Cam Bearings

[76GMC1500]

What should the journal diameter be on my camshaft? I tried to mock it up in my old block with my old cam bearings, but the cam's journals were too big. I measured them at 1.868"

This is in a 350 Chevy of course.

[76GMC1500]

This is an odd one. Turns out 1.868-1.869" are the acceptable dimensions for the journals on the cam. I measured my old cam and it cam out to about 1.859. I pulled the timing gear on the old cam and saw a 010 stamped on the fromt of the cam. Turns out the cam was ground .010" undersized and undersized bearings were used in the block. Kinda weird no?

[docone31]

I would have to wonder why anyone would undersize a cam. I could understand if it was 40yrs ago, and the cams were reground, rehardened, and tested.
I would have to wonder how easy it is to put that cam in, with the oversize bearings.
I bet someone here knows though. My thought would be, if the cam journals had scores sufficient to regrind the cam, what condition are the lobes in?

[techinspector1]

This is probably one of those screwups at the factory where the cam supplier delivered the cams with mistakenly undersize journals. I've seen original motors with undersize rod or main journals and cylinder blocks where there will be one piston that is 0.010" oversize, maybe because of a finishing flaw in that bore.

[76GMC1500]

Lobes are polished at the nose. The front journal actually had a small portion of the journal left at standard size so it would fit the timing gear. That step would have been hard to grind. The engine was probably rebuilt 10-20 years ago so they may have still reconditioned cams back then. No worries though, I have a new cam and cam bearings waiting to go into my block as soon as the machine shop gets done with it.