Charcoal canister connection

[srwilson]

I'm just about to get things in order again under the hood after swapping my intake and carb.

My charcoal canister had previously been remove by P.O. but he saved it and I have it. I was thinking of re-installing it, however I'm not sure just how to connect it back up.

From the manual I see 3 lines lines connect to the 79 model canister. I have connections for 2. One going back to the gas tank and one going to the front of the 34ADF carb. In the manual I see that originally two of the lines went back to the carb. But I don't have that option.

Can I just hook up two of the line and plug the left over one. If so which one of the two that are suppose to go to the carb should I connect to carb and which one would I plug?

Would it be best at this point to leave the canister out? If so what to do with the port on the carb? Cap it? If I cap it the engine doesn't run as smooth. I thought of adding a "T" and running it up to the port on the bottom of the air breather. Good idea or bad idea? What about the line going back to the tank? Cap it? Leave it alone?

Thanks for any help!

[Fi8spider]

I think the third line you are looking to connect goes to the inlet manifold. There should be a barb on the side of the manifold.

[bradartigue]

If you cap it the engine doesn't run as smooth because the can itself delivers a fixed quantity of air. If you cap the port, adjust the mixture very slightly leaner to compensate. Once capped your car will smell like gas from time to time.

Here is the port diagram from carb to canister (and other ports)

http://www.artigue.com/adf/

The smaller "3rd port" on the canister goes to the intake manifold, it keeps constant airflow through the canister even when the carburetor turns its ports off during throttle rotation. So if you follow, you're getting air into the engine from both the manifold port and the carburetor, resulting in a richer mix if you block off both.

[srwilson]

Thanks, Brad! I understand what you're saying on the lean/rich topic but I'm still a little confused on the "3rd port" .

My canister has 3 nipples/ports: two on the bottom and one on top. One of the 2,on the bottom, goes back to the fuel tank, and the other goes to the carb, right? The one port on the top of the canister also goes to the carb, right? However My carb only has the one port that I believe connects to the port on the top of the canister (according to your diagram). The second port is missing on the carb that would go to the other port on the bottom of the canister.

So which one is suppose to go to the intake manifold? That is where I'm getting confused.

I really appreciate your help!

Oh and the diagram is Great! Thanks so much!

[bradartigue]

NONE of them go to the Intake Manifold, that was an error.

I had to refer back to the shop manuals, look at 102.01, page 10-79 and onward, "Fuel Tank and Lines" and you'll see the variations. With an ADHA or ADF or ADFA and a square three port canister:

The top port on the canister goes to the right top port on the carburetor when you are facing the mixture screw.

There are two ports on the bottom. The one facing the radiator/grille (the front) goes to the fuel vapor line coming from the fuel tank. The one facing the firewall (the back) goes to the carburetor port located on the left upper back, manifold side, furthest and to the left of you if facing the mixture screw.

NOTE that the charcoal canister should have a little black hat on it, next to the top port. That hat is a metered orifice; if the hat is missing and the 1/2" hole underneath is exposed then you have too much air entering the system.

[srwilson]

NONE of them go to the Intake Manifold, that was an error.

I had to refer back to the shop manuals, look at 102.01, page 10-79 and onward, "Fuel Tank and Lines" and you'll see the variations. With an ADHA or ADF or ADFA and a square three port canister:

The top port on the canister goes to the right top port on the carburetor when you are facing the mixture screw.

Check, got that.

There are two ports on the bottom. The one facing the radiator/grille (the front) goes to the fuel vapor line coming from the fuel tank.

Check, got that too.

The one facing the firewall (the back) goes to the carburetor port located on the left upper back, manifold side, furthest and to the left of you if facing the mixture screw.

This is where I'm having trouble. I have this on the canister but not on my new carb. So I was wondering what I should do. I guess the obvious thing would be to go search for the part that connects to the carb and hook it up. But I was also thinking just to keep the canister off but was unsure what to do with the remaining lines from carb and fuel tank. I was thinking of plugging them. But again wasn't sure that was a good thing.

NOTE that the charcoal canister should have a little black hat on it, next to the top port. That hat is a metered orifice; if the hat is missing and the 1/2" hole underneath is exposed then you have too much air entering the system.

Got that part too!

Thanks again, and if you have any suggestions I'd be more than happy to hear them!

[bradartigue]

Either bypass it altogether or just plug that connection on the canister. Shouldn't be a problem.

[srwilson]

Thanks, Brad. I'm going to plug the port on the bottom of the canister for now.

I'm still looking for a brass insert for the Vacuum Advance port on the carb. Do you have a source for that? I looked on the Pierce Manifolds site but couldn't find the part.

[majicwrench]

If you don't have the right carb and other assorted pieces, leave out canister or plug. What you don't want to happen is sucking directly from carb bowl or tank. Most everything has valves which open when engine off to allow vapors into canister. Then they shut when engine running. Otherwise you suck directly from tank or carb.
Keith

[srwilson]

Thanks Keith.

I think I understand the the mechanics/function of the Charcoal Canister a bit better now.

It would appear that the canister has two chambers, one filled with Charcoal at the bottom, and a empty chamber at the top.

Vapors enter the canister through both of the bottom two ports; one from the fuel tank, and one from the Carb (non vacuum side). The Top port on the canister is connected to the vacuum side of the Carb and is what draws the vapors from the fuel tank & left over vapors in the carb back into carb and on into the manifold, thus eliminated or helping to eliminate fuel smells in the car. The weighted top on the canister regulates the amount of air that can enter the carb's port.

If what I think is correct then I should be OK to cap off the bottom port on the canister. It is simply a excess vapor line for the Carb itself. Maybe a little more gas smell from the carb but the air regulation from the canister into the carb should be just fine. And that was what I was worried about in the first place.

[4uall]

Here is an awesome link

http://fiatspider.com/f08/viewtopic.php ... &sk=t&sd=a

[majicwrench]

THe goal of the canister is not to reduce odor, but to reduce the amount of HC (u8nburned fuel) escaping.

You still need to beware......that you are not directly sucking fumes from tank into carb/intake. Don't have fiat diagram in front of me, but you need SOMETHING to prevent that from happening. Perhaps that is the two way valve I see in some pictures. The transfer of tank fumes to the canister generally takes place with engine off. Then when running, it suck a tiny amount of air thru the carbon and burns the HC.

I'm speaking genericly here, cause like I said, I don't have a fiat diagram in front of me. but the line that draws the vapors back to carb/intake is always a ported vacuum source. Otherwise the varying mixture would make for an unsteady idle.
IN other words, if you have the car idling and pinch off the line, should not affect the idle.
Keith

[srwilson]

Here is the picture from the manual. I don't see anything between the carb and the top of the canister except a line.

[majicwrench]

It needs some sort of valve....soemwhere. Lots of carbs had the valve inside carb. without some sort of valve, you are sucking fumes from the bowl/tank, thru canister, back into intake. I'm gonna snoop thru some old carb books...

[srwilson]

if you have the car idling and pinch off the line, should not affect the idle.

It affects mine. Not sure what that means but it does.