ARP head fastener torque

[Don H.]

There is no flat on arp head nuts.

 

Yep -- ARP head nuts are 12 point.

[Guest ntc]

I give in

[Motorsport Mickey]

You're making this hard work guys, figuratively relax the fastening about one flat.

 

Apply a spot of Tippex (typing correction fluid) or other marker of choice on your socket and release the torque an imagined 60 deg, that'll do, you're only removing stiction.

 

Mick Richards

Edited August 5, 2017 by Motorsport Mickey

[foster461]

As always I appreciate the opinions and guidance. The hardest part for me is not converting flats to points but finding the courage to turn the torque wrench up to 110 lbs ft and hold my breath as I tighten the nuts, waiting for the stud to go PING or the block to crack.

 

Stan

[Don H.]

I can't imagine what it would take to snap an ARP stud, Stan -- it would be seriously high -- just look at the tensile strength of their studs. Now the block, however...

[Guest ntc]

As always I appreciate the opinions and guidance. The hardest part for me is not converting flats to points but finding the courage to turn the torque wrench up to 110 lbs ft and hold my breath as I tighten the nuts, waiting for the stud to go PING or the block to crack.

 

Stan

Stan

You are spot on,the studs will stand it the block will not.Never had to do it with arp nuts and studs and this includes race engines they are fit and forget.

[Motorsport Mickey]

I torque standard studs and nuts to 110 and I've had no problems. If you're worrying about the ARP because they are lubed then allow -15% off the recommendation because they will overtorque from standard. Should mean a 95 lb ft torque will give equivalent to dry fitting. Worst that will happen is a blown gasket.

Sometimes it's just easier to stick with the standard fastenings if you have doubts about the block.

 

Mick Richards

[RogerH]

Hi Stan,

the design torque is calculated to give a leak free joint.

The studs, for whatever reason, can get rather crusty and look as though they have seen better days.

The holes down below in the block should be quite clean (oily) and have no corrosion.

 

Fit new standard studs if necessary.

 

If you tighten to 105 and the holes strip their thread then you have found a weak point. Better to find it in the garage.

 

If you torque to a lower figure who knows what will happen; and it always happens far away from home

 

Roger.

Edited August 6, 2017 by RogerH

[Motorsport Mickey]

That's the trouble with lubed figures Roger, the lube increases the applied torque by reducing the friction.

I've always worked on a 15% increase in torque applied if you use a lubed fastening hence a reduced 95 lb ft lubed should work out to an applied 110 effect, therefore should still be the required head gasket clamp and within the block limits (according to me).

It may be enlightening for owners but non of my own engines have used any bolt products but Standard Triumph originals, works for me.

 

Mick Richards

[Charlie D]

Stripping a stud thread in the block is something that has always worried me, simply because of the hassle it would cause.
But has ANYONE ever actually had it happen?

A couple of months ago there was a discussion about how to remove a broken stud from the block. It wasn’t a stripped thread, the stud had snapped.

I forget who started it, but it was a lengthy discussion and eventually, if I remember right, the person decided there was no hope and would scrap the block.

If he still has the block it would be an ideal opportunity to see “how far you could go”.
He has 7 stud holes to play with. Would be an interesting experiment.

Charlie D.

[RogerH]

Hi Charlie,

over the last couple of years there have been at least two threads (that's topical) about broken studs deep down inside.

 

Both were repaired by the owners and had helicoils fitted.

The fact that it is deep down doesn't stop a repair being done - but it is a big hurdle.

 

Roger

[Motorsport Mickey]

"But has ANYONE ever actually had it happen?"

 

Yes, winter of 1987 when developing the first offset cylinder head, but I was seriously abusing the block ie moving the entire set of studs 3mm sideways in the block, after blanking off the holes and sawing off the studs.

 

Mick Richards

Edited August 6, 2017 by Motorsport Mickey

[Charlie D]

Mick,

 

“…winter of 1987…”

Obviously a memorable occasion!

 

Hmmmm….

Surely, if Triumph meant to allow people to offset the cylinder head they would have made the holes in the head slotted.

(Or you could have done it yourself with rat-tail file, and a little patience.)

[Motorsport Mickey]

“…winter of 1987…”

 

Obviously a memorable occasion!

 

 

Definitely so Charlie, that gave us a major step forward in TR engine performance, nope Triumph didn't "do" nonstandard and alter major engine components just so you could win races with them !

Kas Kastner the US Triumph competition manager in 1962 had already been there asking ! he did manage to get a small batch of TR heads "reimagined" by the Triumph engine suppliers with the "squish" area made considerably thicker which made compression ratios over 12:1 a lot easier to machine into them. Shame he couldn't get the valves and combustion chambers moved as well, it would have saved us having to move them afterwards !

 

We made the choice of blanking off the cylinder head stud holes in the block with specially made cast iron material studs as close to the block material as we could, bonded with Loctited 648 in place. Then redrilling the block for new head stud holes 3mm further across therebye moving the valves away from the liner bores was made in preference to slotting the cylinder head, because we didn't want to risk any "head squirm" and movement of the head in use. Although we theorised about sliding a 3mm pin or "segment" behind the stud when fitted as far as we knew nobody else had done it and so we couldn't ask ! and we felt that the more difficult way of moving the head would be the most reliable. I understand that certain other competitors that have copied the moved head have slotted their heads and some have suffered with gasket problems although Teriann in her head review is misinformed (probably deliberately) when she says moving the head only gives minimal gains. http://www.tr3a.info/FAQ_heads.htm

 

Certainly the head move was reliable with us, I won the Championship with that engine in 1988 and in 1989 after I'd sold the car to Grev Watson I reworked the same engine with it's moved head and Chris Conoley drove the car 1235 KY to another Championship win as I reworked a TR7 V8 into a Championship winning package.

 

The TR4 has subsequently been sold and still with the identifiable engine (now updated I think) with moved head I saw it win a 60s Classics race at Donington about 3 years ago, still a fast car.

 

Mick Richards

Edited August 6, 2017 by Motorsport Mickey

[Guest ntc]

Nice one Mick Have you seen the latest 6 pot block/crank with equal spacing between cylinders ?

[Motorsport Mickey]

No, sounds interesting, I'll PM you to prevent more thread drift.

 

Mick Richards