Quote:
Originally Posted by TomCounihan
Great thread. One detail missing for me however - the torque.
Would I be correct in saying - for completeness - the permutations and torque values areas follows:
3.0 Case <-> 3.2 Cylinder <-> no gasket <-> 3.0 Heads = 25#ft (my config)
3.2 Case <-> 3.0 Cylinder <-> yes gasket <-> 3.2 Heads = 15#ft+90 degrees sweep
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I believe you have these backwards and the torque values are incorrect.
Check what Flat6pac (Bruce) says on the higher torque Post 2 of
3.2 cylinders vs 3.0 sc cylinders?.
Quote:
Originally Posted by Flat6pac
Didn’t you just ask him...
The difference is the sealing systems, head gaskets
The 3.0 uses an aluminum seal ring to the head.
The 3.2 uses a tapered edge and more torque to seal the head.
A 3.2 short stroke cylinders need to be opened to 98mm which leaves little support for the 3.0 head gasket, the 3.2 cylinder is preferred for the application.
I’d still ask him
Bruce
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TSB 8703 Tightening Procedure for Cylinder Heads, page 5, reviews torqueing of the Carrera heads, 911 cylinder heads up to 1983 Model Year and all 911 Turbos.
3.0 Case <-> 3.2 Cylinder <-> no gasket <-> 3.0 Heads
Step 1: Torque to 15 Nm (11 ft. lbs) in sequence.
Step 2: Torque nuts an additional 90 degrees.
I agree with Henry Schmidt that the Porsche head studs have issues.
I've used the
Supertec Performance Cylinder Head Stud Kit on two different rebuilds and think they are the best solution.
Edit
After the initial posting, I realized I was guessing on which torque method had the higher final torque value. So to test it out, I used a M10 1.5 stud I torqued a nut to 11 ft lbs and then an additional 90 degrees using a deflector beam torque wrench. When 90 degrees was reached the beam torque wrench indicated about 85 ft lbs.