INTAKE MANIFOLD VACUUM LINE REMOVED, 318 HIGH IDLE

[temsinc]

I installed a Black Bandit Vacuum Brake Booster Pump on my 1970 Barracuda w/318. I am not sure what to do with the vacuum port on the fuel intake manifold.

I initially installed a plug in the vacuum port and the car ran rough with intermittent back fire. So I removed it and reinstalled the 90 degree port and left is open and then the car idled at 1500 rpm.

There was no direction in the instructions as to deal with the open vacuum port. Any feedback is appreciated.

Darcy

 

[moparleo]

There should be no effect when the port is plugged. Did you put the proper fitting bolt in the threaded hole ? If the car is backfiring or running rough with the port plugged, you have a vacuum leak elsewhere. Take a spray bottle with WATER not any flammables and while the engine is running spray along the intake to cylinder head joint and look for changes in rpm. Also at the base of the carb and any other vacuum lines you may have.
What was the purpose of this "Brake booster pump?" Was there a problem with the original booster ? Is this 318 stock or has someone modified it somehow ?