cam bearing pics

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Ironmike

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Well, decided to bump up the power this winter, on my 410 stroker. Getting my heads ported, going to a pretty big solid roller, Super Victor, blah, blah, blah.
Tearing things apart today and noticed the cam was kinda hard to spin. Too hard. So when I try to get it out, it won't come. Slide it a quarter inch out and that's it. Won't spin, won't move. Stuck.
Gently nudge it back in and just as before, it turns, but with effort.
I put on my readers and look a lot closer and see what you see in the first piture. Babbit material at the bottom of the journal. Upon looking, journals 2, 3, and 4 all looked the same.

So with a few "whacks" out she comes. The second pic is right after it came out. The last picture is the 3 pieces of babbit I pulled off the bearings.

All the bearings look good, cam journals too. Keep in mind this thing was running great prior to disassembly. Only 5400 miles. I put the cam back in for fun, and rotation effort was, in my mind, too much.

Now what? Is it a core problem? How easy SHOULD the cam spin? I'm stuck, for now. Hate to press on without knowing the outcome.

This thing had the same sorta problem when first built. My guy stood up, backed up his work and put in new bearings and a new cam....all was well. Figure I can fix this issue on my own. But how?
 

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The material most likely got shaved off the bearings when the cam was slid in on the initial installation.
 
Cam bearings are hard to install and get straight. The best way is to scrape the edge of the tight bearings but if the cam won't slide through a new bearing should be installed. My machine shop kept my old cam and cut a groove in it to be used as a reamer for tight bearings. tmm
 
Your cam bearings may be out of round and causing the cam to bind.

those shavings also could have caused some issues with the bearings.


I would have a new set installed just in case.


Once a cam bearing is pressed in and taken out, I would not recommend re-using them. They loose some of the interference fit that they need to stay in place and/or not spin/rotate.

Lining up all of the oil holes is very important. I like to get an old wire coat hanger and straighten it out and stick it through all of the oil passages and make sure that it comes through to the cam tunnel through the bearings. Check all the oil holed from the top of the main bearing bulkheads to the cam tunnel, and the oil feed passages to the head for alignment. On production street engines the factory allows up to half of the bearing hole to overlap the feed hole in the block. I would like better than that for my own engine, but at least you have a minimum target to evaluate with. Some cam bearings have two or three oil holes that have to line up.

There should be some drag when you try to turn the cam by hand without any valve train installed. It's easier to turn it with the timing chain gear as it has a bigger diameter for more leverage. The cam should not bind when you have it installed by itself, but you should feel some drag.
 
toolmanmike said:
Cam bearings are hard to install and get straight. The best way is to scrape the edge of the tight bearings but if the cam won't slide through a new bearing should be installed. My machine shop kept my old cam and cut a groove in it to be used as a reamer for tight bearings. tmm
Click to expand...


Leave it to a tool man to make a tool out of a part.... LOL! :D


And for his next trick, he's going to pull a rabbit out of a hat.... :toothy1:

(Rocky & Bullwinkle reference)
 
Ironmike said:
This thing had the same sorta problem when first built. Is it a core problem?
Click to expand...

Since it happened twice...Maybe?

I always spun mine on disassembly looking for any crazy core shift, and actually never found a problem. I did see a slight "drag" on a few fresh builds, but nothing that wouldn't "wear in" on the break in.

Those pieces of bearing found would concern me though. The thing that's hard to disseminate is how it went together twice without a red flag while installing the stick in the first place?
 
Shouldnt have to whack the cam to get it out in my opinion. Also should turn relatively easily by hand.
 
Ironmike said:
Now what? Is it a core problem? ?
Click to expand...

The cam bearing bores are machined at the factory. This should eliminate any issues with core shift.


Maybe check the diameter of the cam bearing bores before the bearings are pressed in to see if they are too small or out of round.
 
Blocks will move around over their lifetime, but I haven't found cam bores to be a major problem. What I see there is a lot of wear, and then when you had to pull it, it pulled the edge with it. Cams should turn by hand with little effort. I check mine by turning them with my fingers and the keyway or pin (big block). If I can't turn it, I shave the bearings with a razor blade until I can. It's normally the center or rear bearings for me traditionally that need it, but it's not every engine, every time. I think your guy may have just left it a little too tight. It also looks like the oil holes were not quite lined up. Lack of enough oil, and tight bearings might lead to wear like you found.
 
