Okay now bear with me on this one....is it prudent to change "only the main bearings" on this full pressured engine? The engine is 55' and has a lower end knock near # 6 cylinder. The mechanic pulled the ignition wires (one by one) while the engine was running and he tells me that this sound would have increased in sound if it was not firing, which he then implied indicated the noise was from the mains. Does this sound logical??? Also does one only replace the main bearings, or do the bearings come in sets which also includes the rod bearings? This here mechanic said that he thought the main(s) can be replaced while the motor was in the truck. the truck is a 47' 2-ton, with a changed engine.
