Do you usually re torque head bolts?
Do you usually re torque head bolts? My 1/2" Crapsman torque wrench broke last night so I used my backup 3/8". I only got 1 head on but I want to get my hands on a Snapon torque wrench.
What I did with the one head was, after going 15/25/45/75, I backed all the bolts up a bit and re torqed them. The angle did increase after I did this.
My question is, when I get my hands on a REAL torque wrench, should I just check the bolts by tightening them, or backoff and re tighten again? Note that I only have one head on so far and I used the ARP Ultra thread sealer.
Will this fatigue the ARP bolts?
What I did with the one head was, after going 15/25/45/75, I backed all the bolts up a bit and re torqed them. The angle did increase after I did this.
My question is, when I get my hands on a REAL torque wrench, should I just check the bolts by tightening them, or backoff and re tighten again? Note that I only have one head on so far and I used the ARP Ultra thread sealer.
Will this fatigue the ARP bolts?
I've always used a 3/8" Craftsman torque wrench, I've done head gaskets on 3 LT1s, they never had any problems. Are there studies out there that show Craftsman torque wrenches are way off or something?
Why did you back off the bolts and retorque them? Backing them off negates the purpose of torquing them in stages. Just make two passes per torque spec - that's all you need.
The bolts won't fatigue. They can be used over and over again.
The bolts won't fatigue. They can be used over and over again.
Never have.
I dunno. I've had the same Craftsman 1/2" and 3/8" drive torque wrenches for the last 11 years and they work perfectly, and as stated, ARP bolts will not fatigue. I'm using the same ones that I bought like 6 years and a-half-dozen-times-the-heads-have-been-off-the-block- ago.
I dunno. I've had the same Craftsman 1/2" and 3/8" drive torque wrenches for the last 11 years and they work perfectly, and as stated, ARP bolts will not fatigue. I'm using the same ones that I bought like 6 years and a-half-dozen-times-the-heads-have-been-off-the-block- ago.
I'll have to find the article for the rationale behind the whole thing.
I dunno. I've had the same Craftsman 1/2" and 3/8" drive torque wrenches for the last 11 years and they work perfectly, and as stated, ARP bolts will not fatigue. I'm using the same ones that I bought like 6 years and a-half-dozen-times-the-heads-have-been-off-the-block- ago.
Trending Topics
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
Gas Monkey Built a 6-Wheel Ferrari Testarossa With a Corvette LT4 Engine
Verdad Gallardo
7 Most Reliable High-Performance Engines GM Has Ever Built
Verdad Gallardo
Amazing '71 Camaro Restomod Is Modern Muscle Car Under the Skin
Verdad Gallardo
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Here are a few things related to head bolt torque.
1. Retorquing is typically done to compensate for the head gasket taking a set, usually after running & heat cycling.
2. Typically it is best to retorque bolts when they are new. This actually smooths out the threads whch can result in a slight additional movement as you noted, due to less thread friction. Many bolt manufacturers recommend retorquing on new critical fasteners. I always do on my engine builds.
3. When you retorque, only loosen 1 bolt at a time & retorque it in 3 steps as recommended. Do not loosen all & retighten.
As for you retorquing the heads, it would not be a bad idea if this is a high HP application (forced induction or nitrous) Typically I never see any head gasket failures on normally aspirated vehicles, other than high mileage stock motors.
As an FYI, I only typically see the long head bolts change position during a retorque. The short ones do not seem to change as much.
1. Retorquing is typically done to compensate for the head gasket taking a set, usually after running & heat cycling.
2. Typically it is best to retorque bolts when they are new. This actually smooths out the threads whch can result in a slight additional movement as you noted, due to less thread friction. Many bolt manufacturers recommend retorquing on new critical fasteners. I always do on my engine builds.
3. When you retorque, only loosen 1 bolt at a time & retorque it in 3 steps as recommended. Do not loosen all & retighten.
As for you retorquing the heads, it would not be a bad idea if this is a high HP application (forced induction or nitrous) Typically I never see any head gasket failures on normally aspirated vehicles, other than high mileage stock motors.
As an FYI, I only typically see the long head bolts change position during a retorque. The short ones do not seem to change as much.
Stock LT1 Head Bolts are T2Y Now, a set of ARP Stainless Steel head bolts, those can be reused and re-torqued, no problem.
TECH Regular
Joined: Apr 2007
Posts: 420
Likes: 0
From: Kempner, TX
I wonder how this ever got started anyway. Someone posted it or said it and others just picked up on it and ran with it?
Jake
There is no such thing as a torque to yield bolt.... this is only the method for tightening any bolt. Once it reaches a certain stretch value it yields.
As for the LT1, the 92-95 states a specific torque value.
Some of the specs for the 96-97 manuals state 22ftlb plus 80deg on long & 67deg on short. This is torque to yield.....
If you have a 96 up car I would never reuse the bolts. Personally I also question reuse on the earlier cars, as I do not know the method for installation at the factory.....
This is where the myth or FACT came from.
As for the LT1, the 92-95 states a specific torque value.
Some of the specs for the 96-97 manuals state 22ftlb plus 80deg on long & 67deg on short. This is torque to yield.....
If you have a 96 up car I would never reuse the bolts. Personally I also question reuse on the earlier cars, as I do not know the method for installation at the factory.....
This is where the myth or FACT came from.
Just to make sure I understand correctly, ARP head bolts can be reused. I have ARP head bolts from my original head swap and are in great shape and would like to use them on my current 355 build.
TECH Veteran
Joined: Dec 2008
Posts: 4,147
Likes: 62
From: Little Rock, AR
There is no such thing as a torque to yield bolt.... this is only the method for tightening any bolt. Once it reaches a certain stretch value it yields.
As for the LT1, the 92-95 states a specific torque value.
Some of the specs for the 96-97 manuals state 22ftlb plus 80deg on long & 67deg on short. This is torque to yield.....
If you have a 96 up car I would never reuse the bolts. Personally I also question reuse on the earlier cars, as I do not know the method for installation at the factory.....
This is where the myth or FACT came from.
As for the LT1, the 92-95 states a specific torque value.
Some of the specs for the 96-97 manuals state 22ftlb plus 80deg on long & 67deg on short. This is torque to yield.....
If you have a 96 up car I would never reuse the bolts. Personally I also question reuse on the earlier cars, as I do not know the method for installation at the factory.....
This is where the myth or FACT came from.
The torque/angle method is a more precise way of tightening a fastener that helps negate friction errors. A TTY bolt must always use the torque/angle method, but a normal bolt can use either (if both methods are supplied). The torque/angle method has been used in industrial applications for many years.
TECH Veteran
Joined: Dec 2008
Posts: 4,147
Likes: 62
From: Little Rock, AR
TECH Regular
Joined: Apr 2007
Posts: 420
Likes: 0
From: Kempner, TX
TTY bolts have been used for years on European cars, but more recently on American made cars. Those are the ones that should not be re-used. Like so many other thngs, though, where guys deviate from what's recommended, there are some who claim TTY bolts, too, can be reused, but I definitely wouldn't.
Jake