[Mk2] [Turbo] ARP head bolt torque settings

[theonetowatch]

Lost my manual on cd. Can anybody point me in the direction of this info for a Rev2? Quite like to get this together tonight!
Regards
Alan

[^Trickster^]

If they are head studs, put the stud in hand tight only, some people back it off half a turn, personal preference. its 60ft/lbs same as the main studs, I do mine to 65ft/lbs in about 3 stages, 25, 45, 65.

Make sure you repeat this proceedure 5 times, so you fully torque down the head, then following the BGB pattern for removal, but you only undo them all you dont remove them, then retorque again. Once you torque them for the 5th time, your done. This is to stop all friction etc within the threads. This was recommended to me by a engine builder in the states and after alot of discussion on the forums I emailed ARP who clarified this.

Then retorque each one individually after about 1500 miles - slacken it off, tighten the stud in again, relube the nut and washer and retorque.

Use loads of lube, all on the threads, under the nuts, and both sides of the washers

If they are actually head BOLTS like you put in your post, Im not sure.

Graeme

[kerazee]

Then retorque each one individually after about 1500 miles - slacken it off, tighten the stud in again, relube the nut and washer and retorque.

I have been informed that this is unnecessary and can be done on the first fitting by once the bolts are torqued up leaving them for 30 minutes (ie cuppa time) then going back undoing them and then retorquing them, by repeating this process about 5 times (with the 30 minute gap each time) prevents the need to remove the rocker cover after after the engine has been run in.

[^Trickster^]

This is incorrect information. They must be retorqued after 1500 miles due to cyinder head gasket crush, its not to do with the friction on the studs etc which is why the 5 times method is used. The 30 minute gap is also unneccesary. the reason you do it is to kind of polish the threads into each other.

Some people do get away without reqtorquing them later, however when running high power numbers which most people are when they fit arps you can get cylinder pressure passing into the coolant system and boil the coolant system because the head lifts slightly.

Graeme

[^Trickster^]

My email from ARP 2 years ago

Hello Graeme,

Good question. Each time you torque any bolt or nut, up to about 5
times, the threads of the bolt or nut are seating in to the threads they
are going into. In a sense "polishing" each other. As this "polishing"
takes place the friction between the two pieces is reduced giving you
more torque applied to clamping load vs overcoming friction. After 4~5
times the effects are minimal. Once you do this it does not have to be
done again during assembly. If you disassemble the engine make sure to
keep the nuts with the studs, matched sets. Five times is a great way
to go but most don't want to spend the time. The reality is that it is
working for you. Don't change what you are doing!!!

Typically we recommend a head re torque after a period of time. This is
not due to stud stretch but normally to head gasket compression and
everything moving around a bit after running. That varies with the type
of gasket. Many times the head gasket manufacturer will tell you what
is needed in the instructions. Also torque wrenches and people make
mistakes so it is a good double check. What I recommend is that you
back the nuts off, one at a time, about 1/4~1/2 turn and then pull right
back to full torque. If you do one at a time that prevents the head or
gasket from shifting.

If you have any additional questions please contact me.

Regards,

[kerazee]

That's fair enough, my information is from a fairly highly regarded MR2 specialist who has also debated the process with ARP and the idea of the 30 minute gap is to allow the crush of the HG, but as with every engine build people have different ways of doing it, and I was just offering an alternative.

Any how, back to the OP sorry I took this a little off topic.

[Steve Horrocks]

Same info I had Graeme, just re-built Andy Jones' engine using this technique (only 4 times though, gets bloody boring doesn't it?! lol)
Plenty of grease everywhere & re-torque after 1000-1500 miles.

Re-torqued mine at 1500 & they were all pretty even (tested torque before undoing & re-torqueing.

[^Trickster^]

LOL yeh it gets boring and its hard work when you dont have an engine stand, i had to hold the engine from twisting between my knees lol.

Plenty of lube certainly is the key, even when doing head studs haha.

I found some of the studs had backed off slightly when i retorqued mine.

Graeme

[Steve Horrocks]

pmsl @ between knees! nice one!

we did it in the car, sounds easy, then realise me torque wrench is nearly size of engine bay so can only get about 1/16 to 1/8 of a turn! lol!

[^Trickster^]

lol its great fun building cars isnt it!