Good article by Muscle Motors. The thing that really gets me is the engine had 4 summers on it. I sure as hell don't baby the thing, so I'd say I run it hard. Always ran cool and with no issues at all. My shift light comes on at 6800 and it's been there regularly. No prob.

I highly doubt anyone around here has whatever is needed to properly hone the cam journals to size. It's obviously not a block I'm giving up on.

I'd like to know more about Mopers razor blade shaving to fit. It might be my only option.

Man I've changed a lot of cams over the years, but Mopars didn't come into my life until 2008. EVERYTHING seems to bit a bit odd. Never had an issue like this and it's frustrating.

Appreciate all the replies and hope to get more. I need a plan....
 
While I'm usually a proponent of the "fix the issue, not the sympton", in the case of cam bearings - it's just not worth it. If you look you can find a cam bearing tool. I use a fresh utility knife blade and you simply scrape the bearing surface on the tight bores until the cam fits. The cam bearings get as much oil as the main bearings so it's not like the bearing surface has to be perfect.
 
I agree with 'ya 100 percent. I don't mind making the bearings fit. And after fartin around with it today, I'm sure it's the middle and the rear that are tight.

Man I'm telling you, that Scat bottom end looks beautiful. Mains, rods, everything. As much as I pound that thing I was expecting to see signs of main walk. If I wasn't so paranoid, I'd re use the mains and rods...

I will have the cam bearings replaced and "scrape 'em" if I have to. I did a search for cam bearing tool, and all I'm getting is Harley stuff. Anyone know where I can get the right tool?
 
Ironmike said:
I will have the cam bearings replaced and "scrape 'em" if I have to. I did a search for cam bearing tool, and all I'm getting is Harley stuff. Anyone know where I can get the right tool?
Click to expand...


Try toolmanmike, he sells tools and may have one or tell you where to get one.
 
Have you checked the cam itself is still straight?

I've also used a used slotted cam as a reamer to ream the bearings. But that's only when new bearings were installed.
 
BigBlockMopar said:
Have you checked the cam itself is still straight?

I've also used a used slotted cam as a reamer to ream the bearings. But that's only when new bearings were installed.
Click to expand...

Also a good idea. They have been known to get bent in shipping. One drop of the box and they can bend.
 
Roll the cam on a flat surface, see if it wobbles. You can make a cam bearing installer with a few freeze plugs and some all-thread. Put bearing on rubber puck, tighten so its snug and then use coupler off threads and allthread to make the driver. tap in from front. You can pull them in too, just use allthread as a jackscrew and a few large washers. line up oilers. Uut rear one in and install cam, turn to suit, then next one, find bugger and scrape, repeat.
 
A Bearing Scraper is what you're looking for, there are lots of them on Ebay
 
Got this issue resolved. Local machine shop guy already knew about the LA problem. Has a fixture to correct the journals and make it all perfect. I'm sorta glad I didn't have to scrape any bearings. Will be running fairly high spring pressures and feel alot better with fresh, un-modified bearings.

Thanks for all the help, guys!
 
Last engine that I built that is in my scamp.... along with line honing the mains I also had the cam journals line honed as well. That engine is a free wheeler now. It spins the easiest out of any engine I have built to date. 2 fingers and the cam spins like it is on butter. In the car it revs real quick too. From now on I will always have this done.
 
I will also be darn sure to have it done, if I build another one... Hey MadDart, I saw you're running a solid roller. What rockers are you using?
 
Never woulda thought of PRW. I have a set of Hughes 1.6, but really don't know how long they'll live unfer high spring pressure.
 
Ironmike said:
Never woulda thought of PRW. I have a set of Hughes 1.6, but really don't know how long they'll live unfer high spring pressure.
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Yeah when I built that engine Hughes was switching tooling companies and they were out of them for a really long time. This is the only reason I went with PRW. The PRW's seem to be up to the task for sure.

My spring pressure over the nose is only 510 lbs.
 
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