The New And Improved Unofficial R65 Forum V2
Technical Discussion => BMW Technical Q&A, Primarily R65 => Topic started by: Justin B. on August 28, 2012, 05:50:17 PM
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After helping Suraklyn set the valves on his Hexhead a little while back I started about the inherent inaccuracy of feeler gages, and wondered what would be wrong with using a dial indicator zeroed on the valve end of the rocker arm. Once set it seems it would be fairly easy to wiggle it up and down noting the indicator reading at the highest and lowest points.
I'm thinking a simple indicator stand could be made to screw onto the center stud for the valve cover and from there it would be a simple matter to check both sides.
This might be even more valuable on the 4 valve boxers...
Any thoughts on this possible method?
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I've only checked the valve clearances on my oilhead twice since I've had it, 44,000 miles on it now .
I've used long (12 inch) feeler gauge set from Snap-On and used one feeler gauge across both intake or exhaust valves, seems to make it easier for me at least .
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Hmm. I guess that I've always just considered it relatively straightforward with basic feeler gauges - even when doing the 16 valves on my Kawasaki Concours.
Do the Oilheads have the same things as the airheads - with the valve stem tip being slightly off center from the rocker arm to "encourage rotation", as it were??
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That's a different one, Justin! I'd heard of another method that involved revolutions of the adjuster. The idea is that for one whole turn of the adjuster the gap increases a certain amount (which I've forgotten). Having adjusted some valves earlier today, I know it doesn't take many degrees to increase the gap a thousandth or two, so maybe one revolution is .020 or .030". So, run the adjuster down till it stops, then back it out a specified number of degrees and you have it.
But I never felt comfortable with that method. The dial indicater does sound like an easy way to go.
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The rocker arms are forked, one rocker arm operates two valves .
Four valves per cylinder head .
http://www.realoem.com/bmw/showparts.do?model=0439&mospid=51768&btnr=11_2798&hg=11&fg=34
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I have no experience past airheads but I thought the deal with BMW 4 valve heads was that you had to set 2 valves at the same time using 2 feeler gauges. If you didn't have a feeler gauge in say one inlet valve you couldn't set the other one accurately because of the way the rocker bearing play was taken up.
On the accuracy of feeler gauges themselves I measured mine some time back and found a fair amount of variability. Some were spot on and some were half a thou to 1 thou out. They were always thinner and never thicker than the specified size.
There used to be a tool sold to set valve clearances based on the pitch of the adjuster thread as Wirespokes described. It was called an SPQR adjuster. I think the idea was to compensate for worn and stepped rocker pads. Never used one though. Using feeler gauges is a bit of an art when you are trying for the nearest 1/2 thou and it's always worth doing a Go No Go check with different gauges to be sure you have measured it right.