re-using bolts in engine rebuild

[merc-blue]

So its a perormance build?? In that case ARP the shit out of it, big cost now but well worth it.
Also stud everything from starters to bell housings. make it all alot more "comfy"

[MX83-maybe]

sorry to hijack your thread but out of interest what do new head bolts go for from Toyota? I will be replacing a head gasket shortly on a 7M and am in the process of getting the Toyota EPC to find part numbers and so on... also wondering whether to re-use the head bolts?

[IN 05 NT]

ARP 7m bolts are $200 for the set (dont use toyota bolts on the 7m head)

i assume pubes rebuild is just a refresh... so re-using the bolts will be fine....

[jimmmayyy]

MX83, What he said ^^^

Don't use Toyota head bolts whatever you do!

Btw, did you get that gasket yet?

[EVOSTi]

4AGE head bolts aren't torque-to-yield and they are specified in angles after the first torque spec.

early 4age head bolts are not torque to yeild, later ones are. if angles are specified then its torque to yeild.

the initial torque settings tighten the bolt before stretching point, its the angle after that that stretches it.

how could you get an accurate torque setting if the bolt was stretching while you torqued it?

[LeeRoy]

I think your wrong, i rang toyota and asked them about whether or not the head bolts in my 100kw 4age (red top) were torque to yield and they said they werent, even in my service manual it doesnt mention replacing them.

[EVOSTi]

im positive the last one i rebuilt (gze) had TTY bolts, and it was done atleast 3 times ill check my manual tomorrow but im pretty certain, having said that ive been wrong on many occasions

[DX20VT]

I know all the 20V's are torque to yeild head bolts.

And I use a new set of genuine toyota head studs every time I pull the head off it.

I would also never re use a set of toyota rod bolts, ARP yes, but genuine no.

I have personally bought 4 motors that have tossed rods related back to s/h rod bolt failure,
mostly GZE's.

[Billzilla]

Guys: weigh up the cost of new rod bolts (about $70) verses the cost of the engine cutting itself in half.

[allencr]

http://www.boltscience.com/pages/tighten.htm

TTY is a bolt design that is usually tightened by the 'Angle Controlled Tightening' section in the above URL. This tightening method is also used on many fasteners THAT ARE NOT TTY design bolts, and Toyota head bolts are definitely not TTY! If those that claim Toyota bolts are TTY had actually ever seen or used a TTY, they might know better.

One is a specific fastener/bolt design and the other is a tightening technique that may be used on all bolt designs.

[Ben Wilson]

the initial torque settings tighten the bolt before stretching point, its the angle after that that stretches it.

how could you get an accurate torque setting if the bolt was stretching while you torqued it?

You can stretch a bolt without reaching it's yeild point, theoretically you should be able to stretch a bolt to just below its yeild point many times without any loss of strength.

[LeeRoy]

Correct me if im wrong but theoretically applying any force on a bolt should stretch it - even if only the most insignificant amount.

[Ben Wilson]

Exactly, there is a big difference between stretching and stretching to yeild.

[EVOSTi]

maybe im wrong then, i was under the impression that if after the torque sequence there was an angle tightening sequence then it was TTY. ohwell.

[duff_boy]

Well i work at cummins diesel and i rebuild diesel engines all day long. In the case of these big engines you _never_ have to replace the bolts at all, unless the thread is fucked out or(if you can be bothered measuring them) they are stretched beyond the given specified length. Type of tightening method doesn't really matter tbh, infact most of the important ones - ie mains, bigend and head bolts - they're torque + degrees method. Regardless of the bolt being old or new, they're tighten to the same torque. They seem to withstand several builds no worries, even when they're tensioned to 300ft/lb + 90degrees in some cases.