Vortec head bolts.. Torque to yield or old school torque method?

[kylenautique]

Hey everyone. I'm getting ready to assemble my new Vortec 5.7. Just got my heads back from the machine shop. What are y'all doing with head bolts? I'm going to install new bolts. I know that the OEM bolts are torque to yield bolts. Is there any reason/benefit to installing TTY bolts? Is it ok to install the older non TTY SBC 350 head bolts, and do the 25, 45, 65ft lbs torque pattern?

 

[Supercharged111]

You're probably going to get multiple answers here. I went with the old school torque values on my 1500 back in 2016 and the sky didn't fall.

 

[kylenautique]

You're probably going to get multiple answers here. I went with the old school torque values on my 1500 back in 2016 and the sky didn't fall.

I'm leaning towards the old style bolts/pattern, but I'm real curious on what others are doing.

 

[Drunkcanuk]

No dog in this fight, never done it
But if GM's engineers, lawyers and warranty guys signed off on TTY, I'd stick with that.

 

[Schurkey]

According to the '97 C-K GM service manual, the newer head bolts are torque-angle, NOT torque-to-yield. There's nothing in there about having to replace them.

But another guy on this forum has a lovely photo of three newer head bolts with one of them stretched from use.

I've re-used torque-angle head bolts on my Lumina. I've also eliminated any guesswork by buying ARP old-style reusable bolts for the aluminum-headed, Vortec short-block 5.7L in my K1500.

 

[GoToGuy]

Your wisest choice is to torque to what your specific hardware is manufactured for. Over the counter GM bolts follow the service manual guidance. Whether old style basic torque or new style Vortec, LS and on.
The bolts are produced based on specs provided by the engineers. Engines, computers and hardware gets smarter.
Use what your comfortable with as long as it confirms to accepted hardware standards, bolts, studs, washers , nuts, TTY, Torque to Angle, and performs to task.
The only absolute is the engine designers.

 

[Erik the Awful]

Torque angle is supposed to be superior to basic torque. As we've seen reports, a well lubricated bolt will give a lighter torque spec and you can strip threads. With torque angle, you snug the bolt so that you know all the slack is gone. Then you turn the bolt an additional number of degrees, removing friction from consideration. I think the place where torque angle fails is when parts are warped and they snug up before you get the warp flattened out.

Torque to yield is a cheapskate solution to a problem mechanics never had.

 

[Hipster]

I used a ft lb conversion table from a Mercruiser manual and stretched 2 bolts on one head before I stopped. Fel Pro bolts. I do them by angle now.

Old school non-TTY head bolts didn't have a necked down shank. Very easy to go too far with a clicker type torque wrench on tty fasteners. A smidge past good is ruined.

 

[L31MaxExpress]

I used a ft lb conversion table from a Mercruiser manual and stretched 2 bolts on one head before I stopped. Fel Pro bolts. I do them by angle now.

Old school non-TTY head bolts didn't have a necked down shank.

The newer GM and Felpro bolts are TTY. VortecIroc, a former GM powertrain engineer even stated that fact on TGO. He was a powertrain engineer when the Vortecs were being built. I have felt that style bolt yeilding using the TTA method.

 

[Hipster]

The newer GM and Felpro bolts are TTY. VortecIroc, a former GM powertrain engineer even stated that fact on TGO. He was a powertrain engineer when the Vortecs were being built. I have felt that style bolt yeilding using the TTA method.

When I see A necked down shank I'm already assuming TTY whether they are or aren't and goto Alldata or CCC to get particulars. New vehicles are loaded with tty fasteners throughout . Suspension etc.

TGO= Third Gen? been years but there used to be some very knowledgeable people there.