Expert: Kevin Pilotte - 11/8/2009

Question
Hello Kevin, I have a 1970 Javelin with a 258 6 cyl engine and a one barrel carb. Where does the vacuum advance hose go to? There is a port on the lower end of the carb(with eng running i don't feel any vacuum at idle) and one on the manifold just below where the cab attaches to it. When I attach it to the carb side it sounds like a model T idling. Or better yet where would the the two vacuum ports lead to?. and after that is routed correctly whats the best way to adjust the carb as far as mixture goes. Thanks in advance
Dennis...

Answer
You would want ported vacuum to the distributor, that's the port that has vacuum when you start to open the throttle and none at idle.
If the engine speed is too low, adjust it to the proper RPM.
If all other adjustments are correct on your carburetor, get the engine to operating temperature and slowly turn the mixture screw clockwise until the RPM just starts to drop, then turn the screw counter-clockwise to achieve the highest RPM.
The other vacuum port can run to a number of items, air cleaner, another vacuum switching valve,etc.
I do not have a vacuum diagram for your car. Sorry.