<VV> One more head question e-mail

[N. Joseph Potts]

Generally, a blown head gasket produces a hissing noise. Something you can
try before pulling the head (it's cheap, easy, and very unlikely to help):
retorque all your head nuts/studs. If you don't have access to the torquing
sequence or the specification, you've GOT to get a Shop Manual, even if that
means buying another copy (they're cheap, and readily available from Corvair
vendors). The things holding the head down are those upper studs you found
chrome nuts on, and the studs that the rockers are mounted on.
     This is something you'll have to do when putting the head back on
anyway, so learn how now, and give it a chance to do magic for you.
     Chevy did not install any acorn nuts. Their presence on your car
SUGGESTS that the head has already been off at least once in the car's life,
but of course, their presence does not positively PROVE that they have been.
If the threads underneath are clean, it will improve your chances of
removing the head nuts without turning the studs out of the block. I turned
one stud out in a recent head replacement. I cleaned up its threads, put on
a LITTLE anti-seize compound, screwed the stud back in to the prescribed
length, put the head on, and drove away happy. Acorn nuts are on my head
studs, you may be sure.
     By the way, I believe a meaningful leakdown test can be performed from
a 10-gallon or larger air tank pressurized to 150psi or more. The suspect
cylinder can be tested, and possibly even compared to an adjacent cylinder,
on one tank if you're quick about it.

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: Sunday, April 11, 2004 7:10 PM
To: virtualvairs@skiblack.com
Subject: <VV> One more head question e-mail


OK, I know that I have asked a lot of questions about by low compression
problem and head removal, and I just need to get on with tearing it apart,
but I
have just a couple of more questions.

I was out this afternoon taking off accessories, removing shrouds, and
spraying the head and exhaust bolts with penetrating spray.  While doing
this, I was
able to get my fiancee out to turn over the engine while I looked from
underneath with the rocker cover off.

I got to admit, this engine really looks clean, at least under the rocker
covers.  I suppose this should be the case in an engine that has not hit
50,000
miles yet.  As we turned the engine over, I heard no unusual mechanical
noises,
the thing just spun over freely.  Nothing hitting, clacking or clanking.
The
valve train went up and down, around, just like it was supposed to.  I could
not tell any difference in rocker arm travel between #4 cylinder, the one
with
only 60 lbs. compression, and the other two cylinders.

As I can't do a leakdown test, I am just guessing that the problem has to be
one of 4 things:
a valve seat just loose enough to cause low compression but not out enough
to
cause anything to bind or allow the perceptable close of the valve
a hole in a piston
a broken piston ring
a bad head gasket
 The engine seemed to run smoothly when I started it the last time, seemed
to
run up OK, and then I notice a miss like it was loading up on gas.  I didn't
notice any preceptable smoke, and the engine has never used oil.

Now, with a hole in the piston or a broken ring, would it not smoke?  I
believe it was Patiomatt that said you could put some small amount of oil in
the
spark plug hole, run the compression test again, and if it goes up, it's
rings,
stays the same, its valves. I think I will try this before I tear the head
off
it I can find something small to get some oil in there.  Was it an ounce or
so?

How common is a broken head gasket?  I don't suppose I could be lucky enough
that this would be the problem.

Someone mentioned putting on acorn nuts on the upper head studs to keep the
ends of the threads clean.  Was this done by Chevy?  I just looked at mine
and
they have the chrome acorn nuts on them.  Do you take these nuts off first
by
going shallow with the socket and then take off the head nut?