A couple of questions
 

1st Question:

This one really bothers me as I don't want pulled head studs like the guy om here with the 964 and ARPs.

What is the correct torque for the cylinder head studs ?

Wayne's book quotes 10Nm then 32Nm (23.5 ft-lbs)
Bentley's quote 15Nm then 90 deg clockwise, I tried this a few times and this comes out to 48Nm even with moly lube.

This is a huge difference which is correct ?

and just to confuse myself a bit more I am using ARP studs and the box says 49Nm (36 ft-lbs)


2nd Question:

Spring height,
Wayne's book quotes 34.15mm to 34.45mm
Bentley's quote 34.5-0.3 mm does that mean 34.5 to 34.8 mm or 34.5 +/- 0.15 mm ???

I measured all mine using the welding rod method and they are all 34.45 to 34.6 which is right on or above top limit in Wayne's book. Problem is if I add another shim (0.5 mm) they will all be below bottom limit. :confused:

HI quint22cp the headstuds I would use the instructions in the ARP box for there torque settings, what cams are you using ??if there STD then the spring hights for a SC is 34.5mm IN and 34.5mm EX and a -0.3mm.

regards mike

I'm not an expert on ARP studs but they maybe quoting a generic torque for headstuds on any engine instead of a specific Porsche aluminum case engine. Personally I'd use the Porsche spec unless I got several opinions of using a higher torque from knowlegable engine builders like Steve and Henry. The consequences of low torque aren't as severe as the consequences of over torque.

The spring height question I'm also not an expert on as I get my heads done by someone other than me but the numbers you show look like they agree pretty closely with each other. 34.5 -.3 gives a range of 34.2-34.5 which is about the same as Waynes numbers.

-Andy

Did you ever get your answer regarding the correct ARP torque specs? I'm in the same boat and am unsure what to use.

Let me know. Thx

I went with the 32Nm (23.5 ft-lbs) Wayne's book quotes after reading a post on here from a guy with a 964 who had pulled ARPs. My guess is his engine was built with ARPs torqued up to ARPs spec' and that's what pulled the threads out when it all expands.

At the end of the day the ARPs are just a good bolt but the thread in the aluminum case is still the same and the weakest point.

I haven't got the engine back in yet so I cant report a success or not.