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Carb vacuum pipes?

limeyboy

Active Member
I have two pipes from my manifold going into the Holley.
I think one is for the choke ( the one with the brass fitting) but I'm not sure what the other one is about?
The brass fitting was rattling about so I've "modified it", and the second brass fitting is not original I'm sure, so now assume she will run a little richer as there should be less of an air leak ( though she has always run very very well and starts very easily).
Also the fitting on the right with the Blue cap on it?
Any ideas?

20210513_162741 (1).jpg
 
This is how a choke works on a holly. The carburator suck air through the choke housing but that air has to be filtered , so the other tube is mounted to the aircleaner flange on the inside of the aircleaner. So , clean air goes to the manifold , heats up , and goes to the choke spiral/housing which also heats up and so it controls the choke function.
That other fitting is ported vacuum , I think , and is for the distributor. IMHO.

Verstuurd vanaf mijn SM-A605FN met Tapatalk
 
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The blue capped connection is for timed ported vacuum used for the vacuum advance on a distributor. This is different than just basic ported vacuum which comes from a port above the throttle plates in that it has no vacuum at idle but kicks in when using the throttle. It is designed to help eliminate off idle bogging under acceleration. Depending on distributor you may or may not want to use this connection as opposed to the standard ported connection. I think that black hose is connected to the basic ported vacuum connection at the top of the carb.
 
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