<VV> Single Carburetor - Better formatted

[Sethracer at aol.com]

Mike wrote:

Do  NOT  use ported vacuum, but draw directly from manifold  vacuum.
 
 
So Seth writes:


Mike  and I will have to disagree on this one, I guess. I believe you 
should  
give the distributor what it expects. The Corvair distributors (Turbo  
models  excluded) were designed to have a stable timing at idle based  on 
the 
initial  setting only, with no vacuum or mechanical advance.  Vacuum was 
only 
applied when  the throttle was opened, mechanical  advance at some higher 
RPM. 
You could do the  mod that Matt  suggested, eliminating the Vacuum advance 
completely. If the  initial  timing is set with this mod done, you won't 
have 
the stumble you   describe - if that idle drop is the culprit, and I think 
it 
is. Running  with out  vacuum advance, however, will impact gas mileage at 
part  throttle cruise.  Engine vacuum is a reflection of engine load. An 
engine  
with a light load can  tolerate extra advance and, as GM originally  
intended, more advance is better.  (Okay there is some question on an  
engine that 
is designed to NEVER ping, More  advance past a certain  point gives no HP 
advantage. I assure you the  Corvair engine is not  that engine.) Just 
short of 
pinging is where the Corvair  engine  lives a happy life. If you cannot 
find 
a "ported" vacuum source on  the  2GC, you should either look for another 
carb, or eliminate the  connection  entirely. GM built several dozen 
different 
2GC models  over 25+ years of  production. Models that fed vacuum at idle 
to 
the  distributor were designed to  work with that style distributor. (not  
ours). If you feed manifold vacuum  to our distributors, opening the  
throttle - 
which drops the vacuum signal, will  instantly retard the  timing - You 
already know the result of that. PS - Which  distributor  number are you 
using on 
the 110 motor? -Seth  Emerson