The new PB cylinder blocks are cast with no internal breather channel and yet have the boss for the external tube cast onto the outside. Simply boring holes into the crankcase will lead to oil loss and may compromise the internal cast webbing for the center main.
How have rebuilders modified their blocks to provide a working side breather? (Or are they electing to forgo the function of the breather entirely and have the side breather tube just for show......if that is the case, how well does the PB breathe at 6000rpm?) Many thanks in advance of your reply, Best, Chris
I can assure you there is no need for a second breather with good modern pistons. If you want to make the block look like a PB block just bolt the second breather onto the flange, as you say do not drill holes underneath it