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| Joined: | 05-01-2005 |
| Location: | Minneapolis, Minnesota USA |
| Posts: | 575 |
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When the valves are ground & lapped, a small amount of material is removed from the mating face. As a result, they end up moving a little deeper into the valve seat. The whole valve moves up in the head, pushing the shim and tappet up with it and closing the clearance between the tappet and cam.
If the shop had done a thorough valve job, it would have measured the height of the end of the valve stems after being ground, then ground an appropriate amount off the ends of the stems to maintain the correct stem height. From what you describe, it doesn't sound like they did that step.
The cam carrier gasket is about .010" thick. Removing it lowers the cam carrier relative to the valve stems and the clearances get tighter. On a factory original engine, the valve shims are usually fat enough that removing the gasket is no problem. But for you, it sounds like the easiest solution would be to continue using the gasket and then have a few shims custom ground a little thinner. A few thousandths thinner is no big deal, but don't make any really thin shims. Like less than .050"
Any general machine shop with a surface grinder can custom grind the shims for you. Just figure out what you need, bracket the list at least one size either way (+/-), then have the whole batch of shims done at once. One set-up charge at the machine shop will cost less than going back repeatedly everytime you decide a different shim thickness is required.
Ideally, the valve stems should be shortened so shims mid-range in thickness can be used, and the gasket removed. Also counterbore the oil passages at the front of the cam carriers to take the small O-ring that you're supposed to use when the gasket is deleted.
Good luck,
Tim