[fsted]

i am working on a 455 i recently acquired,tore it down to the shortblock to see what i had. everything looked good just going to change the cam and reassemble. ordered a new crower wont even go in the block! stops at the second bearing. so i did some searching on this board found a bunch of threads. so far i pulled the front 2 bearing and replaced them because the #2 looked crooked. no better so i cut some grooves in the old cam to true the bearings.the new cam goes in now but is still hard to turn. so what do i do now? keep working the tool? i read in some old posts the cam bore is to tight and the root of the problem. can the bores be honed with 3 stone or a ball hone with a drill motor? polish the cam it measures 1.900 the old one is .001 smaller. what really sucks is i now have to disassemble a perfectly good shortblock to clean it. need some advice from those that have been there done that.

[GTO2nv]

I have experienced a twisted block,the camshaft would not turn. It took a hammer to install it and a pry bar to get it out. I had to have the machine shop line bore the cam journals to fix the problem.

[455firebird1969]

I had the same problem. I used a cam bearing rem/inst tool, to remove and reinstall the bearings, hoping one was cocked a little, but the cam was still too tight. Eventually I cut a groove in an old cam and worked the bearings until the cam would rotate. I was worried about it at the time, but five years and over 850 passes later, I dont worry about it anymore. My engine made the fastest pass ever last fall, towards the end of the season. Its still going strong even though I had to hog-out the cam bearings...

Take the tool to it again...

Next time I'll check it before I bring the block home from the machine shop, as long as I dont forget again...

[screamingchief]

There was another fella here not too long ago that was having problems with his Crower #60243 cam being a little too tight,and his conclusion was the journals were just a bit too big,but they still fell within the accepted OE specs for journal size,but it seems that fate conspired to "stack" all the clearances opposite each other so it was a "no-go" situation.

(ie: high end of spec cam journal OD with low end of spec cam bearing ID.)

His previous cam with slightly smaller OD journals fit with no problems as I recall.

I believe he wound up getting a different brand cam because Crower was'nt really being all that helpful with his problem.

Not sure if that helps much here,but it's something to keep in mind maybe.



Bret P.

[Matt Meaney]

would you be able to post a pic of the tool/cut you made in the old cam? i need to do the same thing and am not sure on how to cut the old cam. thanks.

and anyone, just how easy is a cam susposed to turn? probably doesn't have a value like a pinion gear.

[BruceWilkie]

Should be able to turn with your fingers twisting on the cam bolt and not feel any axial play. A slight drag is acceptable if you can still turn with your fingers.

[screamingchief]

Originally Posted by Matt Meaney

would you be able to post a pic of the tool/cut you made in the old cam? i need to do the same thing and am not sure on how to cut the old cam. thanks.

The pics have been posted a couple of times here on the forums already,a search should bring them up pretty quickly.

Use "cam bearing" or such as the keyword and the thread should pop right up.

I saved a couple of those pics,but I've been moving a lotta pics around in various folders on my file server drive so they could be just about anywhere right now.

And I'm too lazy tonight to dig up a link to one of those threads too.

Sorry.

Bret P.

[BLACK70GTO]

Recently had the same problem, comp cam was .0002 to big you had to force it in . Measure another new cam for base line & tried it and fit fine. Put cam in a lathe and polished it .0002 isn't that much !! fits fine no problems,

[6t7gto]

Check this...
http://forums.maxperformanceinc.com/...ht=cam+bearing

[Cliff R]

I've ran into this a lot over the years, but much less since we made our own custom cam bearing driver specifically for Pontiac engines.

Tight fitting cams are pretty common on 455 blocks, and a problem with just about every 428 I've ever assembled, especially the 1969 blocks.

In any case, first you have to make sure the cam isn't the problem, and mics within spec and is straight, most will be.

The bearings need to be releived so the cam fits and can be turned easily by hand with no tight spots.

I just use fine auto body sandpaper to the bearings once determining where the "tight" spots are at.

I also chuck the cam up in our lathe and polish a few ten thousanths off of it if/as needed.

The end result should be a nice fit without any binding anyplace, and with the gear on the end you should be able to spin the cam with very little effort......Cliff

[mgarblik]

As stated, tight cams in big journal Pontiac engines are pretty common. I have seen the problem in 421, 428 and 455's. I would start by making sure all the cam bores and super clean and no nicks or rolled up spots on the bores from someone beating the bores up removing the old bearings. Then if the block is empty, I scotchbrite the bores with gray ultra fine to make sure they are really clean. Then on a problem block, I install the front and rear cam bearings first and test fit the cam. If the cam turns freely, with those two bearings installed, it is likely if there is a problem after that, the line bore is banana shaped, which I have seen numerous times. I would then install the number 2 or 4 bearing and test fit again and so-forth until you isolate a tight one and then once isolated, deal with it. My experience has been #2 and #4 are the problem bores. Yes it is best to have it line bored or line honed, but usually a light touch-up with a line hone will fix them and you can use stock bearings. Once you line bore them, finding a set of bearings with the correct OD and ID can be a real pain. Some I have had to modify and make my own oil holes. Time consuming and expensive for a customer. Because of the problems with Pontiac, Oldsmobiles, and Ford FE blocks, the camshaft bearings and the camshaft are the first parts I install when building one because of the shavings that end up in the engine fitting the cams. As a side note, at least on Pontiacs, my experience is Federal Mogul punched one piece bearings have the loosest fit on the cam. I like Durabond bearings, but they always seem to run tighter. Clevite/Michigan cam bearings, especially the flat ones with the puzzle piece joint are very inconsistant, tend to peel at the joint and I don't use them anymore. Based on your original post, I would try to fit the old cam in the block now with the bearings you have in there. If it turns nicely, the cam journals are a little too large and could be down sized easily. Even the best cam makers make a mistake every now and then. You absolutely do not want to run it tight. A spun cam bearing or worse will be the result. Good luck.

[fsted]

well i have been working on this simple cam swap all day now. i pulled the piston rods and crank, so i could work on the bearing easier and clean the block. the rear cam bearing was installed to far to the rear almost covering the oil hole! new bearing and the magic cam tool and all is well, new cam turns easily now. i had to add another groove to the tool as the first one would fill up and no cut anymore. i am now concerned about the rear seal, i was not intending to go this far into the engine and did not order a new seal. i have one that came with the fel-pro gasket kit but i have heard they are not very good. i am thinking of reusing the old one, because the engine was not leaking and the seal looks like one the older ropes. i was very careful taking it out, think it will leak if i reuse it? i guess its a good thing i had to go through all this because this engine was filthy caked with old dried up oil stuck in nooks and cranny and oil passages. it took hours to get this thing clean i pulled the oil galley plugs and cleaned it all as best as i could. also tapped the front holes while i was there. here are some pics of the cam tool. opinions on the rear seal? i really want to finish this project this weekend ,not wait on more parts. ED

[440GP69]

Your rope seal may or may not re seal, ive never had really good luck with those, i use BOP's in all my builds
Your cam tool looks good just cut all 5 journals on your tool then put it in to Swipe the babbit, make sure your cam tool is a good straight core!, And you can just cut straight lines in your tool but deburr it before use
Last if your new cam has larger journals than your cam tool well your pissin in the wind LOL, Then you'd have to do what Cliff R said, G-luck

[Matt Meaney]

6t7gto & fsted,
thanks for the link and pics, clears things right up.

BruceWilkie,
yep, mine's definately too tight.

screamingchief,
no need to apologize, was kinda lazy myself, not to do the search thing. ;^)