I have a 355 with a holley 750 DP. The carb has a vacuume on the front passanger side of the carb. I belive this is a kick down vacuum. But i have a 700r4 transmission that has a cable kickdown. There are two vacuum lines on that side one goes to the cruise control box (which i dont use), and another sneaks downs the drivers side of the transmission. But im sure it doest attach to it. Any advice on what i should do with the vacuume port on the carb would be helpful.

 

On a 700R4, there isn't any vac fittings (unless somebody got slick and rigged a vac switch to run the TCC) I'd follow that line and see where it really goes..and why it is there. My first guess is that it is the body's vac line for the heater/ac system.

Otherwise, there are only two types of vac on the carb, full manifold and ported. The ported one should be on the metering block, passenger side, just above the idle mixture screw. It goes to the distributor's vac advance can. The rest of the vac fittings are down low, on the throttle plate.

For a 3rd gen, you need two large diameter manifold vac ones..one for the power brake booster, and one for PCV/Canister Purge...typically you only get one large vac port on the carb and have to use a pipe fitting on the manifold for the other.

That leaves the small diameter full vac fittings on the carb. You need one for the body's vac system (HVAC, etc, etc.) Another for the Cruise Control system, And the rest are for anything else you might want (like a vac gauge in the pillar)

 

Ok, my next question is does every distributer have a vac advance on it, cause i dont see one on mine.

 

No, not all distributors have vacuum advance.

 

Welp, if you don't have a vac advance, then you are either:

1.) Using a computer controlled distributor (On a GM HEI, it has the weatherpak conectors on the base)

You can get away with this. On a GM computer you can have the computer running advance only (I've seen this done on a TBI computer that's been reprogrammed.) But I don't see the point in doing this..if you have already removed the ECM from controlling the fuel, why bother leaving it in at all?

2.) A distributor with mechanical advance only.

With a straight mechanical advance distributor, that's all it can do..curve ignition advance based on RPM by use of springs and weights. It works. But having a vac advance running off the ported vac from the carb works better for a street car, since it adds a few degrees based on vac signal in addition to the mechanical curve (better part throttle response)