Really ?!?! So what did the factory do, specify all cam journals be ground undersize? Or did they hone the bearings? Or did they just pound in the cams and hope for the best?
No, they didnt care. They would install the cam bearings and bore them out afterwards, so if they were off a touch, it didnt matter. The cam bearings were then bored straight, but the parent material of the cam bores wasnt necesarily straight! No problem till you went onto cam bearing set #2 of some pooor unsuspecting mechanic ....
Mikes way is the right way to do it, and not everyone CAN do it, so its a great idea if you can go that route. As far as cam journals go, its very rare that they are sized THAT much off, but yes, I can say its happened. I have some roller cams that I have taken to the crank grinder and had .001 taken off the journals, so it does hapen, but again, its very rare, and I'd wager 99% of the time unneccesary. Its almost always a bad bore job from factory, and quite often a bad bearing install by the shop, If they use a rubber style installer, if you dont keep it tight against the outer edge of the bearing, you'll most likely have an issue. I you have a aluminum solid spacer type, usually less of a chance, and I always put a wrap of tape around them, and they work out great.
This is absolutley a much bigger problem in BBM than the small blocks, but they have their issues as well. A lot of shops charge extra to put BBM cam bearings in, because they CAN be a royal pain. We also arent blessed with as stout of a bearing shell as say a BBC. I do a fair amount of Chevies as well, and there is never the prblems like there is with a BBM. That being said, GM did a lot of oversize and undersize stuff too. Just went to do some block work on a 400SBC, and the mandrel wouldnt fit thru the cam bores. Check the bore, sure enough, its undersized. So, its not just Mopars. The difference is we dont have all the over and under size ebaring options.
Also, one BIG area of concern is you guys polishing, cutting and scraping bearings AFTER the engine is partially assembled, or more importantly AFTER the blcok has been final washed. The lips behind a cam bearing hold a tremendous amount of grit and dirt. If your are doing this and the block has oil or solvent in it, your asking for trouble. Now I know, 28,000 people will come on here and say, " hey, I did it, and my engine is still runnning". I know..I know, but I am here to tell you, take a REAL good look at thos areas. They hold a lot of grit, and I have seen a ton of guys start up engines after they have done some work on them, and that grit is what killed them. Be very careful and clean those edges good. Carry on....
Pulled em out and installed a set of Durabond PDP-17 (uncoated) bearings after reading a couple other posts here. I used the same tool and method I had installed the others and cam slid right in with no clearancing whatsoever. My block was baked and heard that can add to the problem too??
polishing the cam journal is not the way to correct this.
you sold that Moostang and went back to some real muscle 
it will all come together 
you did try to slide just the front journal in without much luck 
