Question about torquing the heads.

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Astro

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Hey all,
I have a question about my 96 sierra 5.7l vortec head job. I bought a brand new quinn torque wrench with a built in angle system to do the job. After you reach the angle you want, it tells you what torque you reached. I cleaned the threads before installation to ensure smooth insertion.

I torqued both heads (22lb/ft first pass, long 75d, med 65d, short 55d second pass), but what's been bothering me is the variation in all the torque values I got after completing the angle adjustment. I know the ultimate goal is to reach a certain stretch right? Also there's the fact that it's impossible for me to be absolutely consistent with a wrench that beeps at me versus one that clicks haha. That introduces slightly more variation.

I've read in other places to verify torque after finishing up, but how the hell do you even do that? Any help would be appreciated.
 

SAATR

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With torque-to-angle fasteners, there is a rarely a fixed torque spec given that will approximate what you're doing with a preload+angle torque procedure. That's intentional, to prevent you from simply torquing to the given number rather than using the angle procedure. The whole point of TTA is to eliminate the variables of fastener length, thread cleanliness, friction of the threads/shank/head of the bolt, etc. Since SBC's have such a long history that largely predates TTA's usage, you can go back to the "old" way of torquing the head bolts, usually with good results.

A few of questions: When you say your cleaned the threads, I assume you mean the threads in the block, correct? Did you use new head bolts with preapplied sealant, or reuse your old bolts with fresh thread sealant applied? When you did the initial torque to 22ftlbs, did you do the pattern several times or only once? Only running the preload pattern once will often leave some bolts much looser than others, so the angle turn is not applying nearly as much clamping load as it should.
 

Astro

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With torque-to-angle fasteners, there is a rarely a fixed torque spec given that will approximate what you're doing with a preload+angle torque procedure. That's intentional, to prevent you from simply torquing to the given number rather than using the angle procedure. The whole point of TTA is to eliminate the variables of fastener length, thread cleanliness, friction of the threads/shank/head of the bolt, etc. Since SBC's have such a long history that largely predates TTA's usage, you can go back to the "old" way of torquing the head bolts, usually with good results.

A few of questions: When you say your cleaned the threads, I assume you mean the threads in the block, correct? Did you use new head bolts with preapplied sealant, or reuse your old bolts with fresh thread sealant applied? When you did the initial torque to 22ftlbs, did you do the pattern several times or only once? Only running the preload pattern once will often leave some bolts much looser than others, so the angle turn is not applying nearly as much clamping load as it should.
Thanks for the reply SAATR! I cleaned the block threads and used new bolts with preapplied sealant. I did only do the initial torque one time, unfortunately. That's good to know about the bolt stretch vs torque value, thanks.

In this case, I would say the only thing I have to stand on is the fact that my torque wrench will only start counting degrees when it reaches within 5% of the initial torque setting of 22lb/ft. When I TTA, it started recording angle pretty much immediately on all the bolts.

Idk what do you think?
 

L31MaxExpress

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I once had good luck torquing to 65 ft/lbs. While Felpro denies the new bolts they make are TTY, something has definitely changed. I stretched 3 bolts with a torque wrench I had just tested the calibration on trying to get to 65 ft/lbs. I bought another set of bolts and used the TTY method on this last 350 I am building. Even then several of the short bolts were yeilding, felt like plastic or rubber and felt like they would fail before 55*. As soon as I felt them starting to yeild, I stopped turning on them. Probably around 50*. All these head bolt issues make me wish I had a 30+ year old set of decent used 5/8" hex OEM old bolts laying around.
 
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Astro

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I once had good luck torquing to 65 ft/lbs. While Felpro denies the new bolts they make are TTY, something has definitely changed. I stretched 3 bolts with a torque wrench I had just tested the calibration on trying to get to 65 ft/lbs. I bought another set of bolts and used the TTY method on this last 350 I am building. Even then several of the short bolts were yeilding, felt like plastic or rubber and felt like they would fail before 55*. As soon as I felt them starting to yeild, I stopped turning on them. Probably around 50*. All these head bolt issues make me wish I had a 30+ year old set of decent used 5/8" hex OEM old bolts laying around.
Wow that's a little scary. I'm not what sure it feels like when the bolt is yielding. It just felt like they were getting tighter. I guess we'll see man. I miss the old style as well. It's hard for us old farts isn't it?
 

Hipster

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I once had good luck torquing to 65 ft/lbs. While Felpro denies the new bolts they make are TTY, something has definitely changed. I stretched 3 bolts with a torque wrench I had just tested the calibration on trying to get to 65 ft/lbs. I bought another set of bolts and used the TTY method on this last 350 I am building.
Had the same issue trying to torque to a number with felpro bolts years ago. Overstretched 2 bolts on the first head.

This was after looking in a service manual and then scouring the internet for a better way. The better way, wasn't.
 

L31MaxExpress

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Wow that's a little scary. I'm not what sure it feels like when the bolt is yielding. It just felt like they were getting tighter. I guess we'll see man. I miss the old style as well. It's hard for us old farts isn't it?
It feels like you are twisting rubber. Goes from the constant torque increase feel to a a liquid feel where you are turning but its not tightening. When right tighty becomes right loosey is close at that point.
 

Astro

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Had the same issue trying to torque to a number with felpro bolts years ago. Overstretched 2 bolts on the first head.

This was after looking in a service manual and then scouring the internet for a better way. The better way, wasn't.
How did you discover you overstretched them?
 
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