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

[L31MaxExpress]

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.

That would be the place.

 

[kylenautique]

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.

Sorry if I got the terminology incorrect. Vortec engines state to use angle torque, and older SBC 350s only use a ft lbs torque value. I'm not a fan of reusing head bolts, but I can purchase the older style or the OEM vortec bolts that require angle torque. My last vortec engine I built I used the OEM angle torque bolts and torqued them properly with an angle torque wrench per the manufacturer specs.

I'm just really curious what others are doing.

 

[Hipster]

Sorry if I got the terminology incorrect. Vortec engines state to use angle torque, and older SBC 350s only use a ft lbs torque value. I'm not a fan of reusing head bolts, but I can purchase the older style or the OEM vortec bolts that require angle torque. My last vortec engine I built I used the OEM angle torque bolts and torqued them properly with an angle torque wrench per the manufacturer specs.

I'm just really curious what others are doing.

Vortecs are a light duty head already prone to cracking. I buy new bolts and do them like the book says. I'm not sure why people think they no more than the engineers that designed the stuff and that includes Mercruiser(a re-seller) publishing a cross reference table

 

[454cid]

Vortecs are a light duty head already prone to cracking. I buy new bolts and do them like the book says. I'm not sure why people think they no more than the engineers that designed the stuff and that includes Mercruiser(a re-seller) publishing a cross reference table

I don't think I'd call Mercruiser a re-seller. They build engine based on GM designs, they're not just buying engines to re-sell.

 

[L31MaxExpress]

I don't think I'd call Mercruiser a re-seller. They build engine based on GM designs, they're not just buying engines to re-sell.

I beg to differ. The small block and big blocks are marinized from already assembled GM longblocks for the most part. Their 300 hp 350 was the Ramjet longblock using stamped steel rockers and the 383 was the HT383.GM even supplied those long blocks with the marine intake already on them.

 

[0xDEADBEEF]

Personally, I just get ARP bolts and follow the directions. Harder to mess up, IMO.

I did see an interesting video where a guy measured the clamping force with torque to yield and he showed that once it yields the force stays constant for a long while until it falls off a cliff or breaks. Meaning if it yields at 45 degrees, it doesn't matter if you continue cranking in the other X degrees called for in the spec or not. The force is the same. You can see why they just call for some large value where a bolt should yield but not break (should being the key word).