OK to Re-Use Later Model Headbolts ? - Team Camaro Tech
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post #1 of 18 (permalink) Old Apr 28th, 04, 01:47 AM Thread Starter
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I was talking with a friend yesterday who was having to replace the head gaskets on his daughter's '95 Camaro with the 3.4L V6. When he bought the gaskets from the dealer, they told him he would need to get a new set of head bolts too, because they're not to be re-used.

Has anybody else ever heard this ? It makes me wonder if the same is true for my '96 vortec 350 head bolts. I did notice that the shoulder of the bolt narrows a bit at about 1/2" below the head of the bolt if that matters. I guess these torque to 70 ft lbs like the older bolts ? I've got a set of the older style head bolts if they would be better to use. Thanks for any comments or advice, Ron.
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post #2 of 18 (permalink) Old Apr 28th, 04, 02:17 AM
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Use new bolts and use an angle torque meter(?) to tighten. Newer bolts used are torque-to-yield, meaning they are stretched (fractured) to a predetermined length, hence, using an angle meter.

Fastener engineers have done plenty of testing and so far, have determined this method the best.
Use a torque wrench for initial setting, then sub in an angle meter and continue for a number of degrees. The bolt is stretched. Use 1 time.

Be sure to get the correct thread lubricant and torque setting, both wrench and angle.

Maybe others here will educate us......

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post #3 of 18 (permalink) Old Apr 28th, 04, 02:52 AM
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Ron,
I do not beleive the 96 Vortec bolts are torque to yeild bolts which require replacement. They DO use the "Torque plus Angle" method of tightening. A common misconception is that any bolt that is tightened using the "Torque + Angle" method of tightening is always a torque to yield bolt. This is not always true. Unfortunately, there is no rule of thumb to use ... you MUST go by the factory manual to see if the bolts need replacement. If you are using the Vortec heads on an older engine, then there is no problem using the old style bolts and torque specifications. If you are going to use the new bolts, use the new torque specs. I will try to find out for certain on the replacement of the bolts, but I am almost positive it is not required on this engine. If it is, I will let you know later today.

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post #4 of 18 (permalink) Old Apr 28th, 04, 04:06 AM Thread Starter
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Thanks for the replies; I'm constantly amazed by how little I know !

Is it the '96 model block, or the newer bolts that require the "torque plus angle" method of tightening ? I have a pretty decent 1/2" drive Craftsman torque wrench, but I don't have a angle torque meter. I don't want to buy one since I hopefully won't be replacing head gaskets often.

If the new style bolts are the reason for this new tightening requirement, can't I just use the old style ones, or are the threads in the newer blocks different than the old ones ? Thanks, Ron.

[ 04-28-2004, 06:53 AM: Message edited by: Rons68 ]
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post #5 of 18 (permalink) Old Apr 28th, 04, 04:13 AM
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Thanks Bill, awaiting your reply to educate us.
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post #6 of 18 (permalink) Old Apr 28th, 04, 06:00 AM
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Unless you get an absolute go ahead to reuse the old bolts, get new ones. Why take the chance?
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post #7 of 18 (permalink) Old Apr 28th, 04, 06:06 AM
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Quote:
Originally posted by Rons68:
Thanks for the replies; I'm constantly amazed by how little I know !

Amen to that, brother!

(meaning I'm in the same boat as you, NOT that I'm amazed at how little you know!!)


