<VV> Engine issue

jvhroberts at aol.com jvhroberts at aol.com
Mon Nov 29 21:38:03 EST 2010

I NEVER had a cylinder to cylinder mixture issue on any of my Corvair 
engines. Proximity of the cylinder to the carb doesn't really matter on 
the stock setup. The volume of the cylinder far exceeds the manifold 
volume, and since only one cylinder breathes through the carb at a 
time, the mixture is actually rather even. Now, side to side, there may 
be issues due to synchronization problems.

John Roberts

-----Original Message-----
From: Bill Bicknell <bicknell at cfanet.com>
To: 'Michael Kovacs' <kovacsmj at sbcglobal.net>; VIRTUALVAIRS at CORVAIR.ORG
Sent: Mon, Nov 29, 2010 9:05 pm
Subject: Re: <VV> Engine issue

I understand that lean mixture can cause detonation.  However, the #2
cylinder is the shortest path from the carburetor and so I figured it 
the least likely to get leaned out.

-----Original Message-----
From: Michael Kovacs [mailto:kovacsmj at sbcglobal.net]
Sent: Monday, November 29, 2010 6:13 PM
Subject: Re: <VV> Engine issue

It was like this when you purchased it. Is there a possibility that #2 
getting a full charge of fuel/air? In other words a lean mixture? Could
something be restricting the intake manifold up stream of #2. This is a 
shot, but one cause of detonation is a lean mixture.

I assume you are using the proper plugs. Sounds like you did all the 
stuff to cool the cylinders.


----- Original Message ----
From: Bill Bicknell <bicknell at cfanet.com>

I have recently acquired a 1962 Rampside with #2 piston burned from what
appeared to be detonation.  All other pistons/cylinders looked normal.
After replacing the piston and honing the cylinder to clean up the 
transfer, the same #2 piston became burned due to detonation.  The 
would idle fine at 14 degree timing, but with lack of power.  At about 
degree timing it seemed to run reasonably and with good power, but with
pinging noticeable when starting from a dead stop.  I have replaced the 
piston again, this time with a different used cylinder  and still 
notice the
detonation from start, but haven't driven it much until I can learn more
about what's going on.

When I replaced the first piston, I also changed rings and bearings and
timed the camshaft to the crankshaft as accurately as I could determine.
This seemed to be a challenge.  I used keyway positions checking with
machine squares.  Since such advanced distributor timing is required, I 
still wondering if this is an issue.  What is the best technique for 
timing operation?  But why did the same cylinder position have the 
problem -

I have been rebuilding conventional water-cooled engines for decades, 
for a
while professionally, so I know engine basics but something is eluding 
here.  Perhaps something unique to Corvairs.  Knowing that
pre-ignition/detonation can initiate from carbon build up and/or sharp
edges, I wire brushed all combustion areas, valves, and valve cavities
clean prior to assembly.  All fins were cleaned to avoid hot spots.  The
sheet metal air deflectors are in place.  The thermostat properly opens 
air deflector valve when the engine heats up.

Can someone help with some suggestions?

Bill Bicknell


Cell phone: 970-218-1352

This message was sent by the VirtualVairs mailing list, all copyrights 
are the
of the writer, please attribute properly. For help, 
mailto:vv-help at corvair.org
This list sponsored by the Corvair Society of America, 
Post messages to: VirtualVairs at corvair.org
Change your options: 


More information about the VirtualVairs mailing list