UPDATE: Cam bearing woes

[Pentroof]

Put the cam bearings in a 390 block tonight after finally getting it back from the machinist yesterday. Spent a couple hours cleaning it, even though I paid him to clean it. Just wasn't up to my expectations (you know, clean!).

Anyway, put #5 through #2 in with the oiling slot at 4 o'clock (actually, at 4:18 just to add fuel to the great debate). Put #1 in from the rear to help ensure it was in square. Verified the two oiling holes were aligned by reaching up through with a wire. Block was on a low bench at this point, so I could install the #1 bearing and then put the rear plug in before mounting it on my stand. My mistake was not grabbing my mirror and verifying before doing so.

After getting the rear plug in with a little green Loctite, I mounted it on my engine stand with the intent to install the cam next. Well, looks like I'll be ordering another set of cam bearings first. Weekend is shot.

A piece of the bearing surface to the rear of the bottom oiling hole popped out.



I didn't have any burrs on the block and the bearing looked very nice prior to installing it. Nothing evident on the tool and I'm very particular about loading the bearing and expanding the tool while full contact on the back of the bearing is maintained. I'm chalking this up to a bad bearing, unless someone has another suggestion on how I could have contributed.

[Pentroof]

Bearings are Dura-Bond FP-33

[Nightmist66]

Just curious how the picture was taken. That groove above the oil slot should be facing out toward the thrust plate. Not uncommon to see flash around the oil slots on new bearings. I just dress them carefully with a pocket knife.

[Pentroof]

Hey, thanks! You just pointed out what a complete F'ing moron I am  . Instead of realizing that slot is in the wrong place because I put the bearing in backwards, I thought the Babbitt had spit a chunk out next to the lower slot. Once fixated on that, I didn't even realize it's actually the bleed that's supposed to be facing forward from the side slot.

Since I installed it from the back, I Should have loaded it with the bigger chamfer toward the tool, and I didn't.

So......anyone have any luck removing and replacing a cam bearing?

[blykins]

Yeah, no problem.  Just knock it out and put it back in facing the correct direction.  Since you have green Loctite handy, dab a little on the bearing before you drive it back in.  Make sure both holes line up. 

[My427stang]

Just a technique, but I always go in from the front, I just take a length out of my tool to make it shorter and put the cone on the bench

However, what I typically do to make sure I am lining both holes up is mark a line where "perfect" will be on the block, then I mark my two lines on the OD of the bearing at the center of the slots.  Then just line up the lines.  In your case, one of those lines could be an arrow too

Then drive it in from the front, they go straight easily if you are careful, and by using the lines, even if it turns a little on you, you are still within the range of the oil slots and you know the first time that you have both oil holes lined up.

BTW, it took longer for me to type this than make the 4 marks with a sharpie!

Also, I have driven them in and out before, no issues, a little bit of Green Loctite may make you sleep better as Brent said, and I agree, but don't go crazy, it does expand, so you don't need a lot

[Pentroof]

Well the cam is in, but I'm not 100% satisfied. I can't turn it by fingers only. It has a bit of "stiction" that requires the use of a stubby wrench to get it turning with a light oil film. Once moving, it seems very free.
I did end up re-installing the front bearing with no issues and a very light smear of sleeve retainer (green Loctite). I've removed the stick and felt and looked for high spots or glazing, but couldn't identify anything other than an oil slot in #4 that felt "sharp". I rolled that a bit with a chrome socket to smooth it out, but not much changed.
I'll try an old cam I have on hand tomorrow and see what that tells me. The cam that seems tight was fine in the last block and this block didn't have any issues in its previous incarnation.
I'm sure I could put this together as-is and be fine, but I won't sleep well if I don't free it up.

[jayb]

When I've had that issue sometimes I've had to shave the cam bearings to solve the problem.  Could be that one of the bearings is cocked a bit in its bore, or in extreme cases the cam bearing bores can be misaligned; I've had that issue with blocks that have been welded.

Put the cam in one journal at a time and see if you can narrow down which bearing is causing the problem.  If you have access you can go in from the front and the back of the block to try to diagnose this.

