[kwdiesel27]

History-late 70's 350 that has been rebuilt by previous owner. Details unknown, parts used, machining done, skill level, etc.... Had a bad cam when I bought the pickup. (73 chevy). Changed cam. Starts and runs good, oil pressure drops with temperature from 'bout 50lbs cold to nearly zero by 150 degrees. Then the top end starts rattling from the lifters losing oil I assume, runs rough, dies. I installed a stock replacement cam (I already had laying around) and timing set and speed-pro lifters. Have pulled pan aand changed oil pumps, actually used a HV/HP replacement pump. Now its about 75 cold and nearly zero still at 150 degrees. Where is it dumping that drastically? Block plugs loose? If so, which is most likey? Havent ran into this before, kinda puzzled. Any chance a cam bearing is slightly turned? Seems to be a good runner when cold and has good compression, just gota figure this out. Any help would be great.

[RPM]

It could have a spun cam bearing, but most likely you have too much main bearing clearence.

[bondo]

Ayuh,.......

It sounds like All of the Bearings are bleeding,.........
Profusely......

[machine shop tom]

You say it had a bad cam. If the cam had lost a lobe or lobes, the metal from them has gone through the entire engine. Probably messed up the bearings (including the cam bearings) and the piston skirts. There is no quick or cheap way to fix the problem.

Step one. Remove the hood.
Step two. Disconnect the battery.

Etc.

tom