Technical Service Bulletin Replacement Pistons

Subject: Replacement Pistons       Models: 911/930 1980

Bulletin Number: 81 – 01

Beginning with 1980 models, factory-installed pistons have a weight differential of 4 grams max.

Weight identification is stamped in top of piston (-. –. +, or ++).

For replacement, however, weight differentials up to 8 grams are allowed.

Piston, Replacing

Only two piston weight classes are available for replacement of the four weight classes used in production. Therefore, pistons with – and – identification marks take one class and those identified with + and ++ take the other class for replacement

Note:

Early 1980 models and before had no piston weight identification. When replacing pistons in these cars:

  • Weigh piston, together with rings, wrist pin and wrist-pin lock rings
  • Find weight class from table (p.2)
  • Obtain pistons by part number given in table (or consult your Parts Department)

Pistons, installing

Two manufacturers, Mahle and Schmidt, make Porsche pistons.

  • Install pistons of only one company in any one engine
  • Install pistons of only one weight class in any one engine
  • Install cylinders (pistons and cylinders available only as sets) of same height on one side of the engine (see mark 5 or 6 on side of cylinder wall as shown)

Replacement Pistons                                     Mahle Pistons

Part No.
Vehicle/engine typeWeight/identification mark {on piston heed}  Piston with cylinder {Gr. 5}Piston with cylinder {Gr. 6}
911 SC, 78/79 models USA/Calif. -930/04/06   911 SC, 80 models only USA/Calif. -930/07No specifications   660 – 668g – – or – 668 – 676g + or + +   No specifications* 636 – 644g – – or – 644 – 652g + or + +930.103.962.01 N/A 930.103.962.03 930.103.962.04     930.103.977.01 930.103.977.03 930.103.977.04930.103.962.02 N/A 930.103.962.05 930.103.962.06     930.103.977.02 N/A 930.103.77.05 930.103.977.06
 *Some early 80 models were built with pistons having no weight specification. If these need to be replaced, pistons with weight specification can be used.  
911 Turbo, 78/79 models
USA     -930/61 Calif.    -930/63No specifications   601 – 609g – – or – 609 – 617G + or + +930.103.969.01 N/A   930.103.969.03 930.103.969.04930.103.969.02   930.103.969.05 930.103.969.06
                                                                                     Schmidt Piston
911 SC, 78/79 models
USA/Calif. -930/04/06    No specifications   695 – 703g – – or – 703 – 711g + or + +930.103.966.01 930.103.966.03 930.103.966.04930.103.966.02 930.103.966.05 930.103.966.06

home page: klassikats.com

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