potent951turbo

My cam tower has a slight leak so since there is no record of the headgasket ever being replaced I think I am going to go ahead and do everything while I am in there as preventative maintenance.

I just have a quick question regarding the torque sequence as listed on Clarks Garage. It says after the first step of 15 ft-lbs, the next two steps are 90 degree angle. Do I need to purchase one of those angle dials for my ratchet to achieve this? This didn't seem to be discussed in any of the head gasket threads that I found.

944 Turbo (86-89) M44 51-52
Step 1: 20 Nm (15 ft-lbs)
- - Step 2: 90° angle
- - Step 3: 90° angle

tommo951

Slightly different line to this question but I have ARP head studs and cometic Gasket what should I be torquing these down too and what routing should I use?

Cheers
Tom

hosrom_951

There are two types of torque angle tools, one is what you see on ebay (goes for $10 or so) which requires that the handle to rest on the head while torquing. The other is a magnetic type, which works better, slightly more expensive (like $30-$40).

Regardless, there should be a 10-15 minute wait between every torque step, and having the stock sud thread lightly coated with oil (they stretch). As for aftermarket ones, ARP recommends using stock value (mentioned in the archives), no locktite, but teflon tape to be used instead (someone chime in and comfirm this).

Tom M'Guinn

Raceware says 65 ft lbs (with a traditional HG anyway), but I've been going higher lately.

Re the torque angle tool -- I just use a cheap hardware store version -- no problems. In a pinch, you can just draw a line on the nut with a felt pen, and turn it a quarter turn, plus a smidge to be sure

Bri Bro

Both items should be supplied with the installation and torque instructions. If they didn't come with instructions, call.


You can get a Torque angle tool form OEM industrial (P/N 25424) from most part stores. You can also mark (Tape,marker,etc.) were 90 degrees is from your starting angle of the 1/2 drive handle.

Van

Hmmm... I just use a big *** breaker bar, and know that if it starts out point straight towards the nose, than I then want to be perpendicular to the fender... I've had good luck with that -- although I guess it's less precise than a torque angle gauge.

Ski

yeah, simple is to make a mark on the forward side of each nut with a permanent marker, 90° the mark is toward the front of the engine; next time, 90° that mark should be pointing toward the passenger side. For ease of use on this, I use a 12pt socket too.

tommo951

The reason I asked is that I know some people advocate torquing beond standard figures when running Cometic gaskets. Is Chris White or ST around for a heads up? Do ARP have the same stretch characteristics as standard? I would have thought not otherwise it would be a pointless replacement.

Ski

from PD website, just like P-car..

Torquing Procedure.

If unsure always use factory specifications. Inspect the Head studs and the Threads on the Stud and the Nuts. Inspect the Washers for marks and flatness. Use plenty of good Anti Friction Lubricant on the Threads. Remember any Friction here will affect the final Torque figure. Because of this, Performance Developments recommends the following Torquing values.

Fist Stage 20 ft Lbs, used to seat the Gasket

2nd Stage 90 Degree

3rd Stage 90 Degree. (stock studs)

Performance Developments also offers special Head Studs for these two applications. Please check under Engine Fasteners.

Chris White

Do not use the angle method on the ARP or Raceware studs – they have different thread pitch and they are not stretch type fasteners. Use the supplied torque steps (or you can go to a higher load). I have used as high as 100ft lbs (theoretical retention point of the block is about 115 ft lbs). I don’t think going much over 80 helps and it could possible distort the head.

Laust Pedersen

Wouldn’t it be interesting to know what the actual clamping force is?

Actually it shouldn’t be too difficult to measure. Just cut out a piece of pressure sensitive film (ref.1 and ref.2), put it under the washer for the head nut, tighten the nut to your favorite torque or angle (making sure the washer does not rotate), remove the nut and film, translate to color of the film to stress and multiply by the area of the washer. That’s the clamping force of a single head stud.

Then it may be a good idea to divide by the cross-sectional area of the stud to get the stress and verify you are less than 90% of the yield strength of the stud.

With this data we can actually compare the different torquing methods and the influence of the gasket type.

I am getting a sample of the high pressure film. If anybody wants to try it out on a standard gasket with standard torquing procedure I can supply you with a sample (of a sample).

Laust

Ski

that makes me feel better, I just did the track car head gasket, wanted to inspect the bores after more than three years and went to 72 on the ARPs. When I got to 65, it just didn't feel tight and my torque wrench just got back from calibration.

edit stock studs above, sorry.

toddk911

I also have ARP and Cometic MLS to be installed soon.

Was it Raceware or ARP that you have to re torque after heat cycle??? or both?

Chris White

Technically – anything with a stock (fiber) type head gasket should be retorqued.

toddk911

Chris: So stock is 65 but you suggest up to 80? Even with ARP?