I have been told that my brother and I (who have done ALL of our own engine work except changing valve springs cos we're lazy) are LS1 morons because you supposedly CAN re-use the STOCK head bolts for a head swap. Now, in the GM Service Manual it states you must replace them b/c they are torque-to-yield bolts and once they are stretched to their specified torque they cannot be re-used. Is this not correct?

 

You really really really really should change them they arent that expensive and the cons of not changing them are not worth the risk..

 

Oh I know I'm right. I just need more support, got some from Federal-Mogul's sight, too.

 

Get head studs and never have any worries!!!! <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

 

you are correct. You absolutely cannot reuse torque to yield headbolts.

You're probably getting ripped on by those old shadetree type mechanics that still think cars are just like they were in the 60s. <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" /> <img border="0" title="" alt="[Roll Eyes]" src="images/icons/rolleyes.gif" />

 

Agave, you nailed the "getting ripped" part <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Ignorance is bliss.

 

I've always been told that you should not reuse the bolts... however, my dad's an auto mechanic (jaguars) and originally Jaguar told them not to reuse head bolts... then they found they could save money by reusing them so Jaguar said they could be reused once and when you reuse them you have to put a cut in the top to indicate it's already been used once.

Then jaguar came back and said they could reuse them up to 2 times...

If our cars are similar, i'm guessing the right way to do it is replace the bolts, but it would be possible to reuse the bolts a couple times... dunno though, i know the jaguar motors use torque to yield bolts but maybe they're a different type?

 

TTY bolts, once stretched, have reached their physical limit. They WILL NOT retain the same torque capacity if they are re-used and they are weaker if reinstalled. Motors are motors, if they're Jaguars to Geo Storms. Jaguar was cutting corners, period.

Take a gander at this excerpt from a page and it's graph:
"Torque-to-yield (TTY) head bolts are designed to stretch when used. Once stretched, they are not as strong as before. Consequently, they cannot provide the same amount of clamping force and may break or shear off if reused.

The TTY bolt-tightening procedure is designed to provide a better, more uniform seal. On the factory assembly line, sophisticated torquing equipment is used to tighten head bolts beyond their yield point. This stretches the bolt slightly and evens out the loading so each bolt provides almost exactly the same amount of clamping force on the head gasket.

Because the tightening procedure permanently stretches the bolts, there is a risk of breakage if reused. Since there is no way to tell how many times such a bolt has been reused, most aftermarket gasket manufacturers say the risks of reusing TTY head bolts far outweigh replacement cost. For that reason, new TTY head bolts are often included in head gasket sets.

Applications where new TTY head bolts are recommended include Chrysler's 2.2L and 2.5L engines, Ford's 1.6L and 1.9L Escort engines, General Motor's 1.8L, 2.0L and 2.5L fours, 3.0L V-6 and 381 diesel V-8.

When new TTY head bolts are installed, a special tightening procedure must be used to achieve proper results. After bolts have been tightened to the recommended torque, each bolt must be given an additional twist. The amount of twist may be 1/4 turn or more, or specified as so many degrees of rotation. Using a simple "torque-to-angle indicator" tool when making the final twist ensures uniform loading and prevents overtightening." (http://www.milexautocare.com/eng_info/eng_info11.htm )

<img src="http://www.milexautocare.com/eng_info/torquetoyield_heads.gif" alt=" - " />

<small>[ October 08, 2002, 06:45 PM: Message edited by: NastyC5 ]</small>

 

Directly from the GM service document ID #322890 for a 2000 Camaro 5.7L LS1:

Important
Do not reuse the M11 cylinder head bolts. Install NEW M11 cylinder head bolts during assembly.

Do not use any type sealant on the cylinder head gasket (unless specified).

The cylinder head gaskets must be installed in the proper direction and position.

Also:
<img src="http://www.z71.net/head.gif" alt=" - " />
Tighten the cylinder head bolts-

Tighten the M11 cylinder head bolts (1-10) a first pass in sequence to 30 N·m (22 lb ft).

Tighten the M11 cylinder head bolts (1-10) a second pass in sequence to 90 degrees using the J 36660-A .

Tighten the M11 cylinder head bolts (1,2,3,4,5,6,7,8) to 90 degrees and the M11 cylinder head bolts (9 and 10) to 50 degrees a final pass.

Tighten the M8 cylinder head bolts (11,12,13,14,15) to 30 N·m (22 lb ft). Begin with the center bolt (11) and alternating side-to-side, work outward tightening all of the bolts.

 

And if you are concerned with the high cost of head bolts, you are now in luck. SDPC is a sponsor here and offers GM head bolts as a set at a much reduced price from buying them separately
Check it out:

Head bolt set, P/N 12498545, $16.95 ea, need 2, thats $33.90 total price + small shipping cost

If you bought these bolts separately, they would cost appox $64 (discounted price from another GM parts dealer) + shipping