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post #8 of 18 (permalink) Old Apr 28th, 04, 06:48 AM Thread Starter
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If I can't re-use the bolts that came with my '96 vortec engine or the older ones that I have (they came from another older model 350 - a '75 model I think), wouldn't I be better off to buy some ARP bolts instead of a piece of crap that you can use one time & then throw away ?
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post #9 of 18 (permalink) Old Apr 28th, 04, 09:06 AM Thread Starter
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http://www.sallee-chevrolet.com/Disc...html?975436095

If Bill verifies that the above is true, what should I torque the bolts to ? I don't know where I could find an angle torque meter that I could borrow, so is it possible to torque to a certain spec and be OK ?
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post #10 of 18 (permalink) Old Apr 28th, 04, 09:37 AM
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ARP probably makes re-usable head bolts for pretty much any engine out there- you just gotta use their specs to tighten them down.
i know if i ever get around to building an LS1 for the Nvoa, it is getting all ARP hardware so i will never have to worry about whether or not the bolts need to be replaced if i swap heads or check the main bearings or something.
check the avaialbility of ARP headbolts for the 3.4 in question- i bet that if they make them, they are comparable in price to the stockers that GM wants to sell you to make a few bucks- which is the whole point of torque to yield fasteners, anyways- revenue generation for the dealers and parts suppliers.

you don't plan sincerity.
you have to make it up on the spot.

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post #11 of 18 (permalink) Old Apr 28th, 04, 10:05 AM Thread Starter
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Thanks for the reply, novaderrik. My neighbor has the 3.4L; he has already bought the GM bolts. I've got the 5.7L vortec, and if I have to buy bolts, they will be ARP. Thanks !
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post #12 of 18 (permalink) Old Apr 28th, 04, 02:26 PM
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Guys,
I apologize ... things were so crazy today at the shop I plain forgot to check ... suffering from CRS syndrom for sure Will try again on Thursday.

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post #13 of 18 (permalink) Old Apr 28th, 04, 02:49 PM
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Allright ... got smart and looked in my AERA software and here is what I found. It verifies that even though the bolts use the "Torque -Angle" method to tighten them, they are NOT TTY bolts and can be reused.

Cylinder Head Installation On
1996-98 GM 5.7L VIN R Engines

The AERA Technical Committee offers the following information on cylinder head installation for 1996-98 GM 5.7L VIN R engines. This information is somewhat different than previous engines. GM is now recommending a torque turn method of tightening the cylinder head for this engine. It does not however, use a torque-to-yield bolt to mount the cylinder heads.

The cylinder head mounting bolts may be reused if they are not damaged in the threads or show neck-down or stretch condition. The bolts should be thoroughly cleaned of sealer before inspection and installation. Cleaned bolts should have a coating of GM sealing compound Part #1052080 applied to the threaded area only. The use of an aftermarket equivalent sealing compound is also acceptable to use on threads.

Follow the steps listed below to correctly install head gaskets for this engine being careful not to get any seal on the head gasket mating surfaces or gasket.

1. Place the head gasket over dowels with the bead up.
2. Carefully guide the cylinder head into position over the dowel pins and gasket.
3. Coat threads of the head bolts with sealing compound and finger tighten all bolts.
4. Tighten all bolts in sequence shown below to 22 ft. lbs.
5. Tighten all bolts in sequence an additional turn in degrees, using J 36660 tool.

Short bolts (3,4,7,8,11,12,15,16)
additional 55 degrees.

Medium Bolts (14,17) Additional 65degrees

Long Bolts (1,2,3,5,6,9,10,13) Additional 75 degrees


The bolt numbers correspond to the "normal" Small Block torque sequence.

The AERA Technical Committee

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post #14 of 18 (permalink) Old Apr 28th, 04, 07:28 PM
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Sounds like a huge PITA to me. Why would they use this method of torqueing bolts? The old way worked on a billion engines out there...why change it?

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post #15 of 18 (permalink) Old Apr 28th, 04, 07:59 PM
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Maybe less warranty repairs?

Everett-
Not to nick-pick, but the fastener is strained , not fractured. If it fractures, it fails.

I would think that any bolt can be reused as long as it does not go past its yield point. The TTY method brings the steel up to the yield point, which means it will not go back to its original length when unloaded. If you don't stretch the fastener to or past its YP, it will return to its original length. So from an engineering stantpoint, you're good to go.

This is all provided that you follow the above instructions EXACTLY...

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Art Morrison Ent. Inc.
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