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).

 

[62barsoom]

Well crap, I'm confused again. Ready to put the heads on tomorrow. Got the bolts cleaned up and the block chased. But now I'm going with y'alls knowledge and experience. So new bolts, torque to the first step, and then the degree value as in the MERCRUISER PUB?

 

[454C2500Longbed]

Well crap, I'm confused again. Ready to put the heads on tomorrow. Got the bolts cleaned up and the block chased. But now I'm going with y'alls knowledge and experience. So new bolts, torque to the first step, and then the degree value as in the MERCRUISER PUB?

If it were me I'd get regular bolts and torque them to a ft-lb spec. I'm no GM engineer obviously, but it's worked quite well for decades. Then you can reuse them, should you ever have to take the heads off.

 

[L31MaxExpress]

Well crap, I'm confused again. Ready to put the heads on tomorrow. Got the bolts cleaned up and the block chased. But now I'm going with y'alls knowledge and experience. So new bolts, torque to the first step, and then the degree value as in the MERCRUISER PUB?

Same as the GM service manual. There are 3 different degree angles for the 3 lengths of bolts too. Pay attention there. The short bolts get turned the least. The middle length bolts next to the oil drain back holes on the ends in the center row get an intermediate value. The longer bolts get the highest value. Do not have the specs sitting in front of me at the moment. Chances are you will have some that feel spongy even doing the service manual method. Resist the temptation to turn it more unless you want to hear a snap and righty tighty to become righty loosely.

If you go ARP, 65 ft/lbs MAX on bolts or studs in a factory block after sanding the bottom of the washers facing the head with 80 grit sand paper. Lube on the shank and under the bolt head only, none on the head face side of the washer. Sound advice from the late Joe Sherman of Sherman Race engines.

Learned my head bolt lesson the hard way a couple of years ago. Involved an in-chassis head removal on both banks in my 97 Express on an engine that had 1,000 miles on it at the time. Avoid JEGS brand "Made in the USA" head bolts too even if they look tempting compared to ARP in price. They lost a customer in the whole ordeal that had spent $1000s with them over the prior 2 decades. 4 broken/cracked bolts and 5 cracked in half washers. 2 ruined head gaskets, 2 intake gaskets, 2 header gaskets and probably 10 hours of labor to do it again while I had Covid. It was fun.

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[Sean Buick 76]

Yes I personally only use ARP bolts or studs torqued with a good torque wrench. and I agree with Joe Sherman’s advice on the ARP lube protocol.