I grew up around a very high-quality shop near the end of the era of the in-frame overhaul. A couple of situations contributed to that type of repair going out of style- - - -limited access to the engine due to the engines growing to fill all the available space under the hood, and the tendency for engines to wear out all over instead of being able to benefit from a "ring and valve job" repair. It was not uncommon to pull a 216 Chevy head, regrind the valves, replace the rings, adjust the rod bearing clearances, and reassemble the engine within the space of 2 or 3 days in the shop- - - - -total cost of less than $100.00, sometimes MUCH less!
About the time the 55 Chevy 265's started needing engine repairs, we ran into chronic low oil pressure problems after in-the-frame overhauls. Even replacing the rod bearings didn't seem to cure the problem. We found that the culprit was worn cam bearings which starved the rod and main bearings for oil. Replacing cam bearings required pulling the engine and a complete teardown. The Melling high-volume oil pump was still on the drawing board, which might have fixed the problem, but overhead valve V8 engines just wore out all over, rather than benefiting from a minor rebuild like the older engines. By 1958, it was virtually impossible to get the oil pan off most V8 engine cars without doing major surgery- - - -easier to pull the engine! Getting the oil pan off a 1970's era Pontiac required jacking up the engine, putting shims between the motor mounts and the frame, then unbolting the #1 main bearing cap and dropping it into the oil pan before sliding the pan off the crossmember.
Today's cars with main bearing girdle construction on the engines like most Cadillac V8's require splitting the block into upper and lower sections just to get to the rods to remove the pistons. That's definitely an out-of-frame job!
Jerry
