[NoVa-Corvairs] tech question

[Curtis Shimp]

Daniel:

A carb can have a leak at the base even if it is tighten snuggly.  The
hard, plastic insulator, assuming you have them below your carbs and if
not you should, make a poor sealing material.  They are too hard to be
compliant.  Additionally, some of the carb bases and/or the mounting pad
on the head can be warped.  You should have carb gaskets on both sides of
the insulator.  By the way, the carb gaskets need to be installed in a
specific way and have certain reliefs cut into them for the idle circuits
to operate correctly.  

Secondly as John MacMahon mention the other obvious place to look are the
two short, rubber tubes that connect the balance tube to each head at the
mounting pad for the carbs.  These can get hard with time and temperature
and not seal well or the tubes can pull partly or all the way out of the
rubber connectors.  Again as John mentioned I use a squirt of starting
fluid (ether) at the base of the suspected carb and listen for a rise in
rpm.  You have to be careful here not to let the ether fumes get up into
the top of the carb or the result will be a false positive.  The best way
to ensure this does not happen is to use the standard GM air cleaner with
good gaskets at the mouth of the carb.  Ether is VERY flammable so be
careful.

However, before you assume that your sporadic idle is a vacuum leak you
should check all of your carb linkages and idle screw settings first. 
Your comment that you have so little suction on one side may just mean
that you have the opposite side carb open too far and you are bypassing
the idle circuit.  This sounds like the most likely scenario but this is
another whole subject which would take more time to cover here than I
have now so I will have to send another note latter.  

You know, if I remember correctly I worked on your carbs at a I-95 rest
stop a couple of years ago.  I believe that problem then was more timing
than carbs but the car seem to run pretty well when we got done.

Curt

On Tue, 19 Jun 2007 22:06:03 -0400 "Daniel Goldberg"
<goldie at danielgoldberg.net> writes:
> Why would a primary carb that's snugly tightened have a vaccuum leak? 
>  
> 
> (The line to the vaccuum advance is also properly plugged up.)
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