The V8 Owners Forum -

Hi All,
as a follow on to my post about head sizes and thicknesses when replacing on older block, could I ask for information on the need to torque and re-torque head gaskets? I've seen a post on the Mini forum that talks about cycling the ARP fasteners 5 times before final torque is applied, but my query is also regarding re-torquing the gaskets after a period of time? Has anyone got any thoughts on this javascript:emoticon(':?:') Normally once on there's a lot of ancilliaries that would need to be taken off again to get to the headbolts/ studs.
Thanks

Not that the heads stay on too long for us, but we use ARP fasteners with the lube that ARP provide, torque them up in three stages and forget about it. We have always done this from starting with the Rover tin gaskets and now with copper head gaskets. Zero problems. ARP stuff is good, follow their directions and you will be fine.

Alan

Same as Alan!
I just torque the ARP's down in 3 stages and leave them alone after that !

i do exactly too

Hi all, thanks for the replies. This question came up as I've just taken a head of a car and theres definite signs of leakage to the point where the gasket has nearly failed by No6 and is letting by between 2 and 4. The ARP studs were nipped into the block but obviously somethings amiss. So I guess the next questions are: Studs into the block - how tight is hand tight? Should I ( after a head skim to ensure the heads are flat), torque it up, leave it for a week and then re-check?
All answers are gratefully received!
Thanks

With critical apps like this, the fixings would normally be tightened (to the factory settings) until the bolt or stud stretches slightly - but still within its elastic limit. So unless something is moving - like the gasket compressing - there should be no need to check the torque at a later date. Indeed the original spec for the RV8 with steel gaskets involved the use of a thread sealer/locker, so any attempt to tighten it would break that seal.

ARP head studs only need turning in finger tight. I always give them a very gentle nip with the allen key though. Make sure that the bolt holes are perfectly clean and free from crud and especially any oil. You can nip them in with loctite if you so wish. Then make sure the washers go on with the chamfer upwards (if you have chmfered washers) Then use ARP assembly lube on threads so you have a bit of lube between nut and washer.

7/16" studs can be clamped to 70-80 ft/lbs depending on the exact kit you have. I set mine to 70ft/lbs.

Your leakage couold indicate that block and or heads are not flat. Or you may have pulled a stud thread in the block?

ARP studs should not be installed tight at all.

Nip them up by hand, then back out so they are loose in the hole. They are never supposed to be installed bottomed out.

And cant say Ive ever needed to "cycle" them either. Just torque them up in 2 or 3 stages and you're good to go.

Thanks all, please keep your opinions coming, I've stripped the heads and the offending drivers side is showing some signs of wear, so a skim is definitley in order. The gasket was almost burnt through at 6 and leaking between 2 &4! Nice tell tale bluing of the exhaust manifold gasket at 6 which I missed completly. Seems that some nip the studs up tight and some leave them finger tight but you all seem to be having sucess so I guess its not that critical - obviously though not torquing them as this may stress the block. Thanks again

I think that if your engine produces decent combustion pressures such as when you are using NOS then the standard comp gaskets can fail, it happened to my lump with a 115 NOS shot on top of the 300 odd BHP that the lump makes anyway. The reason for the failure is the huge chamfer at the top of the bores which leaves half the firing ring not being compressed, basically it is floating about in fresh air. I sprayed my comp gaskets with a copper/silicon spray which seems to have helped. The next time the heads come off I'll fit multi layer viton coated gaskets that Burton Power sell, they come with over size bore holes (96mm) which means that all of the fire ring is compressed. Dunno if you can get over size bore holes for the 89mm bore 3.5 lump though.

http://www.burtonpower.com/parts-by-cat ... uf=708&p=1

ARP studs can be torqued to 90 ft/lb if needed, we go to that figure, although the block threads need to be in tip top condition or they will fail, 70 ft/lb is probably the safest option. Whatever torque figure you use the outside row should be either left out entirely or torqued to less than 35 ft/lb, we use 25 ft/lb, enough so the vibration won't work the things loose. Studs should always be installed hand tight, a little nip to make sure they are fully engaged won't hurt. The studs don't bottom in the holes anyway, although John Eales sells special studs that fully engage and even fit into the conical part left by the drilling operation. From an engineering fundamentals point I disagree with his reasoning. Stock ARP fasteners work, they do exactly what it says on the box.

Alan