Leave it alone, you have the correct set up. In 59, GM made the last of the oiling improvements to the 235 and 261 motors. Oil to the rockers came directly from the galley instead of bleeding it from the rear cam bearing, they enlarged the metering orifice in the block that sent oil to the head and rockers, and pinched off the connector/overflow tube. What this did was create a sort of pressurized system. As for the rockers, 58 and earlier rockers had the oil groove on the inside of the rockers set up to intersect the dribble hole on the rocker. Because the 59 and up motors had this sort of pressurized system, GM moved the groove so that it was now offset from the dribble hole so that the rockers would dribble and not spit over the push rods and springs leading to oil starvation and no spring cooling. So if you have a later block and head, you want to use the off set rockers meant for that motor.
The drilled bolt, that is not a factory installed bolt. That bolt was one of two parts you needed to use if you were replacing an early short block with a later service replacement short block. There was also a plug or little cap that you had to use with the bolt. The cap plugged the larger oil passage in the later block, the drilled bolt redirected oil flow through the bolt to the rockers, and metered a little less oil to the the rockers. This was done so that you could use the later short block with an early head and rockers (with the centered groove in the rocker). That way you got the dribble you need for the rockers instead of spiting over the rockers.
The pinched connector was a feature of the 59 and up system, buuuuuut, thousands of earlier loop style connectors were almost routinely pinched off when either the port from the rear cam bearing got clogged, the rear cam bearing became so worn that all the pressure bled out around the loose bearing and no pressure to the steel tube that ran from the rear cam bearing to the center top of the block behind the lifter cover, or the tube just became restricted with build up and would not flow enough. The thought was to not allow any oil to drain away from the loop. So everyone pinched off, or cut off and squashed, the loop to try to maximize oil to the rockers in the earlier motors.
The clogged or worn cam bearing issue was also the genesis of the aftermarket copper tube kits that connected the oil galley at the oil sensor port on the driver side of the block, and directed it through a copper tube to the hex head fitting on the outside middle of the passenger side of the head. That port was a direct feed to the rockers. Some of those kits were just copper tube and some elbows. The best of the kits had an adjustable valve that allowed you to tailor the oil supply. Why? To keep the new supply from being too much of a supply and spitting over the rockers and soli springs instead of dribbling. You could actually adjust the external supply to get the feed to dribble.
Make sense? I think what I wrote makes sense but maybe not, lol.
Last edited by Dragsix; 01/28/2021 2:58 PM.
