Originally Posted by 00bonnevillessei
If you change cams and the internals , do you have to change the oil pump?
If you have the pan off anyways, then at least check it for clearance inside. On engines with conventional distributors I usually replace the pump anyways or at the very least the collar on the drive shaft. (only because the distributor is driving the oil pump and a worn oil pump effects the timing.)
Like the fellow mentioned, if you blew a bearing in the motor, replace the oil pump. In fact, tear down the engine completely and clean out all the passeges in the block, crank, etc. Those metal chips get everywhere...no sense replacing the blown bearing if you are going to leave the metal floating around in the oil system to wipe them out again.
On a distributor-less motor that had no other wear issues, just inspect the oil pump and put it back in if good.
One other item is the oil pump drive gear. If you change the cam, replace the gear that mates to it with one of suitable material. As a general rule: steel cams get bronze gears, cast iron cams use ductile iron gears. (Check with the manufacturer of the cam as to which gear to use.) This is a long-term wear issue...most cast iron cams are like a tootsie-pop...crunchy on the outside, chewy on the inside. The soft iron gear is a nice, long wearing material. A steel cam is so friggin hard that it would break the teeth out of a ductile iron gear, so a bronze gear is used...it absorbs the impact of the steel teeth. Yeah, it wears out quicker but at least it doesn't break.