Andy:
While you don't specifically say so, it sounds as though you are
still
running with your original cam chain, sprockets, and tensioner. These
parts are
cheap enough that anyone who builds an engine should replace them as
cheap insurance
against needing to go back into the engine in a couple thousand miles.
When upgrading your engine as extensively as you have, the
components in the
engine are under more stress. When those components are 30 years old and
have gone
many miles, their lifetime is appreciably shortened.
It sounds as though you already know what is wrong - the cam
drive is getting
sloppy for some reason. You can use a hose like a stethoscope and
localize the noise
better and perhaps confirm your diagnosis.
If you did not replace the cam drive chain and sprockets when
you did the rebuild,
I would do so now should you need to go into the engine, even if they
are fine for the
moment. But then I am anal about this stuff.
Cheers,
Vance
-----Original Message-----
From: owner-6pack@autox.team.net [mailto:owner-6pack@autox.team.net] On
Behalf Of Andrew Packard
Sent: February 02, 2006 8:23 AM
To: 6pack@autox.team.net
Subject: I may have a serious problem
Hello list:
<snip>
Last weekend I adjusted the valve clearances and changed the oil. I had
been about 800-1000 miles since the rebuild, so I removed the regular
oil
and replaced it with synthetic, as recommended by the machine shop that
rebuilt the bottom end and did the head work. The valve adjustment made
the
engine run smoother as the gaps were high in several of them. Shortly
into
my first test drive, I began to hear a sound that sounded like rocker
activity with the valve cover off, but about 2X as loud. I thought that
perhaps a securing nut was loose on one of the rocker arms, so I
readjusted
the valves last night, only to hear the same noise while running. In
the
garage, the noise is most prevalent at 2000 rpm and sometimes appears at
1000rpm for a short time. While driving, I can hear it again at higher
rpms
on the freeway. With my head under the hood, I revved the engine enough
to
create the noise and tried to trace it. Although it sounded like rocker
noise, it seemed to come from the front of the engine, perhaps at the
end of
the crankshaft. It's difficult to pinpoint with the fan spinning and
sounds
certainly getting deflected around the engine bay, but that's my best
guess
and worst fear. The timing chain was in good shape when I did the
engine
rebuild, but I did consider the timing cover as a source of the noise.
Any thoughts are invited and appreciated.
Andy Packard
|