Quadrajet Problem Solving > Diagnose a Quadrajet carburetor problem
Missing Vacuum Port? what do i do?
72Campcust:
So, i have a QJet '77 Cali emissions Carb..this is what the front of mine looks like.
Cliff told me that i need to hook my Dist Vac Advance to the port to the right of the fuel filter, just above the idle screw...well...mine doesn't have that?? ??? I have seen pics of older/other carbs that do have a port on the front right side of the carb so i understand what im looking for..
I currently have my vac advance hooked up to the port just above the fuel line filter housing (how it came when i bought the truck), but it is a "Ported Vacuum" spot.. so my vac advance is getting vacuum at idle.
there are three Manifold ports in the bases plate, the center one is hooked to my PCV, there is one just to the right of it (capped off, seen in the pic) and one to the left of the left side idle screw, also capped off.
So two questions: why is this carb different (no port on the front right)
where/how do i hook up my vacuum advance?
If where i have it is right, ive read in some schematics that there might have been a inline delay valve or check valve of some sort?? Obviously when ALL the vac lines where hooked up it would have been way different..
any help is appreciated..
Ethan1:
Looks like it is in the correct place to me.
Cliff Ruggles:
Currently you have it hooked to FULL manifold vacuum.
The lower left fitting in the baseplate is ported vacuum, but may have a "bleed" off port and not work for the distributor, if ported vacuum is needed for the vacuum advance. The bleed off slot can be filled in with epoxy, if it is present, providing strong ported vacuum to that fitting.....Cliff
72Campcust:
--- Quote from: Cliff Ruggles on January 27, 2013, 05:59:48 AM ---Currently you have it hooked to FULL manifold vacuum.
The lower left fitting in the baseplate is ported vacuum, but may have a "bleed" off port and not work for the distributor, if ported vacuum is needed for the vacuum advance. The bleed off slot can be filled in with epoxy, if it is present, providing strong ported vacuum to that fitting.....Cliff
--- End quote ---
Cliff-- thanks, ive been scratching my head on what to do.. How do I know/identify if it has a bleed off port? How do i know/confirm if i need "Ported Vaccum" for my carb/distributor... i was under the assumption that i did??
ohh.. and you where spot on.. I plugged the hole in the choke housing and cleared up the idle issue.. silly me ;)
Cliff Ruggles:
A vacuum gauge hooked to the port with the engine running is th easiest way to determine which port does what.
You can also remove the carb and look at the lower fitting to see if it has a bleed off port to reduce vacuum as the throttle plates open.....Cliff
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