The original equipment oil pump on the 265's had very little reserve capacity, and the Melling high volume pump didn't show up until the mid-1960's or later. When the 55 -57 engines got enough wear to need rebuilding, Dad's shop did a few "in the frame" ring and rod bearing jobs like was a routine fix on stovebolt sixes. Almost every one ended up with a flickering oil pressure light at hot idle, particularly on automatic transmission vehicles. He finally rigged up a remote oil pump in a 5-gallon bucket, removed an oil pan and put a big catch pan under the engine, and had me run the pump with a drill motor while he and his partner watched where the oil was going. The worn cam bearings were squirting massive amounts of oil. After that, they refused to do any more "in frame" rebuilds- - - -pull the engine and do the whole job the right way the first time! The load on the cam bearings on the V8 was causing wear that the sixes didn't experience, and that was causing the low oil pressure.
Another quirk of the 265's was the distributor. It had a flat spot machined in the housing that allowed oil to get past the distributor and fill the valve lifter galleries. If the distributor was installed in the wrong position and the plug wires were walked around the cap to compensate, the housing would cut off oil flow to one bank of lifters. Later model distributors had a full-circle groove instead of a flat spot on the housing.
Jerry
