General Category > Quadrajet Carb Talk and Tips

73 Trans Am Quadrajet ported vac. port question..seems blocked

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jlutz455:
Hi,

I checked the small port to the right of the fuel inlet ( as viewed if standing in front of car looking at engine) with a vacuum gauge at idle and driving around. There's no vacuum at all making me think it's been blocked.  I want to hook this port up to my MSD distributor but where should I check if this is blocked and can I drill it out ?  Carb # is 7043263

jlutz455:
forgot to add the vacuum line that is under the idle solenoid bracket is where the distributor is connected.

Cliff Ruggles:
Remove the baseplate and verify that the passage leading up to the fitting isn't blocked.

Look at the baseplate to make sure it has a vacuum supply just above the throttle plates that leads to the same passage.

If someone installed the wrong baseplate it may not be drilled for ported vacuum.....Cliff

jlutz455:
Ah..makes sense. I'll check this weekend. Thanks Cliff!

jlutz455:
wanted to update... Looks like my baseplate on my car is from an auto trans car as it has a port for the auto transmission modulator to the right of the EGR port.

The ported vacuum port in the body didn't connect to the baseplate so referencing another post in this forum, drilled a .050" hole just above where the throttle plate opens (referenced the other side primary horizontal slot position as to where to drill) Now I have ported vacuum as verified by a vacuum gauge and a vacuum "T" while driving.  I get 10-12 in of vacuum now at part throttle cruising. Thanks Cliff :-)

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