fixx
 

like mentioned..you can surface grind the outside of the plate to achieve the clearance needed..

Just to be clear, my suggestion on the making up shim material for under the cam/gear interface was for mock up only. You will need to surface grind the retainer to the right thickness once you know how much to remove, and then remove the shim material.

I agree. Shim to check. Grind to use

Honest question - why is it necessary to take material off of the retainer versus simply shimming the cam gear out with some 0.005 shim stock? Are we concerned with shearing the cam gear bolts? I don't see where the shim stock itself can actually go anywhere, since it will in effect be entrapped behind the gear.

Question for some of you that have a machinist or engineering background - should a Torrington thrust bearing have end-play on it, or should it in fact have zero end-play or even preload? They are, after all, designed to take "thrust" up against their surface, hence their name. Also, from what I understand, roller cam's tend to try to spit the cam out the front of the engine versus having it walk back towards the distributor as with a flat-tappet engine, so it seems like the cam retainer is going to have the majority of the pressure on it.

You need some clearance cold to leave room for the metal to grow and not get into a interference situation. Plus it is impossible to know for sure if you have zero clearance and not actually negative clearance (interference).

The reason I would not want to shim under the gear in application is I'd be afraid of creating runout in the gear with my home made shim. Surface grinding will be quite precise.

BT, my line of thinking is that since I have determined that the problem is with the step not being deep enough on the cam, I could be in a situation where the cam gear is out of alignment with the crank gear. If the cam gear is now 0.004 closer to the engine, wouldn't that throw off the alignment for the chain? Decreasing the thickness of the retainer does not address this, but installing a 0.004 shim behind the timing gear does. I could easily check for runout with a dial indicator against the timing gear.

FWIW, at lunch I ran by the engine shop and measured another Gen VI cam. I got 0.238, just like the other one. Installed the gear and retainer and had plenty of clearance. Was able to get a 0.005 feeler gauge in between the cam and retainer.

Your chain won't even notice .004" misalignment. If you were able to purchase a stamped, hardened shim made for the snout of the cam I might consider do that. But to make one out of random shim material and expect that to hold up under the pulsation of cam lobes/harmonics and not disinigrate/fall apart is risky in my estimation.

Have you researched getting a thinner thrust bearing?

why not just have the nose of the cam cut back .003?

How do you go about doing that? They would have to cut back on the step, not the face of the cam.

I dont think a spacing shim would hurt anything between the back of the gear and the cam step face, if that shim is well built!