Checking vacuum on 440 Six Pack

[KillerBee]

Gonna try to finish tuning my Six Pack carbs this weekend.

My setup is a fairly close to stock 440 Six Pack with .528 solid cam and  4 speed.

No power brakes so the rear of the intake has a plug in it.

The distributor is locked out with light springs so I have no vacuum advance hooked up, both the distributor and carb port are plugged.

I need the correct source to hook up my vacuum gauge to adjust my center carb's idle mixture screws.

Which port do I use?

I don't believe the carb port for distributor advance should have vacuum at idle so should I use the plugged port in the rear of the intake?

anyone know what size is that plug?

Thanks.

[Chryco Psycho]

the rear plug for the power brakes or the PCV line will work not sure on the plug size . 1/4 " pipe maybe

[73Chally]

I picked up an Autometer vacuum accessory pack at Autozone for mine.  I think it was about $6.  It included the fitting to screw into the manifold, the plastic tubing to run back to the gauge, and the fittings to attach to the back of the gauge.  For the gauge I just bought a basic Autometer vacuum gauge, which I keep stashed in the glove box, and just pull it out when I want to see what it's doing.  The center ash tray on the dash makes a perfect place to put it.