Help, I somehow spun the rear CAM bearing on a complete fresh rebuild.
I did NOT start the engine, just cranked it over and no oil cam to top end. Long story short I dismantled the engine and the rear cam bearing was stuck on the cam.

I do recall the I had to spin the cam with a wrench to get it to go into the rear bearing.


Question:

By not priming the oil pump would the cause the failure?


And advice would be appreciated.

The cam should spin freely by hand. It should not take a wrench to "work" it into the bearing. I would guess the bearing was too tight on the cam. I had this happen but caught it on the cam install. I had to have the engine shop shave the cam bearing down to get the proper clearance.

Rick

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2 Mopars come with Spark plug tubes. One is a world class, racing machine. The other is a 426 CI. boat anchor!

12.70 @ 104.6

That's bad news,sorry to hear that....unfortunately the slant six seems to have a tendency to do this on rare occasions....your not the first and probably not the last. Usually after the bearings are installed the cam is trial fitted and any high spots or misalignment is taken care of by scraping the cam bearings to achieve a good fit and allow the cam to rotate by hand.you can use a very thin application of some bearing blue,then fit the cam to help find the high areas,use a bearing scraping tool if you have one to remove the high area. Personally I don't use abrasive or sharp tools,the bearings are very soft... The good news is as long as the bearing hole in the block is still a good fit with the cam bearing all you need is a new set of bearings and make sure they allow the cam to rotate freely this time. For a little added insurance use loctite when they drive the bearings in....ma Mopar did some pretty rough machine work on some blocks and I've seen some holes look more like a fine thread than a smooth bored hole. Good luck with it!

It's not uncommon for long cam shafts like these and in other inlines to have a little runout, I've seen it in almost every instance even when new, and can bind when installed in the engine. Also, the bearing journal finish is also a lot rougher than it should be at times and needs to be polished better upon assembly, so you really have to determine which issue is to cause. And then there is of course the possibility of just a tight bearing, which is also not uncommon on most any engine after cam bearings have been installed, and would need to be addressed as well.

No, not priming the oil pump wouldn't lead to this as long as the journals were oiled prior to assembly. But since you observed it being tight beforehand, there are several other possibilities that need to be checked first.

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There's no such thing as too much cam....only not enough engine!