Need Help Verifing Quadrajet Vacuum Lines / Ports
 

I have a 1969 K10 with 350 V8 w/Quadrajet carburetor, 4 speed manual, PS and PB. Truck was built in Janesville. The stampings on the carburetor body are: 7045583 YZ 1276. I believe the carburetor decodes as follows: 4MV, 1975, California only.

I can’t find a vacuum diagram for the truck. And even if I did, because the carburetor is not original to the truck I couldn’t determine if everything is hooked up correctly.

So, I need help determining what all of the vacuum lines are for and that they are connected to the correct ports. I have included several photographs that have the lines / ports numbered.

#1a / 1b: Distributor vacuum advance line. Is 1b connected to the correct port? Should it be connected to a ported or direct vacuum source?

#2: ?

#3a / 3b: ?

#4: ?

#5a / 5b: PCV line. Is 5b connected to the correct port?

#6: ?

#7: Brake booster vacuum line. Is 7 connected to the correct port?

Thank you in advance.

Re: Need Help Verifing Quadrajet Vacuum Lines / Ports
 

1. Correct. Hooked to manifold vac port.
2. Manifold vac for charcoal filter.
3. Both manifold vacuum for choke pull off.
4. Same as 3.
5. Pcv hook up.
6. Ported vac port.
7. Correct. Manifold vac for booster.

Re: Need Help Verifing Quadrajet Vacuum Lines / Ports
 

You should make a steel tubing fuel line.
Rubber hose can leak and ruin your whole day.

Whether you run ported or manifold vac to your distributor, let your motor decide.

Re: Need Help Verifing Quadrajet Vacuum Lines / Ports
 

Thank you for the information.

I’ve included a photograph of an air cleaner assembly I just purchased. I was told by the seller that it is correct for my truck. Would the open rubber hose on the assembly be connected to one of the plugged vacuum ports?

Thanks.

Re: Need Help Verifing Quadrajet Vacuum Lines / Ports
 

Looks like stock.
Do you have the pipe from the exhaust manifold to the air cleaner?
IIRC that hose hooks up to a manifold vacuum port.

Re: Need Help Verifing Quadrajet Vacuum Lines / Ports
 

The air cleaner hose connects to #2. On later carbs that have either the hot air or electric choke, then it goes to a manifold vacuum port.

That is part of the THERMAC system. Needs the hot air stove on one of the exhaust manifolds and the already mentioned metal pipe to connect the two. Common failure is the thing with two hoses(essentially a thermostat). It is supposed to send vacuum to the flapper valve in the nozzle until the air temp in the cleaner is IIRC 105*F.

Hose between 1a and 1b, your dizzy vac advance hose, it normally more the size of #4 or the hose on the air cleaner and doesn't use the clamps.