>> The difference in lash by either method is very small...at most half a thou.
>> The workshop manual method is more accurate.
> The method I describe *is* the workshop manual method for the engine in
> question (BMC A series). Some companies suggested a method of setting the
> engine directly on TDC and adjusting four at once. This suggestion strikes
> me as not very sound. Doing it this way, none of the valves will be directly
> one the back of the heel, and two of them will be real close to the leading
> or trailing ramp. A little bit of wear in the cam, and you'll be out of
> the ball park.
Both the Bentley factory workshop manual for the 1500 and the Haynes
Midget manual give the same chart for adjusting lash:
With valve 8 fully open, adjust valve 1
<the manuals are home in the garage,
and I unfortunately am not...>
Setting lash for each valve individually using this chart ensures
that the valve is on the heel of the cam. I've seen the two-at-a-time
and four-at-a-time methods in other manuals but got inconsistent results
when I tried them.
> What evidence do you have that this later method is more accurate?
Direct measurement. I set lash using two-at-a-time, with the engine
rotated to average out the slight difference in lift between the two
open valves. If I then rotate the engine so that each of the open
valves is at maximum lift and check the lash of its opposing partner,
my feeler gauge is a very loose fit. I was worried about possible
cam wear, but it seems like the heel should wear last and least, and
this cam is fairly fresh.
I'm taking all this trouble with lash because cylinders 2 and 3 keep
fouling plugs and I want to make sure the intakes on those cylinders
are fully seated. This may be and probably is a flow problem with my
(Pierce, Weber DGV) intake manifold. If so I can tweak it slightly
by setting the intakes on 2 and 3 a thou loose to reduce their flow.
firstname.lastname@example.org (Tim Dziechowski - Phoenix Technologies - Norwood, Mass)