Howdy gang,
2.3L 4 cylinder sohc Volvo penta engine twin Solex downdraught carbs
Anybody here happen to know if the two brass plugs on the intake manifold under each carb can to be used as a vacuum port.

Looking down into the rear carb it doesn't seem to have the gas flowing when running like the front one. low power
it has new carb kits with pumps

I'd like to install a vacuum gauge.
I've been told you can balance them using the vacuum.

I have a unisync and a snap on vacuum balancing tool--it is a clear plastic cylinder with a red sliding piston inside and a vacuum hose on each side - The carbs are balanced when the red piston is in the middle.

I was wondering if I could adapt the two brass plugs port to each side of the tool
thanks
hank