Is this with solid cam followers and adjustable rockers or hydraulic
followers and fixed rockers? With hydraulic there shouldn't be any need to
check clearance as the follower will take it all up safely. You only have
to have clearance with a solid lifter to prevent things expanding and
stopping the valves fully closing, which causes burnt valves and seats.
However even with hydraulic lifters you can get intermittent tapping noises,
like on mine and at least one other rebuilt engine I am aware of. On both
these you can 'play a tune' by minute changes in throttle position, too
small to cause changes in engine revs and hence possibly affecting
followers. But then on some occasions you can hear the tapping fade in and
fade out, as if the follower is rotating (as it should) and causing noise in
some positions and not others. But how can that be if the revs haven't
changed? I've changed the cam and followers, which showed virtually no wear
after at least 70k miles, with no difference. The bores didn't show any
scuffing (i.e. piston slap, and the noise only occurs when hot anyway), and
showed the honing marks over most of their surface. So what the cause of
the tapping is is a mystery. I took it to one rebuilder who said he
couldn't guarantee to get rid of the noise, so it stays intermittently
tapping. Driving at a steady speed for a hundred or so miles seems to
lessen it, then shorter journeys at lower and variable speed seem to bring
it back.
On a 4-cylinder engine valves with the adjustable rockers are usually
adjusted to the 'rule of nine', i.e. when a particular valve is fully down
you subtract its number from 9 and adjust its complement i.e. when 1 is
fully down you adjust 8, when 6 is down you adjust 3, etc. You just turn
the engine until one of the valves is fully down, then adjust its
complement. Don't set out to adjust 1 first, then 2, then 3 etc. or you
will spend ages just turning the engine to get to the right valve. However
even then it isn't always ideal, on my 4-cylinder I find that at these
points some of the valve clearances are still changing, which means the
maximum clearance can still be bigger than the book figure. So I turn the
engine one way or the other from the strict 'rule of nine' point until I
find where the clearance is at its biggest, and set the gap at that point.
For 8 cylinder engines maybe you use 'rule of seventeen', I don't know as
mine has hydraulic followers and fixed rockers. You should be able to work
it out, for any valve when it is fully down, two full turns of the crank
should put that follower on the back of the cam.
PaulH.
----- Original Message -----
> I have some intermittent valve noize, ticking sound and want to check the
> rocker arm clearance when the push rod is on the back of the cam. Is
there a
> guide that I can use to know when certain pushrods are on the back of the
cam
> to avoid taking off the valley pan? Something like with #1 at TDC, you
can
> check the valves on #1,4,7, with #2 at TDC, you can check #2,5,8, etc.?
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