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ARP Head Studs - 4.0/4.6 Engine


garrycol
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I am building up a 4.6 engine out of a 4.0 block and heads. I have put in ARP head studs but am getting conflicting information on what torque to use on the head nuts. The ARP instructions says torque them up to 100 ft lbs but most people I have spoken too believe this is too high. The standard bolts used in the engines are of a stretch design so use the torque and the then turn through a set amount of degrees to torque which is not relevant to studs.

So any one who has used ARP studs on your 4.0/4.6 what torque did you use and how has it worked out?

Note: information on the 3.5/3.9 engine is not relevant as these are torqued lower than the 4.0/4.6.

Thanks

Garry

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I have not used ARP studs on that engine but from what I can tell you, follow what ARP says. We have built many BMW engines which we turbocharge and trust me, we torque them a bit higher using MLS gaskets and these engines are running trouble free.

You must follow the ARP torque sequence using both a torque wrench and in most cases an angle gauge which fits the torque wrench, 1/2 inch drive for the most part.

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Yeah, the given figure is ridiculously high. Since it's finer thread than the original bolts, even the standard torque figure has more clamping force with ARPs than with the standard bolts.

IIRC the standard torque figure is what we used, and also what was recommended by an engine builder.

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Yeah, the given figure is ridiculously high. Since it's finer thread than the original bolts, even the standard torque figure has more clamping force with ARPs than with the standard bolts.

IIRC the standard torque figure is what we used, and also what was recommended by an engine builder.

Thanks - but what is the standard torque figure as there is no figure for the 4.0/4.6 engines.

With head bolts the torquing process is :

1. Torque to 15 ft lb

2. Turn 90 degrees and stop and wait a bit , then

3. Turn a further 90 degrees

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I put a set on my 4.2 using 4 studs per cylinder like the 4.0/4.6 and I torqued to the same specs as the non stretch bolts.

Reason being they don't stretch so if they were to be angle torqued you would end up with a rediculess torque figure and possibly pull the threads out of the block.

Also the moly lube build past allows the nut turn more and give a higher torque figure than building dry due to having less resistance on the threads and nut base.

70 ft lbs seems to be about right and what I torqued mine up to.

http://www.v8forum.co.uk/forum/viewtopic.php?t=9647&sid=583f2c8f70f2659442da9cd2df201151

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I think the 3.5 / 3.9 torque is a fair torque setting, because there isn't any real difference between the engines. I mean, we arn't talking RV8 vs Duetze air cooled diesel vs CAT C4.4 ?

I did my 3.5 to ARP settings on mains and heads and that is flippin' tight. As mentioned you get the higher torque and it has greater effect due to finer thread.

So I would go with standard 3.9 settings and if it is the correct studs for the 4.6 block I would go to the ARP setting. (There was issue on this forum with 3.5 stud kit in a 4.6. Pulling the threads out of the block was fixed with helicoils)

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Thanks for the commentary - the 3.5/3.9 has a lower torque setting than the 4.0/4.6 so while the 70 odd lbs for the 3.5/3.9 may work, it may very well not last once the engine is up and running.

The studs I have are the correct 4.0/4.6 studs for the engine not the old Buick 215 studs that were used in the 3.5/3.9 engine.

The specified 100 ft lbs seems just too high and the block (when owned by someone else) already had a previous head bolt pull out using the above torque method for bolts. This hole has been repaired with a helicoil but all the experts seem to think 100 is too high and maybe 90 would be better but I have not actually found anyone who has used the ARP studs on a 4.0/4.6.

I have emailed ARP a couple of times on this but have never got a response.

Cheers

Garry

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Thanks for the commentary - the 3.5/3.9 has a lower torque setting than the 4.0/4.6 so while the 70 odd lbs for the 3.5/3.9 may work, it may very well not last once the engine is up and running.

Cheers

Garry

Do you mean torque settings for the OEM bolts or the ARP studs?

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Yes. Or do you have me on ignore by now?

Just torque them to 70.

Sorry - not ignoring at all but your above post is the first indication that you personally had used them on a 4.0/4.6 - your previous information came across as general advice not necessarily based on personal experience which is what I am after. Often advice is provided on forums in good faith but is often not based on actual experience.

So when you built your 4.0/4.6 you torqued them to 70 ft lbs and you have had no issues with head gaskets etc

Cheers

Garry

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Sorry - not ignoring at all but your above post is the first indication that you personally had used them on a 4.0/4.6 - your previous information came across as general advice not necessarily based on personal experience which is what I am after. Often advice is provided on forums in good faith but is often not based on actual experience.

So when you built your 4.0/4.6 you torqued them to 70 ft lbs and you have had no issues with head gaskets etc

Cheers

Garry

Not mine personally, but a friend's which I helped build. A few months ago.

It's still going fine.

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Not mine personally, but a friend's which I helped build. A few months ago.

It's still going fine.

Actually you helped 2 friends build their 4.6 with ARPs. ;-) And a customer.

I do remember using 70 and torquing in 3 steps on mine. Ran fine for a couple of years until I decided to #### with the engine management... :-(

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