avs carb vacuum ports

[mac]

avs carb on a 440 in a 69 Daytona. does anyone have a pic of the vacuum port used for the vacuum advance? at idle the port being used is showing manifold vac and I would like to see ported but could not see another port to use.

 

[Big John]

 

[mac]

thanks John. that is the port being used but there is about 12" of vacuum at idle. will need to look into this a bit more.

 

[droptop]

Sounds like the plates are already open. That port should have little or no vacuum at idle. Sounds like you are not in the idle circuit.

 

[mac]

I am still looking for some info on the adjusting the "idle air bleed"? might be looking to deep.

 

[Meep-Meep]

Regarding the manifold vac at the ported port.. You need to advance your timing and drop the idle accordingly. Back off the idle speed screw until the throttle plates are fully seated then crank it in 1.5-2 turns. Start the car and see where your idle speed is. I will guess it's barely running if at all. If so, advance the timing using a light and hopefully you end up with 12 to 15 BTDC (assuming you have a mild cam and not a lot of cranking pressure). Big cam? Then you will likely be at 20 BTDC. Check total advance to make sure you are about 36-38 BTDC with vac advance disconnected and the hose plugged and make appropriate modifications to the distributor if you are not in spec. Check for vacuum at the ported port and you should have none or very little. The vac advance should add about 8 degrees to the timing if tested with a hand pump or hooked to manifold vacuum as a test. Vac advance hooked to the ported port you should have a lot of timing at part throttle - like 50 degrees - but that's OK under a very low load situation. The idea is when you roll the throttle open the ported signal falls off and the vac diaphragm reverts back to it's at rest position and the mech advance is now running the show. Hope this helps.