Arp Head Studs And Cometic Head Gasket

[EVL-R33]

I just got the head off my RB25DET, and I purchased some ARP head studs and a Cometic head gasket (for a bullet proof seal ). I know the tensioning torque for the studs is about 108Nm for the nut, but does the stud itself have to be tensioned into the block? and if so, what tensioning specs should I use?

My second question is regarding the Cometic head gasket, do I need to use any type of sealants for it?

Cheers.

Edited November 25, 2008 by EVL-R33

[Adriano]

The instructions for the studs say hand tight, but i nip them up with an allen key.

[Angus Smart]

Search around

i do remember reading that guys dont do them tight in the block.

[EVL-R33]

Ah ok cool thanks, what about the head gasket, do I need to use some kind of sealant or just bare?

[Risking]

Through experiance Ive found if you hand tighten or more the studs into the block you will end up with small hair line cracks between the bolt hold and water jacket in almost every instance. (not instantly but over time)

I do them up till they nip up then loosen them off half a turn, with loctite the stud will stay in that position while you do the nut up. Leave the loctite 24 hours to do its job before doing the nuts up.

As rule I do this with every stud be it a main stud or head stud etc.

Also be sure to use the paste under the washers and under the nuts to ensure even tightening.

Leave the gasket as it is supplied.

In saying that about the studs in your application you may be fine hand tightening them but my oppinion remains the same about backing them off half a turn.

[anthonymcgrath]

hey guys hope you dont mind me reviving an old thread rather than just starting a new one and just being told to search lol!

I'm just about to tackle this job on my own RB25DET at the moment but I wanted to be sure I'm getting it all before I do...

So finger tighten the studs into the block. Use loctite to hold them in and allow it to set for 24 hours

tighten nuts up to 108nm (80ft/lbs) torque if using MOLY lube.

however I'm using oil so I read on this forum that it should be 135nm (100ft/lbs)

BUT do it in increments of 20nm in the tightening order specified (middle outwards)

halfway through the torque values I've been told to slacken them all off then re-tighten to correct torque - apparently this ensures a correct seating of head gasket and nuts? Can anyone vouch for this?

[GTR1993]

Through experiance Ive found if you hand tighten or more the studs into the block you will end up with small hair line cracks between the bolt hold and water jacket in almost every instance. (not instantly but over time)

I do them up till they nip up then loosen them off half a turn, with loctite the stud will stay in that position while you do the nut up. Leave the loctite 24 hours to do its job before doing the nuts up.

As rule I do this with every stud be it a main stud or head stud etc.

Also be sure to use the paste under the washers and under the nuts to ensure even tightening.

Leave the gasket as it is supplied.

In saying that about the studs in your application you may be fine hand tightening them but my oppinion remains the same about backing them off half a turn.

I was told this is a massive no no because you then have loctite between the threads rather then the stud onto the steel of the block when it is tight, Then when you do it up you can squash the loctite.

[snozzle]

hmm pretty old thread but im pretty sure u should do up the studs hand tight so they are just barely bottoming out, theres no point loctiting something if it isnt already tight, it will not do its job!

the more i think about loctiting those studs into the block, the more i want to cringe! defeats the purpose of moly lube there thats for sure - ive done as per instructions and never had a problem

[anthonymcgrath]

hey guys thanks for the fast replies - I know its late/early over there heh! Its 11am here in the uk.

so loctite is a no no - thats cool with me thankyou! I'll just ensure the studs are finger tight in the block.

the only downside is the previous owner fitted the stud kit, so I dont have the instructions otherwise I'd take them as gospel. I've had to take my cylinder head off to have it rebuilt. I've got it back now and my head gasket so I'm ready to go.

the studs are in the block at the moment and some feel quite tightly nipped up. It seems to need a 5.5mm allen key and I hilariously dont have one to loosen them off. I think they should be okay tho?

I'm going to put the gasket then the cylinder head on then get onto the ARP nuts torquing them up

feel free to cut me up guys I just wanna do this right ...I've been posting on skylineowners.com too.

[PM-R33]

Yep don't use loctite, just use the ARP lube.

Also for the headgasket I used ACL Hylomar spray to coat the gasket. Since it is an aerosol it's a piece of piss to cover the entire gasket easily.

Edited July 9, 2010 by PM-R33

[snozzle]

hylomar is good shit, we use it on diesel engines that also run metal headgaskets that have shit loads more compression than petrol motors

[anthonymcgrath]

well now you've thrown me guys - why is the aerosol stuff for the head gasket necessary? I was under the impression that it would just go straight on?

[PM-R33]

What brand of head gasket is it? Some don't require anything, but it doesn't hurt to put something on any way. Nissan actually recommend putting their Nissan gasket sealant onto their factory Nissan head gaskets but instead I used the Hylomar as it is easier to apply and from what I have heard one of the best things to use.

Personally no matter what gasket it is (maybe there is some exceptions), I usually apply a sealant for that extra help.

Edited July 9, 2010 by PM-R33

[anthonymcgrath]

its a cosworth 1.5mm head gasket for the nissan skyline. I didn't even know you could get them for it.

now I know about the head gasket sealant I'll definitely get some - hopefully shop near me will sell it

[PM-R33]

You know that will lower compression slightly?

I think going from 9.1:1 compression to around 8.6:1 compression.

Edited July 9, 2010 by PM-R33

[anthonymcgrath]

fitting a garrett gt3076 .86a/r. Engine is forged internals too 87mm pistons, nurspec conrods, calico bearings etc..

[snozzle]

i personally wouldnt run a 1.5mm gasket for that application - any reason as to why u were going with that headgasket? do you have a positive deck hieght slightly more than normal at tdc?

[anthonymcgrath]

1.4mm was on it previously but I couldn't get one. spoke to the guys @ RSP here in the uk and they said it would be okay with the turbo.