03 450 Valve Adjustments

[Indiana]

I'd appreciate any tips on adjusting valves you guys may have. My 450 had 2 valves just slightly tight on the intake side. So I went about re-shimming. It's just like any other project, one trip to the dealer will not get it done. e.g. the factory shim on one valve was a 182 so according to the manual I rounded did the math and installed a 175 shim but then it was too lose. The 180 shim did the trick. I was amazed that it could possibly be that sensitive. It really makes my wonder about the tolerances of the shims I bought from the dealer. My advice is to buy a couple of shims in the direction you need to shim so as to not have to return to the dealer. I was very unsure about the difficulty of the project not having done it before but it really isn't a big deal at all. I think it's very cool that I have a well used '03 and this is the first time.

[grayracer513]

You have to realize the scale of the specification you are working with. The range of tolerance for either intake or exhaust valves is .05mm from one extreme to the other. That is .0019". The 182 shim you removed was an OEM factory build shim. They have access to shims in increments of .01mm so they can set the valves exactly where they want to, no compromises. That increment is equal to .00039", so they are setting valve clearances to within a half thousandth of an inch of the target specification (which, BTW, is the low end of the spec for either valve). My guess is that the shims are likely made to a tolerance of +/- .01mm for service shims.

Assuming everything, including your measurements, was done perfectly, you first increased the clearance by .07mm, which was a mere .0027", and then decided that was too much. Since the hair of a blonde 2 year-old is thicker than that, it really is splitting hairs, ain't it?

But you're right. Anything can change the read you get when reassembling and remeasuring. Don't mix the lifters, either, BTW. That can really throw you off. It sounds like you did well.

[Indiana]

Thanks for the reply. The thing I have trouble with it is that it's such a minute measurement I'm dealing with yet it is somewhat subjective based on how I interpret the feeler guage. I do know that without question the shim I used was too lose so I'll just keep tweaking. Bottom line is that adjusting the valves really isn't that big of a deal once you get into it.

[grayracer513]

That's why I find it entertaining t see people worry so much about landing in a particular point within the adjustment range. Feeler gauges, even in experienced hands, just aren't accurate enough to split .001" with.

The job is not tough, but it can take time, especially if repetitions are necessary. There are, however, some pitfalls to avoid. The bearing locater half rings, being sure the shims are seated in the retainers, and correctly torquing the cam caps are the big ones.