I have an old junk cam with one journal that I've cut a slot in.  One side of the slot is left sharp, and the other is radiused.  Once I've figured out which bearing is causing the problem I install the "cutter cam" in the block with the slotted journal in the offending cam bearing and carefully turn it a couple times.  It will remove a small amount of bearing material and add the clearance where you need it.

[blykins]

Yep, I have a "cutter" cam for every engine family that I do.  A cam with a slot ground in each journal. 

I have to manipulate the cam bearings on probably 50% of the engines that I do.  I never have any issues whatsoever with aftermarket blocks, but the factory stuff will suck my time away sometimes. 

[Pentroof]

Yep, I have a "cutter" cam for every engine family that I do.  A cam with a slot ground in each journal. 

I have to manipulate the cam bearings on probably 50% of the engines that I do.  I never have any issues whatsoever with aftermarket blocks, but the factory stuff will suck my time away sometimes.

Interesting stat Brent. I guess 50 years of stress and thermal cycling adds up.

Well, I have an old Cam Research flat tappet stick and an old Ford flat tappet stick sitting in boxes with their respective lifters. I'll never use either in a modern build. It seems a shame, but one of them is getting some grooves cut in each journal.

I'm thinking a 30 or 45 degree angle across the journal would also be helpful?

[blykins]

Well, some of the factory blocks didn't have straight cam tunnels to begin with.   Accurate machining processes have really taken a leap in the past few decades. 

I angle my cuts, doesn't really matter on the specific angle, I just take a Dremel with a cut off wheel and make a quick cut across the width of the surface.  Put some grease in the cuts to catch anything, put the cam in, give it a turn, and then pull it out. 

I also have a hand pump and one of my cleaning processes is to thread a barbed fitting in the front of the block and then hand pump lacquer thinner throughout the block.  You'd be surprised at what comes out, even after a thorough brushing and a jet wash.  It would probably be a good idea to do something like that in your case, so that you flush out anything that may have gotten pushed into the feed hole. 

[Pentroof]

Yeah, I think this one has taught me to change my routine. New mantra includes:

• Stick the cam in for a check before moving the block from the table to the stand.
• Install all plugs AFTER the cam check

[C6AE]

An old trick with babbitt bearings is to install a dummy shaft and hit it with a few solid blows next to each journal. The soft babbitt material will move.
This was standard procedure on engines with babbitted mains. Using a lead hammer a few blows to the counterweight adjacent to each journal and "voila" it was "fixed". This technique was standard procedure to even out machining marks from line boring the babbitt.

With cam bearings I use a dummy (old) cam and a drift punch that will fit through the lifter holes. Rotate the engine on the stand and you can "nudge" the cam next to each bearing from top and bottom.
Cam bearings have a much thicker layer of Babbitt than inserts and it will readily move around. It is often upset during the installation and I don't like removing bearing material if I don't have to.
I also use a designated mandrel instead of the "will fit" expanding mandrel that comes with the bearing driver. Those have caused more cam bearing trouble than any other thing. About 15 minutes on a lathe to make one.

[Heo]

I have made my own designated mandrel in the lathe
works good. Last time i could not find it so i borrowed
a universal kit from a friend. One bearing ended up crocked
so i made a new one and bought a new bearing and perfect
result

[66FAIRLANE]

An old trick with babbitt bearings is to install a dummy shaft and hit it with a few solid blows next to each journal. The soft babbitt material will move.
This was standard procedure on engines with babbitted mains. Using a lead hammer a few blows to the counterweight adjacent to each journal and "voila" it was "fixed". This technique was standard procedure to even out machining marks from line boring the babbitt.

With cam bearings I use a dummy (old) cam and a drift punch that will fit through the lifter holes. Rotate the engine on the stand and you can "nudge" the cam next to each bearing from top and bottom.
Cam bearings have a much thicker layer of Babbitt than inserts and it will readily move around. It is often upset during the installation and I don't like removing bearing material if I don't have to.
I also use a designated mandrel instead of the "will fit" expanding mandrel that comes with the bearing driver. Those have caused more cam bearing trouble than any other thing. About 15 minutes on a lathe to make one.

Yep, I have an old cam for this purpose too. An old engine builder taught me that one.