The 216's and obviously the earlier engines had that copper pipe through the water jacket. 235's with pressurized crankshafts and replaceable rod bearings took the valve train lubrication from the rear cam bearing area and fed it to the center of the rocker arms. I'm pretty sure the line material changed to steel once it didn't have to be exposed to the coolant.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!