difference. As I stated in my previous post the variation in clamping force generated when tightening a fastener to a given torque will vary up to 40%. So a $100 troque wrench with a 1% accuracy compared to a $39 wrench with a 2% accuracy is not going to matter.

As long as the force generated by the bolts is greater than the forces trying to seperate (cylinder pressure and thermal expansion) the block and head you are good to go regardless of what the torque on the bolts are. When the torque specs are developed for a non torque to yield fastener they are chosen based on inaccuracies of using a torque wrench.

If you want the most accurate wrench go get a $29 beam type wrench, they are going to be as accurate or better than any of the click type wrenches.

Making sure the threads in the head and on the fasteners are burr free, making sure the head of the bolt and it's mating surface are burr free & flat and using a consistent amount of lubricant is much much much more important than the the actual wrench you are using.

BTW, I do speak from some level of expertise, my first job out of college was developing the torquing procedures for the assembly of the jet engines used in the F14 and F15 fighters.
Click to expand...
Yea, what he said!
 
Thanks for all the great comments, So in the end.......Since I have not kept my torque wrench at zero when not in use. I am going to get a "quality" built wrench and take care of it like my engines life depended on it. (since it does) :) More importantly, I will pay close attention to "how" the bolts thread into the the parts. Thanks again for all the great comments.
 
Yea I agree also, that there are a lot of mistakes made when torquing fasteners and my biggest pet peave is technique. You don't use the torque wrench like a ordinary rachet. The wrench is only accurate if the operator is using a "slow progressively higher" pull to the point of the click and no further. You young wrenches will love this because it's a great way to build up your biceps but us old guys are sick of it because of the tendonitis that long term wrench pulling causes. I by the way show customers how to rebuild gas turbines, steam turbines and centrifugal gas compressor and you ain't seen nothing until you run a hydraulic torque wrench that'll take a big assed nut to 50,000 foot pounds. Thankfully stud torqueing has progressed from the middle ages so that today most of the large studs are actually stretched, to the proper dimension, using a hydraulic stud tensioner and then simply run the nut down by hand and release the hydraulic pressure. This device actually allows you to monitor and measure the stud stretch in thousands of an inch. Neat eh.
 
That sounds sooo cool... the four biggest things on using a torque wrench and building reliably...
1. Take care of your tools. Clickers should be released before puttin git down. Every time. And "put down" does not every mean "drop". If it hit sthe floor, or slips and doesnt get placed down, have it calibrated. A good torque wrench will last a very long time. Beam types most accurrate, and hardest to use(DAMHIK). Dial types are very close to beam types for accuracy, and just as hard to use. Clickers are the last.
2. If it's got threads in it (any hole, iron, aluminum without inserts..) use a bottoming tap during the block washing process. In every hole..heads and mains are important, but if you've ever tried to use the tips of 2 fingers threading in the lower bellhousing bolts on a Dart, you'll appreciate how much easier the bolts go in...lol). Tap the holes, then blow them out with solvent and compressed air. All bolts being reused shoule also be run thru a die to make sure the threads arent buggered. Head bolts, and main bolts especially. The tumblers some shops use to clean them can roll threads slightly, so the torque indicated is not correct.
3. Use the correct lubricant on the fastener and go in proper sequence. ARPs use ARP moly lube. Factory fasteners use 30W oil. The specs vary for different lubes. Most websites have the info if you know the part numbers of the fasteners used.
4. Apply torque in steps. You will get 1/2-3/4 of a turn more on a head bolt going in 3 steps, and ending with the same load. I know many with seeping steel headgaskets that dont do the steps...Smooth and steady, no hard jerking the torque wrench.
Notes: Aluminum heads should always be re-torqued after they have been run a few times. most times you'll find a few that are below torque value after some heat cycles. Studs are meant to be threaded by hand. You dont need to crank them in tight with vice grips or the allen wrench. finger tight, then torque the nuts, and dont forget to use the right lube between any nuts, bolts heads, and washers too. Not just the threads. Keep a written record of when you tighten every fastener. A note jotted down with greasy fingers will give you peice of mind if you need to stop and then come back to it.
 
Great info moper, I will be referring back to this when I start assembly on my engine. Thanks again for the replies.
 
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