Quadrajet question

[kna4977]

Have a quadrajet on a 72. The front vacuum port is plugged which I understand to be normal. It has one on the passenger side near the choke setup that is open and not capped. What is this supposed to go to or should it be capped? Here’s a pic.

[howzzzit]

It's called a diverter port. I have no idea what it would be used for, but I think it has vacuum at idle. Mine is capped.

[geezer#99]

Charcoal canister full time manifold vacuum port.

[1970cstblazer]

The one on the side of the carb is a manifold vacuum source for the air cleaner Thermac snorkel valve.

If you are looking for the utmost correct look, the TCS emission control system is missing, and it appears the lines to the charcoal canister are gone.

[howzzzit]

Originally Posted by geezer#99

Charcoal canister full time manifold vacuum port.

My quadrajet has a canister purge port on the front. It is ported vacuum. Anytime engine is off idle it activates the switch at the canister which in turns allows the canister pcv port to open and dump the fumes into the pcv port at the carb through a tee. I changed my old canister and added an external switch. New ones don't have it built in and it works great. No more gas fumes.

[kna4977]

Originally Posted by 1970cstblazer

The one on the side of the carb is a manifold vacuum source for the air cleaner Thermac snorkel valve.

If you are looking for the utmost correct look, the TCS emission control system is missing, and it appears the lines to the charcoal canister are gone.

Not sure why anyone would want a TCS system and I understand why people would remove them and throw them away. They seem like a PITA. Bet a complete working system is super hard to find today.

What did it all look like originally and where did the charcoal canister mount? Did all the 72s come with them?

For now I'm going to cap it off.

[howzzzit]

Originally Posted by kna4977

Not sure why anyone would want a TCS system and I understand why people would remove them and throw them away. They seem like a PITA. Bet a complete working system is super hard to find today.

What did it all look like originally and where did the charcoal canister mount? Did all the 72s come with them?

For now I'm going to cap it off.

Canister next to and below the battery. They were an answer to non-vented fuel tanks. The charcoal absorbed the fuel vapors instead of venting out the cap. My 72 is a C10 and I may be wrong, but I believe only 1/2 tons had the canister and smog setup that year. Someone will know for sure.

[1970cstblazer]

Originally Posted by kna4977

Not sure why anyone would want a TCS system and I understand why people would remove them and throw them away. They seem like a PITA. Bet a complete working system is super hard to find today.

What did it all look like originally and where did the charcoal canister mount? Did all the 72s come with them?

For now I'm going to cap it off.

You do realize that you can have the solenoid present, and all hooked up, and vacuum can pass through it as long as it is not electrically energized...

[1970cstblazer]

[geezer#99]

Originally Posted by 1970cstblazer

You do realize that you can have the solenoid present, and all hooked up, and vacuum can pass through it as long as it is not electrically energized...

Actually you get no vacuum thru it until you’re in high gear.

[1970cstblazer]

I'm not talking about an actual original functional system. I am referring to a "for appearances only" system. Verified with a hand vacuum pump/gauge, the solenoid on my 1970 allows vacuum through it when the system has had it's power source rendered inoperable. It looks 100 percent correct and allows full vacuum to the distributor advance can at all times when there is manifold vacuum available.