<VV> Single Carburetor

[John Ingram]

Seth,
I have done a similar setting and the idle does go down when I  
disconnect the vacuum hose.  So, there should be no difference at  
all?  I did get good results when I set the timing at idle but it  
then it went way over advance at high rpm.  Is this "above the  
throttle plate" vacuum port normally used in stock chevy use?
Thanks,
JI


On Apr 22, 2013, at 3:31 PM, Sethracer at aol.com wrote:

>  johnvi at cloud9.net writes:
> I have a 65 110 that I have rigged with a single Rochester 2 barrel
> Carb.  Runs fine, idles fine, the problem is the engine doesn't have
> much low end torque, once I'm moving along it is okay but off the
> line I need to keep the revs up.  I think the drop in vacuum from a
> carb that may be too big is throwing off the timing, the distributer
> vacuum retards the timing when I press on the gas to start out.  Does
> anyone have experience with these single carb applications?  any  
> ideas?
>
> John - Do a test. Install a timing light and check the advance  
> setting at idle. With the car idling, remove (and plug) the hose  
> that connects to the vacuum advance unit on the distributor.  
> Disconnect it at the distributor end. Does the idle speed and/or  
> the idle timing setting change? The Corvair distributor is design  
> to have no vacuum advance applied at idle. Depending on where you  
> are pulling the vacuum from the Carburetor, you may be supplying a  
> high vacuum signal. As soon as you step on the throttle, that  
> vacuum would drop - and the distributor will go to retard - and the  
> engine will stumble. There should be a port on the Carburetor that  
> enters the throttle bore above the throttle plate and therefore  
> provides vacuum advance only when you come up off idle. That, and  
> resetting the initial advance, will cure the stumble, I think.  -  
> Seth Emerson