<VV> Engine noise question - sorry, long

[N. Joseph Potts]

It is quite possible you have inadvertently screwed an upper stud for a
(the?) head into the block too far, and now it is occasionally interfering
with the crank. Did any of the studs unscrew? If so, did you make sure it
was the specified length after screwing it back in? Of course, you must make
sure (this is harder) that the stud doesn't screw further in when you turn
the head nut on. Did you use new head nuts (less torque on the stud)?
     You can check this by measuring the height (above the head) of the
studs with the engine assembled and EVEN (carefully) remedy the situation if
you find it. Look for a low stud.
     Another possibility is that you have thrown a valve seat. Since your
valve seat doesn't appear to be reseating, a compression test will reveal
this very quickly.

Joe Potts
Miami, Florida USA
1966 Corsa coupe 140hp 4-speed with A/C

-----Original Message-----
From: virtualvairs-admin@corvair.org
[mailto:virtualvairs-admin@corvair.org]On Behalf Of ChiefTAM@aol.com
Sent: Friday, June 18, 2004 12:13 PM
To: virtualvairs@skiblack.com
Subject: <VV> Engine noise question - sorry, long


-  I originally sent this to Matt offline, but got to thinking he might not
check his mail for a while, and I need to decide a course of action by later
this afternoon, so I am sending it out to VV for a bit of advice on how to
proceed. -


I am sending this off list, as many others are at the convention.  I have a
question I wonder if you might give me some insight into.

You have responded to my reply's on fixing my 69 110 Convert. after it broke
two piston rings on the #4 cylinder while driving it from Iowa to Texas.  I
went in with the help of a NTCA member and pulled the engine apart, replaced
the
rod bearing on #4 and put in new rings on that piston, honed the cylinder
(everything still standard, under 50,000 on engine) and put it back
together.

After starting it back up, I had one lifter that made noise, needed to get
pumped up I guess, and after 5 minutes or so of idle, it did.  I drive the
car a
few miles around town last week, and it just purred.  I drove it last night
as well about 10 miles, getting it fully warmed up, making sure everything
was
OK to drive the thing to work today.  It ran well again.

This morning, I started out for work, 42 miles away.  The car ran
beautifully, until I came into town.  I stopped at a stop light, and as I
pulled away, I
didn't give it enough revs (4-speed) and it rattled like detonation twice
and
then took off.  A couple blocks down, just before work, I noticed it didn't
sound quite right, louder than normal.  I pulled into the parking lot at
work
and as I reved the engine above idle, I could hear a knocking, sounding like
it
was coming from the center of the engine.

I let the car sit for an hour and a half and went out to start it again.  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.

Now my problem.  I don't know what it is.  I don't think the detonation had
anything to do with it, as that sometimes happen if I don't rev it up enough
when taking off.  I certainly don't think it is a piston ring again, as it
is
making noise, and it really didn't before, just sounded a little off.  I
don't
think it is a rod either.  I would think that if it is a rod bearing, that
would make noise all the time.  We only replace one rod bearing, and I
believe we
got it torqued right, so I don't think it would loosen up.

The only thing that I can think of left is valve train.  Coming from the
center of the engine, I am inclined to think lifter.  I am wondering if the
problem might be a valve that is too tight, and after it got warm, it
started to
make a knocking or hammering noise.  Is that what they do or sound like?  It
is
hot here in Texas today, and so I know that the engine got warmer today then
it
has been since I put it back together.  I would think if a lifter is loose,
you would get more clacking of the rocker arms than sounding like it was
coming
from the center of the engine.  As an engine fully warms, the metal expands
and the valve would get tighter wouldn't it?

So, any ideas?  I am trying to decide if I should get a trailer and haul it
back home.  I didn't bring my sockets, but I could probably get some and
take
off the valve cover to see if one of the valves is too tight and loosen it
up.
I don't want to hurt anything further, especially if it is something simple
like a lifter.

I suppose there could have been some junk in the engine that got into a
lifter and plugged it up.  I did warm the engine up with new oil and filter,
and
then changed it again, so the oil should be good and clean now.  Don't
know......what do you think?

Todd Miller
Dallas