Date: Wed, 4 Dec 91 13:20:28 CST
From: Zahid Ahsanullah <zahid@serval.sps.mot.com>
Whats' the reason that valves in older cars make that tic-tacking
noise even if you adjust them to specification.
One likely possibility is that they aren't, in fact, adjusted to
specification. This often happens because the rocker arms get dented
in where they contact the valves. When this happens, it becomes
impossible to adjust the valves correctly with a feeler gauge - the
dent causes extra clearance and thus ticking.
If this has happened, the best cure is of course to replace the rocker
arms. If you can't do that, I imagine you could adjust the valves with
a dial gauge instead, which would take the dent into account - but
this will be difficult to do accurately if the rocker's bushings or
the rocker shaft are at all worn. Some people try to regrind their old
rocker arms. You can do this, but you have to get the shape right (so
that force is applied straight down on the valve, not sideways) or the
valve guides will wear faster, and (many? most? all??) rocker arms are
case hardened, so if you don't re-harden them after you grind, they
won't last long before getting pocketed again. Nonetheless, it can
work acceptably; I've got 40K mikes on a set of reground TR3 arms, and
they're still in good shape.
-john
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