Marine: Boating, Sailing, PWC, GPS and Navigation - Help with 4.3 L w/cobra outdrive

Hello I need help with my 1986 Sea swirl. It has a 4.3 L w/ 2 barrel carb with a cobra out drive.

One problem I am having is I have a possible missing vacuum line?

If you are looking at the top of the motor, to the left of the carbuator there 2 holes for vacuum lines, on the intake manifold. If you look at the holes they are side by side, the line left goes to the carb. The right hole is empty but is pulling air with the engine running. Where should this hole connect? Or should it be caped off.

I just tuned up the motor, new plugs, wires, points; cap, rotor, oil & oil filter the works.
I set the dwell to 38 as stated in the manual and timing to 2 degrees BTDC. The motor is running real rough; when I plug the hole (missing vacuum line) the motor runs better but still not totally smooth.

Any help would be greatly appreciated…

No vacuum advance - just an internal mechanical flyweight. Possibly a vacuum driven accessory? I would at least cap it until I found a place for it.