440 Six Pack Outboard Carburetor Question

[MoparHonda]

I have a '70 Plymouth 440 six pack. The end/outboard carbs are off the car. I put a vacuum pump on the inlet hose of each carburetor and pumped up to about 15 - 16 psi. The throttle plates open slightly and then it loses vacuum and they close back shut.

(The vacuum pump and connecting hose are working correctly, it holds vacuum when I plug the end of the hose.)

How far are the throttle plates expected to open when vacuum is applied?
Are the end carbs expected to hold vacuum once vacuum is applied?

 

[68 HEMI GTS]

You will have to plug the kill bleed on the passenger side Venturi with your finger before your test will work

 

[MoparHonda]

Thank you, 68 Hemi GTS, where on the passenger side venturi would I find the kill bleed?

 

[68 HEMI GTS]

It's down by the booster, the side the diaphragm srews on. You can see it if you look. They should open and hold vacuum then.

 

[moper]

The vacuum that continues to open the secondaries is actually the pressure drop from airflow within the carbs themselves. It's a drilled passage like was said- near the PS booster in each outboard.