Let find me a cam!

[katanaman]

I think this thread is talking about two totally different kinds of cam. There are roller bearing cams where its the lifter that has a roller on the end (common on Ford and Chevy engines) and another type where the cam has roller bearings instead of plain shells in the block.

I don't get the advantage of running roller bearings in the block instead of shells, can someone explain what it is?

[russell_ram]

'I don't get the advantage of running roller bearings in the block instead of shells, can someone explain what it is?'

Reduced frictional losses - every HP not lost in friction is available to drive the wheels .

[kiwicar]

Roller bearings in block also mean less heat generated, so less cooling needed.
Also with roller bearings you need less oil flow, this, if you are using a belt to drive the cam, roller tappets and an all roller rocker system means you have to pump less oil to the top of the engine and scavenge less out (if using a dry sump set up). In theory less drag due to oil passing back to the bottom of the engine falling on the crank. All a case of improving output by reducing losses.
Mike