911 Case Dimensions (cylinder bore diameters)

[TurkTurk]

What is the cylinder bore diameter (some call it a "spigot diameter) in the 2.4 engine case? I am machining a case to accept 84mm cylinders. Thanks

[304065]

What you are talking about is two different measurements. The cylinder bore diameter is where the piston rubs. The spigot diameter is the inside case dimension where the base of the cylinder rests.

The measurement is called "Cylinder outer base diameter to crankcase"

2.0 (mislabled as 2.2 in the caption, nice proofing Dempsey!)
92.072-92.159mm (checks with spec book p. 27)

2.2 same as 2.0 (checks to spec book p. 39)

2.4 same as 2.0.

It's only when the 2.7 cylinders appeared that the diameter went to 97.072-97.152mm, or a 5mm change, basically.
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