On a previous thread I was having problems with cam bearings wiping out on an FE 390 stock rebuild... I have looked everything over (cam rotated freely, no missing oil galley plugs, main bearings appeared fine, rockers were getting oil) and had good oil pressure(30 hot) throughout all of the failures. On the first two runs I had cam bearings installed at 6 o'clock (except first bearing) then on the last one I had the bearings located at 3 o'clock. All of them eventually failed with them being wiped. I had cam verified straight by a cam shop as well. Total run time between all this is maybe 6 hours, and went through 4 sets of cam bearings.. ouch.

The bearings have to be getting oil because the mains are, so my only guess is that the journals are ground wrong.

Have you guys ever encountered a situation where the cam journals were ground the wrong way leading to cam bearing failure?

 

I've never heard of it in this forum, but it's about all that's left to check, isn't it? How do the cam journals look? Can you take some pictures?

 

Good idea for pictures.....throw up some of the old berrins, too.

Do they look like the babbit layer got hot and melted covering up the oil holes?

 

Yeah it's pretty much the last thing that could be the problem that I know of.

Some of the bearings did have the oil hole covered with babbit, others not so much. However, what I find really strange is if they were starved of oil wouldn't the last cam bearing(the last to get oil), look the worst? Because it looks the best with very little excessive wear, no wiping really at all.

Here are some pictures, unfortunately I don't have extremely close pictures of the journals.

 

Sheesh! Don't think it's the cam journal's finish that's causing the problem....More like the heavy handed berrin installation.
One has to be fairly nice and sweet when beating those berrins in....Look at 'em closely....methinks someone beat the Bejesus out of 'em putting them in, causing them to be out of round and not square in the holes. A chamfered edge would be nice to see, but I don't see any.

A little carefull-ness and attention to set up would be in order on the next berrin install...............

 

Well the cam bearings did not look like that initially-these were all after the failure. They did not look like they were beat in to me. Could you explain what you mean a little more?

The cam rotated rather freely too every time. The first two failures the machine shop installed the bearings, and the last set I installed with a tool, and they still failed.

 

That bearing looks a bit beaten up or is that the babbit that's been forced off the surface of the bearing?

The pic of the cam looks like before it was even used - can you post pics of how it looks now? I'm thinking the original bearings were beaten in, and now the cam journals are too scored so it's a second failure. But I can't say until I see the cam as it is now.

 

I would have never installed the cam with bearings looking like that haha, I could barely get that cam out. Here's the bearings installed by the machine shop on the second go around. There were no visible signs of someone beating them in, or installing them improperly, from my knowledge.

They look beat because that's Babbit melted off of the bearing. The front one was almost to the steel, one little spot actually was.

 

Cam berrins get hot, from no oil, excessive journal run out, or even spinning (a little) in their respective bores. Hot + no oil = melted, etc.

I think the next step is to mic the block's cam berrin holes, and the the outside diameter on the new berrins....and the cam journals. Well, put the journals in a coupla 'V' blocks and check for run-out.

 

It's not safe to assume but from what I understand this is a rebuild, and if it ran for years before rebuilding I wouldn't think the block would be a problem. Bearing look to be installed correctly, I'd be concentrating on the cam.

 

Sounds like we are on the exact same page. Before the rebuild, the bearings looked fine, so obviously the block was fine. So I am more than likely going to buy another cam and lifters, so I can completely eliminate it. I will be doing that today more than likely.

The cam was already checked for runout, at the cam shop and it was perfect.

 

Can you explain the 6 o'clock and 3 o'clock positioning of the cam bearings, that part's not making since to me.

 

The hole in the cam bearing has to line up with the main bearing oil hole in the block.

 

Basically if the oil hole is positioned at 6 o'clock the oil has a harder time overcoming the downward force of the camshaft, to provide an oil wedge between the bearing and camshaft. This means it may not get lubricated as well. Putting the oil holes at 3 o'clock means that the oil will come in on an unloaded section of the bearing, so the oil can spin around and form a better wedge of oil.

 

Very unlikely to be journal finish. But possible to have a cam bearing alignment issue and still be able to turn the cam. I believe that Ford installed cam bearings in a semi-finished state and ran a broach through them to bring them to size. We have found cam bearing bores that were an amazing .020 off center from the others in a block - no way it could have run on a standard finished cam bearing. Next ones you do try "painting them with some machinist dye and rotate the cam through a few revolutions - remove and check. I would not be surprised to find it contacting some bearing spots and not touching others. A straight cam with an inadequate .001 clearance will rotate as smoothly as one with .005...