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]

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

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

[72Campcust]

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

Cliff-- I hooked a vacuum gauge up to the port you suggested, when i throttle the engine up the vacuum climbs in correlation with RPMs. Do i still need to take it apart to see if it has the "Bleed Off" you mentioned? I'm hoping to avoid taking it all apart, unless the chances are pretty good that this does have the bleed off.. (carb #17057512). Am i testing it right by revving the engine up and watching the vacuum gauge..

[Cliff Ruggles]

The vacuum reading should go to full vacuum right off idle, and mimic what is seen on a manifold vacuum source.  The bleed off port reduces signal, so the readings are lower....Cliff

[72Campcust]

Thanks Cliff, If i remember right the vacuum pressure climbed with throttle input.. so, guess i need to plug the bleed port..

hopefully last questions..previously you mentioned that the bleed off slot can be filled with epoxy.. can i plug the bleed slot without taking the carb apart, IE just pull the carb off the manifold and flip it over and fill in the bleed slot..or do have to disassemble to get to it.

is it obvious what I'm supposed to plug with epoxy?

thanks

[72Campcust]

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

Is it obvious what i need to plug if i take the carb off of the manifold.. or do i need to disassemble the carb to do this..??   

[Cliff Ruggles]

Just remove the two long screws in the back and the screws holding the baseplate to the main casting, it will come right off for repairs/modifications....Cliff

[72Campcust]

Just remove the two long screws in the back and the screws holding the baseplate to the main casting, it will come right off for repairs/modifications....Cliff

Thanks for the help..hopefully the last question..

Pulled apart..now..which hole do i plug with epoxy??
Top right is the vacuum port i was using, this is view from top


this is bottom side of it..

[72Campcust]

TTT...

[Cliff Ruggles]

The round hole just aft of the flat slot is the bleed off hole....Cliff

[72Campcust]

The round hole just aft of the flat slot is the bleed off hole....Cliff

Thanks... Im guessing you mean this hole..(where the pencil is)

[Cliff Ruggles]

The round hole inside the bore just aft of the slot that provides ported vacuum.....Cliff