<VV> Corvair 110 sounds like 10 lb hammer

[chaz at properproper.com]

Hey Guys ~

Hi again ~ I've been busy with a new place ~ with a GARAGE finally!!!

Unfortunately, my formerly sweet-running Vair obliged me with a malady
and is now laid to temporary rest in her new garage:

After over 5000 miles of smooth-running bliss, the loudest noise being
the fan and the air rushing over the windshield, all of a sudden it
sounded like 10 lb hammer on an anvil.

The banging is in synch with the RPM, driving and then at idle, 1:1,
maybe 2:1 with RPM, but definitely in synch with the RPM.

Being in a bad area at night, and AAA taking almost a half hour to
answer my call, I drove about a mile home (AAA answered after I was
safely home.)

The drive was smooth except the rapping noise, and even in 4th gear at
25 MPH, and had good power although I did not push it too hard.

Twice, the noise went away for a few seconds with no noticeable change
in power, just back to her former purring.

I thought maybe a dropped valve seat that re-seated for a moment, but
the compression is (right side) 130/90/130 and (left side) 110/100/110
(1-3-5/2-4-6)

There is no noticeable noise or resistance when I turn her over with the
fan belt or with a wrench.

There is also no noticeable noise or resistance when I crank her over
with the starter (with the coil wire off) ~ she sounds "normal" ~ just
smoothly cranking over.

Tomorrow I may pull the right head where the source of the banging noise
seems to originate, but I figured a little theory might help me see what
I might find when I open her up?

So, what do you think?
Thanks!
Charlie