John,
This is on a 2000, correct? Mark had a good comment about
the 1600 rocker arm & rocker shaft, but my comments are
with a 2000 in mind.
I suspect the backside of the rocker arm might be making contact
with the top of the valve spring retainer. By adjusting the valve
clearance tighter, you might actually be leaving the bottom of
the rocker in contact with the top of the valve spring retainer.
Not good.
Ideally the rocker arm should be "level" with respect to the valves
and pivot point.
On the old Bronze valve seats, I have seen them pound into the
head over the years. As it does this, it raises the top of the valve,
so you need to keep lowering the valve adjustment pivot. As
this occurs, the pivot is lowered to compensate for the valve
height. This will leave the rockers away from the idea "level"
position, but at a "uphill slope" with regards to the rocker arm.
Clearance between the bottom of the rocker arm and top of
the valve retainer is reduced.
Also when the valve seats are cut, during a valve job, this will also
raise the top of the valve. Once again the pivot is lowered, but the
rocker arm is now at a little of an "uphill" slope.
Has the head been shaved? Typically you want both top and
bottom of the head machined if it has, with milling the top you
need to install cam tower shims to both adjust the cam height
(for the timing chain) and to also raise the cam above the
rocker pivots and top of the valve stem pads.
Try putting some thick paper between the rocker and top of
the valve spring. Turn the engine over by hand to get a full
rotation of the camshaft (I just leave it in gear and push the
car back and forth). If there is not enough clearance, it will
cut the paper when contact was made.
Quickest solution is to "grind and polish" the bottom of the
rocker arm were it makes contact.
Might be other issues, but I would check out the clearance
issue first. I have seen different rocker arms over the years,
some of which seem to have a thicker casting causing the
contact issue.
Cheers,
Tom Walter '68 2000 - Rodney
Austin, TX
jschmi7@us.ibm.com wrote:
> I have had this problem ever since a rebuild several years ago. If I
> adjust my valves to proper settings when hot, ie. .008 - in and .012 - ex
> I get excessive noise from one of my valves. I resorted to using a hose as
> a stethescope and ran the engin without the valve cover until I pinpointed
> the noise to, I thought #3 exhause. So I adjusted it tighter until the
> noise subsided to a reasonable amount.
>
> Yesterday I decided it was time to do a complete tuse and readjusted my
> valves to all proper settings. Again the noise is back. Rather than just
> adjust the valves to an unacceptably tight setting, I thought I would ask
> the group if anyone else has had this malady. And, does anyone have any
> suggestions as to what may be causing the problem.
>
> I would really rather not pull the head, at least until the snow flys, but
> would like to have the use of the car until then, if possible. I have a
> feeling that it is a miss cut valve(some were replaced at rebuild) or
> rocker pad worn or sometning like that.
>
> Thanks in advance for the help.
>
> John Schmitt Telecommuter Office # - 847-458-7829
> Internal phonemail only - 847-240-4725 pager pin# 800-759-8888
> pin 8710561
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