Next we have to mount the block to the CNC milling machine. We have made up a custom fixture to mount the 944 block via the crank center line so that the boring will be exactly 90 degrees to the crank. On of the keys to long life of a performance motor is to get everything square. It would be easy to assume the the existing cylinders are true...but they usually aren’t’ - I have measured quite a few.
The CNC machine is programmed with the correct center to center measurements, bore spacing on a seasoned 944 block can be off as much as .004”, this is rectified in the MID installation process. The other key dimension is the depth of the machining - errors here will result in sleeve settling and head gasket failure.