I have a TH400 hooked up to my 73 455 with an Edelbrock intake. Can anyone tell me where the vacuum line off of the transmission connects to with this setup? Thanks for help.

 

The TH400 needs full manifold vacuum. If the manifold has a port go directly to that port. If no intake port then a port off of the carburetor that is below the throttle plate providing full vacuum including at idle.

 

^x2^

Should be two 1/8 NPT vacuum ports on the backside of the intake manifold. Passenger side for the transmission vacuum modulator Driver side for the brake booster.