With the new fixture plates comes remeasuring of every critical dimension on the case, and if you don’t know much about Porsche cases its easy to imagine they are ultra precise pieces of automotive engineering. In some cases that’s true, in most cases however, the factory tolerances are quite amazingly bad.
Take for example the classic “118mm cylinder spacing” that has existed on every air cooled 911 case from 1965-1996. In theory, the cylinder spigots, no matter the year of the case or bore size, are supposed to be 118mm center to center. In practice, they are anything but, and as shown by our measurement of four different case halves there is a WIDE variance as to how far apart these cylinder spigots are actually located.
We measure these on a precision ground granite inspection plate that is certified for laboratory measurements. Then, we use a height gauge that costs over $1500, so our numbers are good. See our results for yourself, the variance is huge.
Ours of course will be perfect each time, because this dimension is easy to control.