When I did my in-place rebuild a number of years ago, I was able to remove all the shims on the mains without causing any drag. It would have been prudent at the time to investigate further, but I didn't. The 216 ran nicely and had no bearing knocks. however, after a few hours of running, the nice dry rear main area started to leak like a tap. A few months back I replaced the seal with one of the new type from Best Gasket (made from a teflon weave) and it held up great for about 100 miles. I had to drop the crank some to do the install and that included removing the transmission. Well, finally on my last attempt, I installed new main bearings as outlined in the manual. At the same time I installed an NOS rope seal. My shimming results showed that I had more wear on the rear most bearings. The rear main required about .002", that is .002 on each side and it progressed to the front main where I used .004" in shims or two .002 on each side. The seal has been very good ever since that repair.
My oil pressure really wasn't my main concern. On the highway at about 2200 RPM, I have a little better than 7 lbs pressure. I am using 20W50 and a 160 deg. thermostat. I know that pressure isn't stellar but it is OK. I think my cam braings are fairly worn but they don't give me any trouble. I treat the motor with the respect due to it's age!
