<VV> Engine noise question - sorry, long

[BobHelt@aol.com]

In a message dated 6/19/04 9:38:09 AM US Mountain Standard Time,
UltraMonzaWest@aol.com writes:

> If so....why didn't he hear it in the previous 50 miles of driving?
>
Well, as we all know, any speculation is simply a guess. And even that is
based on the info provided and how that is interpreted.

Todd reported the following........

At
idle, it sounded pretty normal, certainly like it is hitting on all
cylinders.
As I would flip the throttle, raising it above idle, it would make the
knocking sound again, coming from the center of the engine, I believe.  The
knocking would get louder the higher the revs, and disappear, or almost
disappear at
idle.

So here we have a noise that seems to get louder as the RPMs increase. So
maybe Todd couldn't hear the noise previously because of road noise at speed.
Remember he heard the noise AFTER he got to town. So maybe the noise was with
him
all the time he was at speed and he just copuldn't hear it above all the
other noise.

Now it would seem logical that the inertia at high speed would throw the rod
end closer to the stud end, so if there was a little extra play in that
bearing, the rod would move closer to the stud as the RPMs increased. Who
knows?
Maybe the burst of detonation mentioned caused just enough bearing wear
(actually
deformation) to increase the clearance just enough to have the rod hit the
stud (assuming that the stud was inserted into the crankcase further than
stock.
So that, along with temperature expansion effects cause the hitting.

Also looking at the situation as a whole, what are the probabilities? Rings
and piston? doubtful. Maybe the piston lost a piece, but why would that occur?
Head? doubtful. Lifter/adjustment? possible, but don't fit the description of
the problem. The engine seems to run just fine otherwise he reports. Junk on
top of the piston (so it hits the head)? Possible, but not included in the
description. This could be a cause however. What's left? Possibly a stud that
turned when he removed the head, so that when the stud was reseated, it was
inserted too far into the crankcase. This is also a possibility and the one I
think
caused the problem. But who knows? This is a guessing game for sure.

Regards,
Bob Helt