Hi K.H.,

There will not be a need to machine the case to install a 30mm pump. You will need to replace the four stock oil pump studs with longer studs. The easy way to do this is to take two 8mm nuts, install these on the stud you are removing, tighten the nuts against each other and turn the inside nut to unscrew the stud. Do the reverse to install the new longer pump studs.

Lastly, there are two different cam gears for a VW 1600 style motor. One has three rivets and the other has four rivets. This is important, because each cam gear takes a different oil pump. Make sure that the oil pump you buy matches the cam gear you have in your motor.

Good luck,

Andy