Umm, I don't see the practical difference, but maybe I don't understand
what people are calling the "rule of 9". But I wouldn't be too sure that
the intake and exhaust lobes are totally symmetrical, so that you only
need *exactly* 4 positions... I would look at each one independently,
regardless. Remember, even when the valve is completely closed, the cam
lobe may not be at its point of greatest clearance yet, depending on the
existing gap, and the intake and exhaust are at different points in the
cycle (one just closed and the other is just about to open). Certainly
the pairs of valves are very close to being closed perfectly
simultaneously, but you really need to find the "midpoint" of closure for
each, if that makes sense, not just any point.
Larry Colen had this to say:
>I hope that I'm not repeating an old tired thread, but I've got a
>question for the wisdom of the list:
>
>In addition to "the rule of 9" I've also seen valves adjusted
>by turning the crank until both valves of one cylinder are rocking
>(TDC between blow and suck) and adjusting the valves on the
>complementary cylinder (TDC between squeeze and bang), at which point
>both valves should be completely closed.
>
>This method has the advantage of only needing to find 4 crank positions
>rather than 8. In theory, this seems like it should work just fine.
>
>Comments?
>
> lrc
>On Wed, Aug 30, 2000 at 10:54:29AM -0700, Jon wrote:
>>
>> <SNIP>
>> > the exhaust. I have recently discovered on some
>> > valves that if I set the
>> > clearance on the exact 'rule of nine' point there
>> > can be an even bigger
>> > clearance a little way before or after that point.
>> <SNIP>
>>
>> I've noticed the same on my "B". I guess it's not a
>> stock cam. Is it best then to adjust the valves to
>> .015 at the point where clearance is largest?
>>
>> jon
>>
>> =====
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>>
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>
>--
>Million Monkey Software -
>Our code sucks, but you should see this thing we wrote called Hamlet.
>lrc@red4est.com www.red4est.com/lrc
>
>
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
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