Charcoal Canister
May 26th, 2018, 12:02 PM
#1
Registered User
Thread Starter
Join Date: May 2018
Posts: 471
Charcoal Canister
Hi,
Just cleaning up the car today for the first time, and actually noticed this before buying it, but one of the lines going to the canister is disconnected and plugged with a bolt. Is there any advantage or good reason to do this?
If not, is there anyway to clean or verify that the canister is in good working before reconnecting the line, if I even should reconnect it? Maybe if the car is running fine I should just leave well enough alone?
Just cleaning up the car today for the first time, and actually noticed this before buying it, but one of the lines going to the canister is disconnected and plugged with a bolt. Is there any advantage or good reason to do this?
If not, is there anyway to clean or verify that the canister is in good working before reconnecting the line, if I even should reconnect it? Maybe if the car is running fine I should just leave well enough alone?
May 27th, 2018, 06:56 PM
#2
Registered User
Join Date: Sep 2011
Location: Plano, TX
Posts: 1,846
Well, that's a bit of a rabbit hole.
The line that's still connected goes to the gas tank, so gas vapors are being caught in the charcoal. The line that's capped should go to a connection on the base plate of the qjet. It's metered ported vacuum. Folks usually disconnect stuff because they just don't know what it does. It doesn't cost any power and doesn't affect the tune to any appreciable degree.
Without a charcoal canister you need either a vented tank cap and/or an open vent under the car. It's basically acting like a buffered vent right now.
The main problem is the charcoal is small granules in a cloth bag. The cloth deteriorates over decades. In bad cases it'll fall apart and the engine will suck a bunch of small charcoal nibblets through the carb. Not good. You can take the canister out, there should be a filter on the bottom since that's the original style, and see what condition the bag is in. You can get service replacements from Rock Auto or anywhere else that look a little different but function the same.
It doesn't hurt anything to leave it like it is, but I think it's a decent emissions control thing. You state inspection might care, depending on where you are. E.g. in DFW we're supposed to have the stock emissions controls in place. The techs don't know what they are, so they just look for something obviously hanging disconnected, but have no idea if something is gone entirely.
The line that's still connected goes to the gas tank, so gas vapors are being caught in the charcoal. The line that's capped should go to a connection on the base plate of the qjet. It's metered ported vacuum. Folks usually disconnect stuff because they just don't know what it does. It doesn't cost any power and doesn't affect the tune to any appreciable degree.
Without a charcoal canister you need either a vented tank cap and/or an open vent under the car. It's basically acting like a buffered vent right now.
The main problem is the charcoal is small granules in a cloth bag. The cloth deteriorates over decades. In bad cases it'll fall apart and the engine will suck a bunch of small charcoal nibblets through the carb. Not good. You can take the canister out, there should be a filter on the bottom since that's the original style, and see what condition the bag is in. You can get service replacements from Rock Auto or anywhere else that look a little different but function the same.
It doesn't hurt anything to leave it like it is, but I think it's a decent emissions control thing. You state inspection might care, depending on where you are. E.g. in DFW we're supposed to have the stock emissions controls in place. The techs don't know what they are, so they just look for something obviously hanging disconnected, but have no idea if something is gone entirely.
May 27th, 2018, 07:59 PM
#3
Registered User
Thread Starter
Join Date: May 2018
Posts: 471
Interesting. I will check again tomorrow, but I thought the hose still connected looked like it went to a connection around the top of the engine. Perhaps someone connected the lines wrong and just did this as a patch repair when it wasn't working properly.
I think I would rather have it connected and working properly if possible. I will have a look at the existing canister and if it seems to be in decent shape and working properly reconnect it, and if not maybe try an aftermarket replacement. Worst case I can always just put it back the way it is now.
I guess maybe one of the first things to do is verify what hose goes where...
I think I would rather have it connected and working properly if possible. I will have a look at the existing canister and if it seems to be in decent shape and working properly reconnect it, and if not maybe try an aftermarket replacement. Worst case I can always just put it back the way it is now.
I guess maybe one of the first things to do is verify what hose goes where...
May 28th, 2018, 10:00 AM
#4
Registered User
Join Date: Sep 2011
Location: Plano, TX
Posts: 1,846
When looking at the front of the carb from the front of the car, the hose going to the charcoal canister should be connected to the vacuum fitting on the base plate on the right side, should be 1/4". The fitting on the left side is for PCV, should be 5/16" or 3/8". There is a ported vacuum signal for distributor advance on the front of the body on the right side.
The angled fitting on the left side should go straight into the vacuum break for the choke/air flap.
There's a couple of fresh air fittings on the back on the air horn that were used for various things - hot choke supply, air cleaner ambient switch, etc.
Everything else is manifold and there's been tons of different hookups and shadetree mechanics are known to do creative modifications.
A repop service manual isn't terribly expensive and has all this detail. Just note that the spines are really weak so they fall apart easily.
The angled fitting on the left side should go straight into the vacuum break for the choke/air flap.
There's a couple of fresh air fittings on the back on the air horn that were used for various things - hot choke supply, air cleaner ambient switch, etc.
Everything else is manifold and there's been tons of different hookups and shadetree mechanics are known to do creative modifications.
A repop service manual isn't terribly expensive and has all this detail. Just note that the spines are really weak so they fall apart easily.
Thread
Thread Starter
Forum
Replies
Last Post
rhett838
General Discussion
39
July 24th, 2015 12:23 AM
