So what should I tell the machinist if I drop off the bell? If the bell is 5.125 and the bearing is 4.8, should the ring go from 5.125 to 4.799 to allow for some interference? Of course Brewers doesn't have one of their adapter rings listed for this application....
Your machinist shouldn't need the bell at all (unless you need him to verify that the hole is slightly larger than 5.125". You can do that with a dial caliper. Bellhousings are heavy to lug around ;)
Just bring him the retainer and tell him you want the OD with the adapter ring installed to be 5.125. The retainer OD should be exactly 4.805, so the ID of the adapter before pressing it on would be about 4.804...
