Knocking in a cam bearing, and it's tight

[Paul_G]

I nicked a cam bearing while cleaning the block. So I got a set of Clevite bearings, took out the #2 bearing, Looked it over and knocked it in. Just changed the #2 bearing. Now the cam wont go all the way in. It stops about 1/8" going in to the bearing. very stiff trying to rotate it. Wont turn by hand. I knocked it all the way through. On the bench I test fitted it on the cam and the same thing, it is very tight getting it on that journal. It has no oil clearence at all. Should I use some 3000 grit and open it up? Send it back? What do you do when this happens?

 

[threewood]

There is a specialty tool used to ream a cam bearing. I have also heard of people using an old camshaft with a cut in the bearing journals to ream in new bearings.

 

[Kern Dog]

You didn't specify what type of engine that you're working with.
My machinist told me years ago that big block Mopars were notorious for poor fitting camshafts. He said that the cam bearing bores were not all perfectly centered. The trick was to install all the bearings then line bore the bearings.
Yeah, it sounds strange to me too.
The 440/495 in the red car and 383 in Jigsaw both had tight fitting camshafts that required clearancing with this:

Yeah, diagonal grooves were cut into the journals of an old cam. This was covered in chassis grease, inserted in the block and spun several times. I'd pull it out, try the new cam for fitment and if it still didn't spin freely, I'd put the cutting cam back in and spin it some more.
Good luck.

 

[pnora]

You will have to scrape the bearing down to get it to fit. There are bearing scrapers you can buy. Scraper

 

[Paul_G]

You didn't specify what type of engine that you're working with.

I am refreshing my 505 stroker right now. Had no plans to replace the cam bearings, or any of the bearings. They all were great. It went lean and detonated badly. I am putting a lower compression piston in with new rings and going through the heads.

I measured the inside of this bearing and the cam journal. They are just a few ten thousandths apart. a different journal has .006 oil clearance.

 

[69Bee]

Bearing bores have gouges, raised metal around the drilled holes, etc. I usually ALWAYS have to scrape the bearings to get the cam to fit. One trick I do is to use a ball hone on the bores before the final wash to knock down as much as I can and sand/file any bad spots. The bearing will show the high spots so scrape, test fit, rinse & repeat until it fits. And, under NO circumstances use any sand paper on the bearing.

 

[dvw]

Scraping works find the shiny spots an do a little and fit. It's a slow process. Using an old cam with slits cut in each bearing journal at a forward angle works slick. Press and rotate. It''ll trim off high spots on any one of the five journals in one swipe.
Doug

 

[Geoff 2]

Is it the brg.....or the cam journal that is tight??? If it is the cam, I would be removing metal from the cam, not the soft brg material.