The V8 Owners Forum -

Hi Ladies And Gents,
I am sure this came up a number of times on the old forum, but for some reason i cant get on there, what do you torque ARP head studs too (on a Rover 4.6 )? Both the iniatial fitting into the block and the torque down of the heads? I will of coures be using ARP stud lube.
Thanks For Any Advice,
Cheers John

John,

Presume you have the standard size 7/16 th stud set.

Real Steel catalogue says 65 lbft with ARP lube. I've only ever put the studs into the block finger tight after very carefully cleaning out the threads, never had one that wouldn't go fully home.

regards,

Dave

Same here.
I just put them in by hand and give them a little nip with the allen key. And I mean a little nip.
I used the ARP lube and both engines have been ragged beyond their recommended limits with Nitrous. Never had a HG failure.

davemgb wrote:John,
Real Steel catalogue says 65 lbft with ARP lube.
Dave

Really?

The whole point of the studs is to be able to get the heads down tighter. (No friction between studs and soft aluminium whilst tightening)

The torque setting for the bolts is 60 to 70 isnt it?

Not saying thats wrong, just suprised. I dont have head studs but my mains studs are set at 90.

ppyvabw wrote:

davemgb wrote:John,
Real Steel catalogue says 65 lbft with ARP lube.
Dave

Really?

The whole point of the studs is to be able to get the heads down tighter. (No friction between studs and soft aluminium whilst tightening)

The torque setting for the bolts is 60 to 70 isnt it?

Not saying thats wrong, just suprised. I dont have head studs but my mains studs are set at 90.

Yes and no, the advantage of ARP is they wont stretch and they have a fine thread meaning the torque applied is more accurate and it keeps the pressure on resulting in better clamping force. I cant remember what the rated torque is for the head studs but if you were to use it you could run a risk of pulling the threads out the alloy block. Like wise main studs, if you use full torque you really should get the mains checked as they are more than likely out of round. Same goes for rod kits as odds on they will go out of round. That said there is nothing new there as they go oval in normal use anyway.

Don't forget that the length of a fastener between the thread engagement and the head ( or nut on a stud ) acts like a spring. The advantage of the ARP studs is supposed to be better manufacturing quality control and better materials so they remain in their elastic deformation range - I'll stop before this sentence gets away from me !!...

A finer thread pitch is the same as a gentler slope - for a given force you can push more up a slope if it is gentler. The torque on the fastener can be less yet create more clamping force.

Regards,

Dave

Indeed but I also maintain that because when you tighten the nut up, there is no friction between the stud and the soft aluminium (Because they aren't in relative motion) thus reducing the likelyhood of the ally thread being pulled out the block.

It can happen believe me! My block lost 3 threads for some reason wen i used the arp studs.

out of interest, how many studs should hold the heads down (each side) in total?

I have some SD1 3500 heads, and it looks like there is a bunch of bolts missing to me!

Early heads had 14 bolts to hold them down but later ones switched to 10 deleting the outer most row of bolts. If your heads have holes for 14 then just use the 10 like the later heads (4.0 and 4.6 heads) you can put bolts in the oyuter row just to fill the holes if you like but only nip then up loosely or not bother with them at all like i did.

The reason for not using them is the pressure on the head is uneven as when using 14 bolts you have 9 bolts holding one side down and only 5 the other side which causes the head gaskets to blow on the valley side of the head.

Rpi have this coverd on there website which covers it in detail perfectly.

http://www.v8engines.com/engine-4.htm#gaskets

When you say you have a bunch of bolts missing do you mean you've bought a stud kit and it only has 20 studs in it or??

There's two stud kits, one with 20 studs and larger dia' studs which needs work to fit them to the engine or theres another set which has 28 studs in it which bolt straight in with no further mods.

Gav, as always, you a a feckin' star mate!

Nope, got ARP studs all round, just saw a pic of some engine and thought "crikey, there's about ten bolts missing here!"

Thought that would be another excuse to slap the Lund. Never mind, still got plenty left!


And by the way, the car is getting there! Nearly done all the spraying now (i hate glass fibre, its a bar steward alright to get done well!).

Still need to have a chat with you at some point r.e. Megasquirtythings Gav if thats ok, but no point doing it until next month when I have all the bits!

laters

No worries bud!

If i can help with the MS then let me know, i'll see what i can do!

Wheres the cheapest source for the ARP stud kits?
Best i have found so far is from the US at $151 + $45 P&P.

Hoss
If its a Rover V8, Real Steel ARP head stud kit is about 100 quid. So about the same as the USA price inc P&P.
What you need to do is find some guys who have bought the stud kits for the later heads. They will each have 8 spares.