<VV> Single Carburetor more info

[Frank DuVal]

How did you balance the carbs, with just the idle mixture and speed screws?

You need to start with the shop manual and the linkage adjustments.

A simple vacuum leak can be found with propane or starting fluid sprayed 
on the suspect leak area. Be mindful of ignition points, both the actual 
point sin the distributor and anything else that sparks and ignites gas.

Most vacuum leaks on Corvairs are the balance tube rubber hoses to 
heads. And hoses off the balance tube to PCV and other systems. I assume 
you do not have a vacuum modulator on a manual shift, but is the hose 
still hanging somewhere?

And if you do not have a balance tube, well that is a problem.

BTW, you used the actual correct term, but everyone here would know the 
term choke pull-off. Good for you.

Most carb balance issues are linkage, not vacuum.

I haven't used a uni-syn in years. I just listen, but that is after 35 
years experience. I did just get one in a trailer load of parts 
Saturday. Now I will find my old one...

An extra engine would just confuse the situation more at this point.

Frank DuVal


On 4/22/2013 5:34 PM, John Ingram wrote:
> The reason for all of this is that I could not get the carbs to
> balance,  I know it sounds like a simple vacuum leak.  I have
> searched everywhere, Plugged the vacuum brake connection  and every
> other vacuum connection, and cannot find it.  I used different
> balancing tools, the normal floating ball type got good normal
> readings, but it would not idle at all and when it revved up and
> smoothed out one exhaust pipe would be hotter than the other.  The
> carbs were rebuilds with new manifold seals, where else could it have
> a vacuum leak?  Two carbs would be enough, this engine is in a VW
> Bus, no need to go fast, I just want it to run.  The idle problem is
> finally cured and the power is good once I'm moving along.  Just this
> one last problem.  I have not taken the heads off but  even though
> the compression check did not show a weak cylinder, there could be a
> crack above the intake valve,  in the intake port. (?) I'm sick of
> working on it, I'd like to drive it for a while before I take it
> apart again.
> JI