DeTomaso Mailing List: November 99, Message #228

I have what I describe as a valve lash "clack", but have not been able to
track down the source.  The engine was completely re-built by a local
performance shop.  The sound slowly appeared a few months afterward.  The
"clack" occurs above 1500 RPM and is louder when the throttles are open.  It
is greatest when cold. Early on, when it was still mild, the engine builder
shrugged his shoulders unconcerned.  Now, I'm no longer under warranty, and
its worse
than when I drove over to him.  I no longer share his nonchalance.  I
initially figured it was just valve lash adjustment and did a quick
inspection and just turned the valve adjustment in 1/2 turn more, and the
sound disappeared but again slowly returned.  I have tried to identify the
location of the "clack" with a stethoscope/probe - no luck.  It
doesn't seem to be coming from under the valve covers, and sounds the same
regardless of where on the engine I probe.  Along the way, I replaced the
fuel pump-no
effect.  I changed from the stock exhaust to the GTS headers/mufflers-no
effect.  While I had the intake manifold off to switch to Webers, I replaced
all the lifters, thinking that one of them appeared to be "soft".  The sound
again went away for a month, but now has slowly reappeared.  Inspection of
the valve train showed no anomalies - no signs of any wear really.

I'm kinda out of easy trouble-shooting ideas - please give me a boost.