Manifold Vacuum port on GM TBI unit
i was wondering where the manifold vacuum port is on the GM TBI (i have the Howell-CA EFI kit)? is it port J; port J is left of the PCV port while looking towards the back of thr truck which Howell suggests to plug up since it's not used. or can i get manifold vacuum from the port comming out of the intake manifold which is right under the TBI throttle linkage?
i took the vac reading from both ports and the pressure dips to about 5in right when i increase the throttle but returns steadily back to about 20in when i hold the throttle at any position. isn't manifold pressure suppose to drop as throttle position is increased?
basically i'm trying to look for a manifold vac source for my HEI distrib. have it on ported vac right now and want to just play around a bit...
83 CJ7 258/T5