> > 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...>
> |
Well, you're one up on me. I no longer have a 1500 manual, haven't seen
one in *years*. I remembered (apparently misremembered) them giving the
TDC four at a time method.
>
> 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.
>
It's still the same pattern, add up to 9 or 13. You're just moving the
crank 20 degrees to either side of 90 (where it wants to stop) to get
the individual valve full open.
> > 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.
If, in ten degrees of cam rotation on the center of the heel, you find
a measurement difference, the the base circle is not round. I would not
be surprised at this. But then, where is the best place to set the valve
lash?
> 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.
>
Setting them loose will just wear out the cam and lifter quicker. You
will not drop the flow much, if any. And, assuming the fouling is fuel,
it's not the flow rates causing the problem, it's the mixture distribution.
Does the car bog a bit when you stomp on it after a bit of idling, such
as traffic lights? Does the car stutter/stumble after a hard right hand
turn? If so, you may be suffering from what I call the Weber induced
Lake Erie effect. During times of high vacuum (idle, overrun), the temp
in the manifold drops drasticly. This causes the fuel to fall out of the
air stream,, and puddle at the lowest point. With the 1500 (and TR6)
DGV manifolds, this is under the carb. Then, when you hang a quick
right, this lake gets sloshed up into the #2 and #3 runners, flooding
these two cylinders.
The only thing that can be done for this is to make sure the water
heating on the bottom of the manifold is hooked up, and working full
time. All too often, these pipes are not connected, or are tapped into
the heater circuit.
> timd@ptltd.com (Tim Dziechowski - Phoenix Technologies - Norwood, Mass)
>
Randy
randy@taylor.wyvern.com
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