Yes I had to. The key is to find the exact center of the connecting rod. There are many methods out there for finding the center of the hole. I tested my procedure 2 or 3 times on piece of scrap aluminum to make sure each time I can enlarge the hole correctly.

Can you do it with a drill press? That I’m not sure but you must get the hole within .0001-.00005 under size to press fit the bearing in.

I started with finding the center of the hole. Then I used very sharp and short drill bit to make the hole a little larger in order for the boring bar to fit in. Then I started to bore out the hole using a very short boring bar in a boring head on the milling machine. The boring process will give you a very accurate result. When you are about .0001 -.00005 under, you can press fit the bearing in the connecting rod. So the problem with the drilling is that you may not be able get the hole under size to press fit the bearing. I think you should also check Ken Lambert web site. He has some nice pictures there for reference.

Once I test my engine and make sure everything is running ok, I will post more pictures and more of what or how I did it.

Borna