Vacuum source for distributor? 67 400

[Flye]

67 400, 442. Relatively stock from what I can tell, but it has a stock vacuum advance HEI from a 78(?) Olds.

I just replaced a later model Quadjet with a 67 Olds model Quadrajet.

QUESTION:

What should be the vacuum source for the distributor advance?

This 67 carb doesn't have nearly the vacuum lines coming off of it as the later model.

I have one vacuum in front at base, and there is a outlet/inlet on the right (Passenger) side at the choke, but I didn't know if it was supposed to have some sort of warm air tube there, or if that was vacuum. Other than those two possibilities, I don't see anything else.

It also has a line coming up, which I assume is for the modulator (but I wouldn't bet my life on it). THAT line was attached to the newer carb up front.

The one on the side? Get a fitting and pull a source from the manifold? Other?

Any help?

[joe_padavano]

Originally Posted by Flye

67 400, 442. Relatively stock from what I can tell, but it has a stock vacuum advance HEI from a 78(?) Olds.

I just replaced a later model Quadjet with a 67 Olds model Quadrajet.

QUESTION:

What should be the vacuum source for the distributor advance?

This 67 carb doesn't have nearly the vacuum lines coming off of it as the later model.

I have one vacuum in front at base, and there is a outlet/inlet on the right (Passenger) side at the choke, but I didn't know if it was supposed to have some sort of warm air tube there, or if that was vacuum. Other than those two possibilities, I don't see anything else.

It also has a line coming up, which I assume is for the modulator (but I wouldn't bet my life on it). THAT line was attached to the newer carb up front.

The one on the side? Get a fitting and pull a source from the manifold? Other?

Any help?

The trans vac modulator (in addition to other vacuum operated accessories such as power brakes and A/C) need to be connected directly to manifold vacuum. If that means installing a vacuum tap in a manifold port, do it.

The distributor vacuum advance can be connected to either ported or manifold vacuum, whichever runs better. Ported vacuum (which is likely what you will see at the port on the front of the carb) is taken from a port just above the throttle plates. It is nearly zero at closed throttle, but as soon as the throttle plates uncover the port, ported vacuum becomes the same as manifold vacuum. You can determine if the tap on the front of the carb is ported vacuum by connecting a vacuum gauge to it. With the throttle closed at idle, it should have near zero vacuum. As you open the throttle it should jump up then track manifold vacuum. If vacuum at the port is high at idle, it is manifold vacuum.