Yes, and Yes. They do block off the holes to the cam bearings. Roller cam bearings are fine with the splash of oil from the rotating assembly so they do not need the pressure fed oil. Now that the engine does not need as much oil you can slow down your oil pump (if running a dry sump or external pump) to save HP. If you are running a normal wet sump system then you don't need to run a high volume pump therefore reducing drag just like with the dry sump.
Now you do need to have the cam tunnel bored for them which usually costs a fair chunk. Usually going to roller cam bearings you end up going to a big core cam (55mm or bigger) which helps reduce the cam twist and flex from big spring pressures. Most do not go this route unless they have already done every other trick to make power and still need just a few more ponies.
While we are on the topic, I have a question. Is anyone making roller cam bearings for standard Chevy cams?
PaulThey also greatly reduce the risk of spinning a cam bearing at startup in a big valve spring motor that has sqeezed every last bit of oil from the cam bearings because of the big valve spring pressure while the motor sat. Also, the elimination of 5 leaks in the engine reduces the amount of oil getting caught up in the rotating assy on its way back to the pan.
In regards to your final question in your post, the camshaft must be made from 8620 billet steel, or perhaps at least the bearing races. I would think that a standard casted chebby cam core wouldn't stand a chance.
By the way, did you guys know that this was originally a Ford item? Even when they first became available in GM-based performance blocks...if you went to the GM parts dealer, the guy behind the parts counter would hand you a part number and send you to a Ford dealership for the needle roller bearings...originally.
LO