Cam journal size question

Oldhemidude · Post by **Oldhemidude** » Wed Feb 16, 2005 7:03 pm

When opening up a block for roller cam bearings is it better to use all the same od/id size bearings on all 5 journals?

I was thinking that same size journals would be much easier on the cam manufacturer ( my pocket also) and that using 1 inch wide bearings on the mid 3 and .625 on the outter bearings would make life good....

Does this seem the best and most reliable method?

These are going into KB aluminum blocks and I am planning on using Torrington, or the heaviest duty bearing, cycle wise, manufactured.

Thanks or the help.

ChrisU · Post by **ChrisU** » Wed Feb 16, 2005 9:36 pm

If you use all the same dia. bearings you're allowing the machinist to hone through the entire bore instead of having to worry about holding one bore, within a radial tolerance to the other.... just a much cleaner deal, one bore, one hone straight through.

CNC BLOCKS · Post by **CNC BLOCKS** » Mon May 30, 2005 9:04 pm

On the blocks that we machine for roller cam bearings we machine them all to the same size and on the aluminum blocks we run .0025 to .003 interfearance on the bearings.

This is a picture of a Dart aluninum block .391 raised cam tunnel that we machined 2.282 for the Durabond cam bearing P/N GMP-55-T which is a babbit bearing and you can run a 55MM cam core and we are also machining the lifter bores to .904

But if running a SBC with Roller cam bearings for the 50MM cam we run the wide bearings 2-3-4-5 and the narrow bearing in the front to clear the fuel pump push rod and if using .904 lifters a narrow bearing must be run in number 3 cam journal to clear the 2 lifters on each side.

And we have found by going to the BHJ Cam tunnel fixture we have found that the cam tunnels arn't truely where they are suppose to be.