Pulling what hair I have left out over these cam bearings.... Grrrrr. HELP!

[pwtjr]

Machine shop #1 did my block work, including using deck plates. All looked good when I got it back. I went to put the cam in and #1 bearing was WAY TO TIGHT, it wouldn't even go in all the way. He said maybe a bearing defect and seemed reluctant to jump into action. This left me feeling ill.

I ordered a set of Dura Bond HP cam bearings (old ones were simple Clevites) and went to another machine shop here in town. Told him the deal and he said he would fix me up.

Machine shop #2 calls me and shows me the cam in there and turned it. Cool, paid the man and shook his hand for getting me in so quick. Got home, removed cam, and see that he honed my bearings to make the clearance, which is still too tight by feel in my opinion.

Has anyone ran into this issue before? I have not. I don't like the idea of honing a bearing... maybe the shell it goes into, but not the actual bearing. Grrrrr. I need to take it back and ask him whats up and measure each one to show me the clearances.

My other option is to take it to a well known race shop in Indy. Steve Schmidt. Surely he will fix this problem the right way. Or am I worrying over nothing????

What would you do?

 

[pwtjr]

FYI
I slid each new dura bond bearing onto the respective cam journal and they fit nice before I took the stuff to machine shop #2. I guess the crush from being installed is shrinking them up but man I wouldn't think it would be that drastic. Am I thinking correctly here?
My nerves are completely shot over this deal. I just want to put my engine together man!

 

[68 HEMI GTS]

Just buy a beating knife off eBay. Scrape the tight spots, Scotch brite, reinstall cam. If tight, repeat as many times as nessessary. Some blocks are worse than others, the 400 block I used for my 511 was real tight. Took me a bit. Also, sometimes the cams are bent, stick it in a set of v blocks and dial indicate the niggle journal. You can use a big rubber mallet to straighten it.

 

[Hemirunner]

Cam bearings are babbit material overlaid on a steel shell. As long as he used proper stones and cleaned it well afterwards, it shouldn't be an issue. We prefer to use a cutter cam to open them up but honing works too. How tight does it still feel? Roll the block over upside down and fill the oil feed galleys and then turn it. Does it get better?

 

[68 HEMI GTS]

I gotta quite posting from my phone.. ( middle journal ) I would scrape the bearings a bit first, it'll probably come around.

 

[pwtjr]

Thanks for the ideas guys. I will try that and look at it a bit closer tommorow. From what I am getting so far, its not unusual to have to do this? And it isn't terrible that he honed the actual bearing? The way he made it sound, he was gonna hone the block, not the bearing. But this also made me nervous, as I thinking bearing spinnage later down the road?
Keep the info and opinions going please. Tomorrow is a new day and I will go back out to the garage with a better mindset.

 

[pwtjr]

Cam bearings are babbit material overlaid on a steel shell. As long as he used proper stones and cleaned it well afterwards, it shouldn't be an issue. We prefer to use a cutter cam to open them up but honing works too. How tight does it still feel? Roll the block over upside down and fill the oil feed galleys and then turn it. Does it get better?

It is not terribly tight and only had a thin coat of oil on the bearings, no assembly lube yet. I will give it a look and put some oil in those galleys. Thanks for the info.

 

[68 HEMI GTS]

Not unusual at all to fight with a cam on a factory big block mopar.

 

[68 HEMI GTS]

If I can't turn it by hand with the cam sprocket on its too tight for my liking.

 

[Hemirunner]

It is not terribly tight and only had a thin coat of oil on the bearings, no assembly lube yet. I will give it a look and put some oil in those galleys. Thanks for the info.

It will feel significantly tighter with assembly lube than oil. There will usually be a firm start to the turn as the cam isn't "up on the oil wedge" as it really can't form one turning by hand with no oil pressure.

 

[Hemirunner]

If I can't turn it by hand with the cam sprocket on its too tight for my liking.

Agreed and I usually like to have them easily turn by hand just using the cam install tool. The sprocket gives you just a bit more leverage.

 

[gtxno1]

The same thing happened to me the bearing next to the last one in the block was tight I dropped my block with a friend also a great machinist but not well versed in mopar he was a little squimish about doing my 915 heads the way I wanted so I took the heads elsewhere the gentleman I took them to was much older we were talking and he told me not to do the cam bearings unless they really need them because of this issue I went back and told my friend about it he said it should not be a problem well guess what it was, I left the old cam for fitment he never did it until I came to pick up my block and it was so tight could not turn easily so we had to polish the crap out of it till it fit the old man was right he had done plenty and advised against replacement unless it was needed and then it required hand fitment do it yourself and take your time you will be fine

 

[pwtjr]

Feeling better about this. Sounds like it's pretty common. It's not hard to turn, but is definitely on the tight side. I will keep playing with it until it is correct. The whole scotch brite and honing of the bearings made me cringe until I read that other people do it without issue.

 

[bm02tj]

You are best to test every bearing as you install not wait till the end

 

[miller]

I'll usually play around with the cam installed, rotating it several times. Then, pull the cam, and look all the bearings over, to see if any 'high spots' show up. The bearing scraper mentioned works like a dream on those guys.
Just play with it, until your satisfied. No one else will.

 

[62 Dart Convertible]

The same thing happened to me the bearing next to the last one in the block was tight I dropped my block with a friend also a great machinist but not well versed in mopar he was a little squimish about doing my 915 heads the way I wanted so I took the heads elsewhere the gentleman I took them to was much older we were talking and he told me not to do the cam bearings unless they really need them because of this issue I went back and told my friend about it he said it should not be a problem well guess what it was, I left the old cam for fitment he never did it until I came to pick up my block and it was so tight could not turn easily so we had to polish the crap out of it till it fit the old man was right he had done plenty and advised against replacement unless it was needed and then it required hand fitment do it yourself and take your time you will be fine

Most times I only replaced cam bearings because of the damage they cop when the block is hot tanked...

 

[mentor70]

this is very common on Mopar BBs, two issues usually seen either the cam bores are on the small side, or core shift where one or more journal is off center and this also makes cam installs tight and hard to turn.

i personal dont like removing bearing material to make the cam clearance proper. i prefer to have the journals measured and honed for proper fitment.