I finally found a block for building a 496 for the 66 smile.gif That's the good part. I'm a little concerned about this: http://www.chevelles.com/showroom/lance-w/496Cam.JPG
I was told that the surface was cut back to allow the use of a Torrington bearing behind the cam gear. Is this common? I've never seen it before. A little history on this block... It's been sitting in the corner of a garage for about 20 years. It was put there after having been to the machine shop where it was bored (but not honed) +.060 (actually measures .050) and decked .006 and the mains appear to have been line honed. All in all it's a great block for what I want to use it for (a 496).

Lance

Looks like the opposite of having a timing gear machined for the thrust bearing like mine:

http://www.72chevelle.com/images/engpics/pic176.jpg

If you find the right bearing, you could probably use a standard timing gear.

That kinda looks like the p/n#200-96-acw anti-cam walk kit Isky sells, it comes with a special cam bearing with a step on the nose and a thrust washer. I would check if that is a standard cam bearing or if it has the step on the end then figure out what you need. Hope this helps.

Hotrod66,
Yes, I found the Isky kit yesterday when I did a web search. The cam bearing that's in there is just a "normal" one but obviously you could remove it and put the isky one in. One of the problems I have is I don't know how much the machinest removed or how much the Isky kit requires you to remove. I need to find another big block and measure the stock boss to see how thick it started out. I'm not going to be running a roller cam (cost) in this motor so I'm also looking for ways to restore the boss to allow me to do without the Torrington bearing. I'm thinking a custom cam bearing made from a peice of oilite bronze. Ahh the life of a modifier smile.gif

Lance

Lance,
I have used the Isky Torrington bearing kit on several big block Chevrolets, with excellent results. Cannot remember how much we mill off of the block to use this kit, but Isky can tell you. Their phone number is 323.770.0930. The Isky kit is designed to eliminate roller cam 'walk', but it wouldn't hurt anything to use this setup with a flat tappet either, as far as I know.

Lance,

If I recall correctly you can lay a straightedge across the timing cover gasket surfaces, measure the gap from there. Get an idea, anyway.

Tom

Hi, I found this old thread searching for the ISKY cam thrust repair kit,
I have a similar issue, I think.
http://i307.photobucket.com/albums/nn315/bigcrunch69/101_0369.jpg

provide me your feedback if the isky kit will fix it...

ive had a torrington bearing and stepped cam bearing on my 454 for 20 years. the block is machined and a small step is machined on the front of the cam bearing to accept the slightly smaller i.d. of the thrust bearing. in other words the thrust bearing is centered on the cam bearing which now sticks out of the block about .125. the only thing about this set up is that if the cam comes forward enough the top thrust washer can drop down so you need to use a button. another option would be to purchase a thrust washer shim kit from cloyes . these washers are about .020 if i remember right and ride on the cam journal instead of the bearing like the isky kit. you would just have to use the right number of shims to get the cam alignment right and machine a little off the front of the bearing or not install it as deep. make sure the oil hole lines up

Gary, your block is machined like mine?

here is what I found on the Cloyes shims

http://www.cloyes.com/HighPerformance/Products/Accessories/tabid/185/language/en-US/Default.aspx

From what I have been informed so far is the face of the block or the cam gear gets machined to compensate for which ever shim or torrington bearing one uses.

The pocket in my block is only 2.6" + dia depth I think is .150 but I will need to remeasure that dimension.
http://i307.photobucket.com/albums/nn315/bigcrunch69/101_0369.jpg

When I bought the block it came with these two shims
http://i307.photobucket.com/albums/nn315/bigcrunch69/101_0370.jpg
http://i307.photobucket.com/albums/nn315/bigcrunch69/101_0371.jpg
http://i307.photobucket.com/albums/nn315/bigcrunch69/101_0372.jpg

The first steel shim does not come flush with the surface of the block so thats not right.
The bronze shim has wear on it so it needs to be replaced.

I have even considered welding the machind recess back up, rebore the cam hole then surface it???

i was under the impression that the block was allready machined. to me, milling the block and going with the torrington thrust bearing is the way to go if the cam thrust face is worn.if you can use the shims and they fit in the wear groove and you can get the alignment right then that would be ok too.

I think another option is to use a Gen VI cam and retainer plate setup. The cam has a shoulder on the front and the plate retains the cam and keeps it from moving back and forth thus no need for a cam "button" or Torrington bearing.

I have not tried this yet but will build a new 489/496 using a Gen IV block but use the Gen VI cam retainer setup.