Awfull Noise, Stuck/broken valve/lifter/something? Help!

[Jim Green]

Just when I thought I was finished, I was sitting at a
yellow light to turn left, gunned it when it turned
red to get out of the way, wham, this loud knock like
a hammer hitting my engine head has graced me with
it's presence.  The engine is a newly rebuilt MC-2
with rebuilt large valve head, with everything
properly torqued and a whopping 40 miles on it.  No
vacuum pump if you're wondering.

The engine runs perfect still, idles fine, I tested
compression, the lowest cyl was 130 psi probably
because the rings haven't seated yet.  The knock will
go away if you rev the engine then as the revs die
it's quiet.  I pulled the valve cover off because I
thought I broke the cam or something, everything looks
fine, all the lifters are in contact with the cam.
Peered into the cylinders through the spark plug
holes, the look fine from what I can see.  When just
turning the engine over with the coil disconnected it
sounds fine, tried pulling wires off injectors and
plugs with it running to see if that did anything, no
change.  Timing is still fine, set at 6 degrees btdc,
the belt hasn't jumped, boost is only at about 13 psi,
but I hardly let that happen since the engine is so
new.  Luckily I was only a few blocks from my house.
I'm going to replace the lifters tomorrow, but I doubt
that's going to help.  What the hell have I done this
time?  Please don't say I broke a rod or something
because I am sick of the bottom of my car.  I need a
Very Large Drink.

Thanks,

Jim Green
'89 90tq EFI, about to get it's NG engine back if it
doesn't behave.

__________________________________________________
Do You Yahoo!?
Send FREE Valentine eCards with Yahoo! Greetings!
http://greetings.yahoo.com