I dont know, but here is a tale involving a similar happening.
Back in high school a buddy and I swapped out cams and their lifters. His was a stock hyd setup on a '57 140 hp 235, and mine was a stock solid setup on a '59 261 truck motor. After we did the swap immediately both engines began to blow blue oil smoke out of the tailpipes.
I thought the quiet hyds were nifty ('cept for all the oil smoke!) He thought all the lifter racket from the solids (as well as the oil smoke) would surely drive him bananas. So after a short few days we gladly went back to our original setups. And both our oil problems went away!
Never seen anyone else try this, and never knew what caused it. The hyds needed oil to operate and the solid setup were empty hollow lifters with solid round bar pushrods, perhaps the lifter galleries are drilled or sized differently to suit the specific cam/lifter. The hyd motors suffered a higher rate of burnt valves than the solid lifter motors. But the hyd lifters are sure nice and quiet.
Tony P, have you ever swapped lifters between the various blocks ?
As I remember, the 235 pass PowerGlide engines had hyds and more hp than the solid lifter std shift engines from 1950 through and including 1956. In the 1954 and later motors, the camshaft bearing dias increased ( maybe the solid shafts were increased to match the hyd shafts), and their material changed- such that prior to '54 the cams required the solid tappets to be chilled iron, '54 and later solid lifters needed to be a hardened steel material, also McGurk warned of the need to also use the correct distributor drive gear material to prevent them from ruining themselves as well as the cam. This is especially important when attempting to use a reground cam- what year or material is it ground on?
Lots of blocks have a year stamped/cast on the inside of the crankcase (true at least on 261s)
Ed
