NovaKeagan

I understand that the head bolts, connecting rod bolts, and harmonic bolt, are all torque to yield.

I noticed the outer main cap bolts are also marked with and angle for the final pass? Nobody on the internet seems to state that they're torque to yield though, I'm confused?

reference: https://www.bakesonline.com/media/resourcelibrary/Indmar_6.0LQ9RepairSpecs.pdf

TrendSetter

torque angle doesnt mean torque to yield (TTY)
the side main bolts are not TTY
the rod bolts are not TTY

strutaeng

Yup, only the head bolts and harmonic balancer bolt are TTY.

Seems like a lot of folks see degrees on the specs and automatically assume TTY. Not true.

LS1Formulation

iTrader: (13)

This will unfortunately add to your confusion, but if you are reusing main cap bolts, you shouldn't use the torque to angle method to tighten them. I tried, and my torque value was lower than what it should have been. Had a few bolts end up in the mid 40's. Not ideal. I ended up torqueing to a set lb.ft. value, inner 13mm @ 65 lb.ft. and outer 15mm @ 55 lb.ft. This video gives a good explanation:

Che70velle

iTrader: (6)

This is exactly how I do it also. Good info here.

KCS

iTrader: (20)

You and I usually see eye-to-eye when it comes to engine stuff, but not this time. I would stick with the TTA value over the torque value everytime. The whole principle behind using an angle is to mitigate the frictional inconsistencies from using rotational torque. Somebody correct me if I’m wrong, but I think the problem is that a lot of people, including the guy in the video, correlate the rotational torque on the bolt with the clamping force the bolt provides. This is just bad logic.

FWIW, the guy in the video mentions how weird it is that there are three different TTA values for the LS rod bolts. That’s because there are two different bolt designs for the LS PM rods (not including the Ti rods) and each had a different TTA value. GM then updated the TTA value for one of the designs, leaving three different values floating around the internet.

Che70velle

iTrader: (6)

Call me old school I suppose. I simply don’t bother with TTA. My digital Snap-On torque wrench hasn’t failed me yet, and Lord knows I wore out some click style torque wrenches through the years. I honestly don’t build many stock fastener engines, but when I do, I have reverse engineered the required TTA requirements (with my digital wrench) and just go to the torque value. Am I turning the fasteners any more or any less? No. It’s just a different way of getting there in my opinion.

strutaeng

I tried watching that video and the guy kept rambling on and on and on...tuned out halfway through last night. LoL.

I tried again and realized he at one point called the torque wrench a "torque converter" LoL. Come on dude... He "thinks" he's an expert in his mind (who isn't, right?)

I would think that TTA is more accurate way because each bolt will stretch (and therefore will have the same stress and preload or tension by Hook's Law) irrespective of the friction of the threads. The friction of the threads could be be metal-to-metal (good), but if there's maybe gunk, not good or something else going on. Maybe too much friction on the head of the bolt against the cap? Too much friction of the threads due to machining tolerances too tight? I'm sure there's other variables that can play a role. TTA eliminates those variables.

That's why it doesn't matter if the torque is different in each bolt head. If the bolt is stretched the same amount (turned a certain amount of degrees in this case) then that's what matters most. Think about like this: with TTA you are tensioning each bolt (fastener shaft) the same amount. With torque spec, there's other variables that affect torque on the fastener HEAD, and the fastener shaft may or may not get tensioned the same amount.

Best example of torque specs NOT achieving consistent faster stretch are certain connecting rod bolts, which have to be double checked with the special tool to confirm stretch.

A review a basic engineering mechanics of materials concept may help folks understand this better.

Che70velle

iTrader: (6)

No, I agree 100% with the TTA and it’s procedures as well as it’s purpose. It’s a quality way of achieving proper fastener torque (stretch).
I’ll put it this way…and it’s my opinion only which is meaningless…we are not building spacecraft here. There’s not a single use of TTA fasteners in professional Motorsports engine building that I’m aware of. I fully know with certainty that my friends still in the Cup engine industry aren’t using anything that ARP offers in a TTA form….they are still doing it the old fashioned way with torque wrenches.
Is TTA a quality method of achieving proper fastener stretch? Yes. I say that you do whatever makes you comfortable. All of the builds I’ve done out of my shop with OEM fasteners are still running fine and I didn’t use the TTA method. If I had of used the TTA method, would they run any different or last any longer? The answer is no.

grinder11

iTrader: (1)

TTA and using a torque wrench BOTH depend on having the threads as friction free as possible. TTA is a good way to do it. But so is an accurate torque wrench. Using an old style late 1960s beam pointer Craftsman torque wrench, as well as a more modern clicker Craftsmen torque wrench, in all the years of building 10,000+ rpm air cooled motorcycle engines, to automotive V8s, I have never lost a head gasket, had a main cap loosen, spun a bearing or seen a rod come thru the block. Quality thread lube is key in either case. Nowadays I use ARP lube, but back in the day, STP, sometimes mixed with Dutch Boy white lead (!!) was all we had. It worked pretty damn good, too! But if your threads start galling, neither TTA or a torque wrench will be accurate if the threads partially seize.....

LS1Formulation

iTrader: (13)

When I assembled my engine intially, the bolts were on their third ( or fourth ) torqueing. Once at the factory, once or twice at the machine shop, and then as I assembled. I did the torque to angle and wasn't happy with the ending torque values. I ordered a brand new set of main bolts and did those torque to angle, and they were all 10-12 lb. ft. higher, using the exact same ARP lube I'd used previously. And yes, I know that the threads probably had to burnish in which would account for an increase in torque, but I didn't trust using the original bolts after that many reuses. It was cheap peace of mind. I will say, when done with new bolts, the final torque value after the TTA process is very close to to the 65/55 lb. ft. recommended.