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Valve adjustment: how close is close 'nuf


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When I spent some real 'quality time' getting the valve gaps JUST RIGHT on my oilhead or hexhead, the reward would be a glass-smooth, quiet engine.


Now that my current steed has shims ('semi-spheres?'), I wonder if I need to be as anal about getting the gaps 'dead bang' right, seeing that to do so, I would have to have acquire a collection of those little buggers.


Here's the stats at 30K:

intake gaps: .13, .13, .14, .16 (acceptable: .13-.23)

exhaust gaps: .35, .38, .38, .40 (acceptable: .30-.40)


I understand that it's better to have a larger gap for better valve cooling--so it looks like an adjustment is soon needed on the intakes. I hear that camheads require far less valve maintenance than the older models, so maybe once the changes are done, it would last a very long time.


So, my question: is it worth my time / investment to reduce the variance in gaps (by replacing shims), and would it result in a smoother performing engine?? I don't mind spending ~ $7 a pop, since my nearest dealer is about 4 hours away.


Anyone out there have swapped shims and noticed a smoother engine as a result?

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Morning Ken


You won't notice any smoother operation by evening out the valve settings (just not that critical).


I personally like to run the exhaust near max but the intakes I keep in the mid range (but again, as long as within the BMW spec range, you won't have any issues)


As far as acquiring a collection of semi-spheres?--in a lot of cases you can swap your existing semi-spheres between positions & gain on a couple of valves so your next move is to see what you have at what position (you already have the lash per position) then figure out if you can use a few of your existing at different positions. Then you can buy what you need to finish out the remaining valve positions.





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