The V8 Owners Forum -

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helicoils or timeserts would do the job. As to why your not supposed to do studs in stages, you snug them all up and hit the final torque in one hit. you get a lot of stickshion doing it the way you did even with the lube on. Probably doesn't explain what happened tho to be honest as that would usually leave you with an under torque. Did you bottom the bolts out on the block? did you use lube on the block threads? If you bottomed the studs and used lube its possible the stud turned into the block and if the bottomed it could push the threads out. Other reasons was it was just a bad thread, it happens. All just theories I am afraid but some possibilities in there for you.

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ok another theory, you put too much oil in block holes and hydraulic locked the bottom of the threads. That will pull the thread every time as there is a hell of a force when you do that. Sound possible?

I vote for the oil in the hole theory too. Very easy to do.

I have to add that Timeserts are brilliant things. The exhaust bolts on my TVR heads are held on with LOTS of these...

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The slip I got with my ARP studs said to do them up in 3 stages.

I also stripped 2 threads but they was suspect to start with.

I heli-coiled them and after that they was fine.

I did choose to use an in-between torque of the rover torque setting and the one that came with the ARP Studs. I think I did them at 70lb

I also used moly lube.

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blknight05 wrote:sorry last reply was wrong topic,
so you did them up to 70 i got to about 60 and thought god this feels abit tight thats when the thread went,
im abit nervouse now about going much above 60 although i think alot of people on here do their arp head studs up to 65,
iv got the heli coil kit now im just worried once iv done it another thread will go then its al got to come apart again to do that,iv been told that the most common one to go is the center thread or number 1 on the tightening sequence which is the one that went on mine so fingeres crossed the rest wil be ok.
do you have any tips on doing the heli coil as iv never done one before?

not 100% sure I went to 70 or 65. would need to check my notes.
The centre one was already very bad so that was changed, before I'd started.

but the ones either side went. if you have them and have the time, then do all 3. on both sides.

We found you could drill the block with the drill bit in a large tap holder and drill it by hand. we did this with the head on, and tape on the drill bit (to stop it catching on the head). this kept the drill bit straight.

you also may want to make a tap guide to make sure it goes it straight, unless you have tapping machine.

katanaman wrote:ok another theory, you put too much oil in block holes and hydraulic locked the bottom of the threads. That will pull the thread every time as there is a hell of a force when you do that. Sound possible?

What does the stud torque against, if not the bottom of the block? Do they have a shoulder round them they torque down onto? I know you should never torque a stud down to the end of its thread, as that can crack the stud with localised stress on the thread, but bottoming out in the hole should not strip the thread in the block.

The stud is supposed to be screwed into the block hand tight. it doesn't need to be bottomed out. It's got a coarse thread so once it's under tension from the nut which has a fine thread it shouldn't turn. It should become at one with the block.

Having said that there are studs and there are shouldered studs which work differently. Arp sometimes list different torques depending on the block material, iron or aluminium as well as whether the lube is oil or moly. If the thread strips then there was either a naff thread, hydrolock, oil lock or the instructions weren't followed out correctly. I've never had a problem with arp's so would say something was wrong somewhere.

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It's probably safe to assume that rover block threads may be a bit worn if the engines been apart more then once.

I had this same problem when I built my last engine.

We put it down to worn threads in the block but were never 100% on that.

I had to heli coil a couple to get around it but I wouldn't use studs again though but instead use bolts from arp.

If you helicoil them put two oils in the block as one won't cover the whole threaded part of the stud which would cause the stud to be pulling on even less thread. I still have a heli coil kit for the block if anyone wants it?

Pm me if interested.