Technical Service Bulletin Crankcase Cylinder Head Studs

Subject: Cylinder Head Torque      Models: 911 Carrera 1978-1986

Bulletin Number: 86 – 13

The torquing procedure for  the cylinder head nuts has been changed as of production date June 30, 1986, from engine numbers: 64G07073 and 64H00089

Work Sequence:

  1. Torque all nuts to 15 Nm (11ft. lbs.) in proper order.
  2. Torque all nuts an additional 90 degrees in proper order.

The bearing surfaces of the cylinder head nuts and the threads must be coated lightly with “Optimoly H T”. Part Number: prior to any torquing.

This new torquing procedure can be applied to all engines from the model year 1978 in conjunction with the new cylinder head nut. Part Number 901.104.382.02 (yellow color)

Note: The new torquing procedure does not apply to 911 Turbo engines.

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Read about the progression of the 911 Cylinder Head Stud here.

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