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Torque To Yield Bolts


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Must be a typo

76B1DC07-E229-4464-8E4A-3C310B646E4A_zps

Although ARP mentions using the "stretch method" for torquing the rod bolts if you have the proper tool (never seen one), the ARP rod bolts technically aren't TTY stretch bolts.

A TTY bolt is torqued beyond the state of elasticity and therefore undergoes plastic transformation, causing it to become permanently elongated. It can only be used once and then replaced. The ARP rod bolts can be re-used. If you look at step 8 of the ARP instructions, they only need to be replaced IF they become stretched.

Vida instructions clearly state to lube the TTY head bolts, and ARP recommending lube on there bolts supports that.

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Caution! Make sure that no fluids are present in the cylinder head bolt threaded bores.

The main purpose of making sure no fluid is present in the head bolt threaded bores is that if you were to install and torque a headbolt into a hole that was 1/2 filled with oil/coolant you stand great risk in either pulling the threads out of the bore or cracking the block due to the hydraulic force that would be caused by torquing said bolt into said hole with said oil/coolant which = very bad day for you.

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Has anyone above used studs on their engines? I have an S70 and want the new head to seal well. ARP (know personally) or other Brand Names you like?

Fourty years of engine building from B&S to Ferrari- I lightly oil the threads. Thanks for your info.! Derfly

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I would not use the head studs simply because you cannot (working) alone lift the head off without removing all the exhaust manifold studs first - with bolts, you just lift the head enough to clear the locating dowels & pull it up and forward off the block and manifold. Reinstall is also easier this way, IMO.

Head bolts hold up to at least 450AWHP :-)

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Interesting that you change the torque depending on the stretch of ARP rod bolts then ain't it Deimos?

And back to Jeff's post on not lubing head bolts...that's how they snap during removal and make noises that are sphincter puckering.

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Interesting that you change the torque depending on the stretch of ARP rod bolts then ain't it Deimos?

Despite us often referring to TTY bolts as 'stretch bolts' doesn't mean they're the only ones that stretch, all bolts stretch when torqued. What ARP is talking about there is not stretching them too much, not permanently stretching them, as they talk about making sure they haven't gotten longer when measured before re-installation.

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ohhh, forgot, never bought a single new head bolt...ever. They hold, get over it.

Get over what?? Actually they don't. Redblock head bolts I wouldn't hesitate to reuse - whiteblocks not so much. Eventually you will snap one off in the block.

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