Vacuum ports on a Quadrajet

[hinkv10]

I just installed a SMI rebuilt Quadrajet in place of an old Edelbrock 1406 on my 305. There are more vacuum ports on the Quadrajet then on the Edelbrock and I'm wondering if anyone knows where I should hook everything up. I put the brake booster on the back in the same place it was on the Quadrajet. There is another small vacuum port at a 45 degree angle that I hooked up the vacuum advance on the distributor to. The pcv valve went to the lower one on the front. Lastly I have one that is hooked up to my th350 trans that I put somewhere, can't remember off the top of my head.

I guess I'm wondering if I installed the vacuum advance and tranny line in the correct locations. Sorry for no pictures and a bad description. I looked in my book and couldn't find anything that looked like my quadrajet. Thanks in advance

 

[Jims86]

I just installed a SMI rebuilt Quadrajet in place of an old Edelbrock 1406 on my 305. There are more vacuum ports on the Quadrajet then on the Edelbrock and I'm wondering if anyone knows where I should hook everything up. I put the brake booster on the back in the same place it was on the Quadrajet. There is another small vacuum port at a 45 degree angle that I hooked up the vacuum advance on the distributor to. The pcv valve went to the lower one on the front. Lastly I have one that is hooked up to my th350 trans that I put somewhere, can't remember off the top of my head.

I guess I'm wondering if I installed the vacuum advance and tranny line in the correct locations. Sorry for no pictures and a bad description. I looked in my book and couldn't find anything that looked like my quadrajet. Thanks in advance

Vac advance is the bottom port on the drivers side front of the carburetor, PCV is the large port on the rear. Do you have emissions equipment on the truck, or is it stripped bare?
If its bare, you can plug off the un needed ports.
If you have an electric chock, ther is usually a vacuum port on the choke tha runs through hard lines to the exhaust crossover in an OEM manifold, but otherwise, you can run a line directly the the port on the top rear pass side port on the carb air horn.

 

[chengny]

The actuating line for the TH350 modulator can go either straight to the intake manifold (there's usualy a tap point right behind the carb mount) or to an up-ported tap on the q-jet.

Vacuum advance line comes from the factory hooked up to a manifold port on the Q-jet but there are many different views on that.


Manifold ports on the carbureator are the ones down low.


Look at it this way;

Instead of trying to find a vacuum line for each port on the carb to attach to, identify what each vacuum line goes to and then select either a manifold or ported tap.

If there are any left over nipples on the carb, do as Jims86 suggests and cap them off.

 

[hinkv10]

Thanks, I switched the trans vac line up one of the higher ports or as you refer to them as up-ported. The rest are at the bottom. I should be good to go. Right?

 

[hinkv10]

Ok, I followed Jims86's advice and she is running a lot better. I included a couple of pics. I don't believe that all the ports down on the bottom of the carb are ported. Originally I had the port in the rear of carb that is at a 45 degree angle being used for the vacuum advance. The pic shows how it is now with the cap installed.

 

[hinkv10]

The previous pic is a manifold vacuum source. As soon as you unplug it the rpms go up and it advances the timing.

I plugged the vacuum advance into the port on the drivers side front which I am pointing to

 

[hinkv10]

The one with the white ziptie is the trans modulator or whatever you call it

 

[hinkv10]

The truck is running much better now and I think I have the timing all figured out. I do have a question on timing but I'll make another post. \

My question is from the pics, does it look like everything is hooked up correctly? I put the brake booster in the back and the pcv in the front. I don't see the harm in reversing those two and the brakes feel good. besides the hose will only go that far.

I don't want to hook up the vacuum advance to a manifold source. From what I've experimented with, I can't see any reason to do so.

Ps the timing is set to 14 degrees and has no stumble anymore.