This charcoal thing

Does it need to be connected to carb or intake to draw tank fumes? I have it unconnected at the moment. Don't want to connect it and slow me down.

 

That goes to snorkel of air cleaner

 

Says to carb on the canister.

 

Not to a vacuum port. It's like an old road draft crankcase vent.

 

I remember those. Good, I can leave it vented the way it is. There are no heavy fumes exiting it anyway.

 

Since I have no carb vent port provisions or air cleaner snorkel, I'll just leave it tucked out of site!

 

Larry is right. On the 71, the canister connects to a port on the front of the carb base plate. It doesn't affect performance either connected or not. If it is not connected, you will need to replace the fuel cap with a vented one if all the vapor hoses from the tank are still connected and the canister hose is blocked off.

 

I had it connected, abt 20 years ago, to a port on a 750 Holley vacuum secondary carb. Sold that carb to a Chevy guy.
It's not capped off, just open to atmosphere. Everything is still connected as factory with this exception. I guess this is my vented gas cap alternative now....
The charcoal canister was cleaned and replaced.

 

It would be attached to a fitting in the air snorkel (non GS) or air filter base (GS), outside of the filter element. I've never seen it attached to the carb.

 

71 manual. Looks like qjet has a vacuum nipple for the canister hose.

 

Yeah. The 71 attachment is a 1-year only thing.

 

On 77+ m4mc qjets there is an extra 3/8 nipple for it.

 

That's where I had mine plugged in.

 

If you'll look I think you will find the bottom of the canister is open. Fumes from the tank are adsorbed by the charcoal and a slight vacuum from the engine intake system moves air through the canister from the bottom, drawing off the vapors and burning them. This keeps gas fumes (mostly) out of the garage. Modern systems have two solenoid valves controlled by the ECM, one on the purge line to the engine, and one on the large vent line (often but not always at the bottom of the canister). They also put a pressure transducer in the tank and then use the two valves to positively control tank pressure and vapor accumulation and flow so nothing gets out.

Jim

 

Interesting. Now that I think about it, I have ever so slightly, smelled gas in the garage. Popped hood, felt all fuel lines, crawled under car and checked all fuel pump lines also to tank,....nothing but dry.

Must be the underside of that canister.... or just that big 830 Holley with no choke.

 

You do often get some evaporation out of the carb bowls. Another reason they went to EFI. As long as the canister is large enough it will usually handle the tank, provided you drive the car regularly.

Jim