Majic Jack

Installed the camshaft in the 455, everything progressed satisfactory until the rear cam bearing. Had to tap it into place. Cam will not rotate by hand. Pry bar does move it. Suggestions were received to hone the rear cam bearing? Anyone else encountered this situation and if so, the solution.

wr1970

I would pull the cam back out a look at the rear bearing to find out why it fit that tight first.

Milan..

The cam installation tools I know of install the cam bearing rear to front , with a large tapered tool in the front cam housing bore to keep everything straight....? Do you have one??

droldsmorland

^^^^what wr said. Somethings not lined up or out of spec. Did you install new bearings? Its worth replacing the bearings. They're cheep. It should spin by hand, somewhat snug but not tight. If its in the car its certainly not as easy to R&R cam bearings. But your alternative is wiping out the cam.
Pull the cam and look at what the witness marks are telling you on that bearing and report back. Honing should only be performed with the right tool and expertise.

Milan..

You can not hone babbit cam bearings.....

11971four4two

do not hone the cam bearings

a bearing "knife"
can be used sparingly


good luck

jensenracing77

I had the same thing on our 62 Jetfire. My situation was likely a little differant because they don't make the correct cam bearings for the 62. We ended up honing the bearings and also turning down the cam journals. DO NOT turn the cam journals on the 455. It would make a cam swap later a nightmare. I would think honing the tight bearing would be ok but I am wondering what went wrong in the first place to make this happen and what else may have issues. Is the cam bent? Was the bearings installed correct? Is the line bore for the cam OK? I am not an expert engine builder but I would want many more answers to questions for why it is doing this. I just don't have much faith in very many machine shops.

wr1970

All i am saying is find the root cause why it fits so tight.Then it will be time to decide what to do next.

Milan..

And be sure the cam is straight , do not re-use the cam bearings.....

coppercutlass

I had a cam with about 3 thou run out . so thats 1.5 splitting it but when i spun the cam you literally hear it howling. Get new cam bearings either pay a shop to do it right or buy the tools to do it right . A cam should spin freely with only one finger when installed dry with no oil which is only done to make sure the fit is correct. I didnt know any better and ran the engine one whole summer like that ( learned alot from that experience ). Caught i just in time before i spun the cam bearings. It explained the chirping sound i was hearing. All the bearing material had clogged the oil passages so the cam was not getting much oil. On high rpms it sounded like a dry water pump.

wr1970

^^^^^^^^^This

steverw

I had the same problem, took it back to the machine shop they put in a new bearing no charge. Then the cam turned as it should. The bearing is probably cocked a little. Just replace it while its apart, you will be glad you did.

11971four4two

you had to "pound" your cam into the
bearings

you are on the wong track

Run to Rund

Make sure the problem is the rear bearing. The bearings get sequentially smaller from front to back, so any of them could be the tight one; they don't "engage" until the correct journal is on the bearing. That is, when #2 cam journal is on #1 bearing, etc. they are all loose and you can't tell if they are within size specifications.

bccan

How about popping the rear cam plug? Easy to see rear bearing, easy to measure and easy to "tap" the cam forward.

joe_padavano

^^^THIS!

It could be improperly installed bearings, or a burr on one of the cam journals. Check everything. And hammering on a cam is NEVER a good thing. As soon as you picked up the hammer, you KNEW there was a problem and should have stopped.

Majic Jack

I have owned and used a professional cam bearing installation tool for over thirty years and yes the bearings are new. I am acquainted with the sequence of one to five and was careful to check alignment and oil hole location. The witness marks appear on both left and right sides of number five rear cam bearing. Tried a different new cam which did not fit at the rear either. The block was commercially cleaned twice and the crank journals were line bored. However the left rear oil galley remained plugged at number five and seven cylinder areas. Drilled and brushed out the blockage. Possible distortion from heat at the rear cam bearing port area?

Milan..

1. Take the cam bearings out
2. Fit the cam after installing each cam bearing , starting with one and two until it sticks.
3. Does the block have any sleeves?
4. A properly shaked and baked in metal shot , block should not have any blocked oil galleys..

Destructor

In engineering terms it's called "Bang to fit".

joe_padavano

Actually, in the aerospace world, the saying is "pound to fit, paint to match".

coppercutlass

In a body shop bang to fit is a way of life.

Majic Jack

No sleeves, bored thirty using a portable boring bar by probably the best retired machinist in town. I have two 1970 blocks underway, a 350 and the 455. I slipped both cams into the 350 and both fit without persuasion however neither will turn freely with only one finger. Leads me to surmise the Dura-Bond brand bearings may not be exact. Have an NOS set of TRW as extras. Perhaps I should try these as old mechanics in the neighborhood advise, assume nothing with the new parts of today.

oldcutlass

And if it don't fit get a bigger hammer. I would try the TRW's.

Majic Jack

Removed number five cam bearing and it slips over the end of the cam just fine. These bearings crush upon installation and apparently spring back into shape upon removal. The problem lies within the bore of the rear journal. Less than 2.088 as required. Went down to a local machine shop that has survived for a hundred years or so and inquired. They loaned me a ball hone with the following response, the former partner was an expert at curing this problem, however unfortunate, he is boring blocks in the hereafter, Pontiac, Chevy practically never a problem, big block mopar and aluminum Cadillac,are notorious. Olds 350 rarely if ever, however the 455 normally not but can happen. They have discovered, over the years, that Olds, rather than correct the bore would just install an alternative bearing. Anyone else have any reflections on this matter.