Y'all's Thoughts on Torquing Bolts Correctly, Please

A friend and I have had this argument for years...

Let's say we're torquing the heads on a SBC, and the specified final torque is 65 Ft/Lbs.

Here's the disagreement- he favors once around the pattern at 65. I go around, at the final value, 3 times- basically until the torque wrench clicks without turning the bolt any further. He thinks my way is over-torquing.

I'm real interested in y'all's takes on this. [Of course, if he wins, I'll never tell him about this survey.]

joe

Umm. "Technically", if the bolt achieved 65 lb-ft, then it shouldn't rotate anymore and you are both correct. Whether he does a single pass, you do 3 passes, and someone else with OCD does 6 passes, it shouldn't matter.

In practice, however, everyone that has used a torque wrench has had at least one faster rotate a tiny bit more at some point, somewhere, some job when going around a second (or third?) pass...and the reason is a bit more technical than one would think.

I believe in more than one pass. If is 65 ft lbs, then I do a pass at 50-55 ft lbs and then a second pass at the same to know that I am at the same point with all of them. Then I would do two passes at 65 ft lbs. I also use a digital torque wrench and if not handy I would use a click type. Beam style wrenches are not the way to go at all.

Also, I prep all threaded holes, in the block or in a nut, with a chase and I do not lube threads.

homesick said:

Let's say we're torquing the heads on a SBC, and the specified final torque is 65 Ft/Lb.
Here's the disagreement: he favors once around the pattern at 65Ft/Lb.
I go around, at the final value, 3 times - basically until the torque wrench clicks without turning the bolt any further.
He thinks my way is over-torquing.

Click to expand...

Assuming you're talking about one final pass vs three final passes,
and assuming all three passes are truly indiscernible from one another,
it SHOULD make no difference.

More important is all the other stuff prior to the final pass(es).

Long ago, I read somewhere that Ferrari has an unusually elaborate torquing procedure for engine parts,
which seems to make sense given that many tend to be able to rev over 7000RpM.

Ok, I didn't say so specifically [my error] but we're assuming that not all bolts have reached 65 after the first pass. If one pass always did it, I'd've never started making more passes.

Does this change anything for anyone?

joe

OR VietVet said:

I believe in more than one pass. If is 65 ft lbs, then I do a pass at 50-55 ft lbs and then a second pass at the same to know that I am at the same point with all of them. Then I would do two passes at 65 ft lbs. I also use a digital torque wrench and if not handy I would use a click type. Beam style wrenches are not the way to go at all.

Also, I prep all threaded holes, in the block or in a nut, with a chase and I do not lube threads.

Click to expand...

LOL, this answer is another reason I wish you lived close enough to be my mechanic.

I used clicking torque wrenches as a stand-in for all types. I did not know that beam wrenches should be avoided. Do you care to say why?

joe

Well, if not all bolts had reached the target torque specification, then you obviously have to keep going until you do. Multiple passes would help ensuring the part is being clamped uniformly, but the service data usually takes care of that.

I have personally done more than one pass (after reaching the final torque specs) only to ensure I haven't MISSED any bolts. A third pass is yet another confirmation.

On TTY fasteners, I mark the bolt to keep track of which one's are done.

BTW, if anyone is interested in differences between torque-to-spec, torque-to-angle and torque-to-yield, we had a good conversation on the LS1TECH website:

Seems like a lot of folks confuse them, or just don't understand what is what.

Since torque values are specified for a reason, if I am torgueing any bolt or nut, I am going to be sure sure sure. A second or 3rd pass is warranted, in my mind.

A beam style torque wrench is not exact enough. As I said above, if I am going to torque it to spec I am gonna be 100% sure. A beam style can be right on the money or close enough. Why torque at all if gonna be close enough. It is old tech. I believe in the digital/alarm type and then a click type, that may or may not be calibrated correctly.

OR VietVet said:

I believe in more than one pass. If is 65 ft lbs, then I do a pass at 50-55 ft lbs and then a second pass at the same to know that I am at the same point with all of them. Then I would do two passes at 65 ft lbs. I also use a digital torque wrench and if not handy I would use a click type. Beam style wrenches are not the way to go at all.

Also, I prep all threaded holes, in the block or in a nut, with a chase and I do not lube threads.

Click to expand...

This is essentially how I do it, unless the torquing steps are specified by the part or procedure. For example, when I torque my wheel lug nuts (deez nutz ) I'll run them to 100 ft lbs, then 120, then 140 and go over them again at the final. Might be overkill but keeps things even and certain.

homesick said:

... didn't say so specifically (my error), but we're assuming that not all bolts have reached 65FtLb after the first pass.

Click to expand...

Final pass is incomplete until every bolt has reached 65FtLb. Mark each bolts as it achieves spec.

When I used to tighten heads or intake manifolds, I'd wait 15min before the 2nd pass.