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Opeler
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Located under the vapor canister end cap or inside the canister.
Auto parts stores should have a 4" diameter vapor (charcoal) canister foam filter.
If the filter is too large, it can be trimmed to fit with scissors.
P/N: ACDelco A478C, Standard CF-1, WIX 42998, etc.

Vapor Canister Filter.jpeg
 

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Opel Rallier since 1977
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BTW, WGL, I checked my '75 canister and indeed the fuel tank vent line goes to the center port on the canister. So one more vote for the tank to the center port.

And, I pulled off the short hose from the side port of the canister indicated by tag #5 in the '74 TM pix above, and indeed, there is a flow restrictor in that hose. Its diameter is 2 mm (about 5/64").

And my canister has a foam filter in the end away from the nipples... and it is totally shot and falling apart. Tnx for the filter PN's Lindsay.
 

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Yes, that certainly seems contradictory!LOL

From your description above, it sounds like that threaded port on your brass tee pictured above goes to the bottom of the air cleaner housing. If so, then it sounds like your connection from the canister into the carb is not complete. There needs to be a canister-to-carb connection to go to a port on the side of the Weber carb (ported vacuum). See the red circled port in the pix in the 3rd post of the Turbobricks article linked above.

I am realizing now that the venting of the fuel tank (as fuel is drawn out) also goes via the canister in some of these canister systems. So that has to be part of all this. So your present connection from the air cleaner to the canister probably needs to stay for that function. And, I guess I am going to have to take one of these apart (after all these years) to see how the 3 hose nipples lead into the charcoal bits.

May I ask: Does the 'other' end of your canister (the end with no hose nipples) have any openings, with a foam or paper filter behind it?
Yes, the threaded part of the T goes into the bottom of the air cleaner housing and one hose from the T goes to the canister. There is no "ported vacuum" port on my Weber carb. The 3rd post you reference is for the Solex carb, which I do not have. The fix for the upgrade of a Weber is the T that goes up from under the air cleaner housing.

Yes, this whole thing started when I discovered that the eyesore of a can by the battery was actually important, so I removed it, cleaned it up and painted it, got some proper hoses and reinstalled it, then connected it up how I thought it should be, but then when I asked the question, I got so many different answers. Here are some pics of the process. I replaced the deteriorated foam at the other end with a nice piece of a scrubbing pad, which is basically to keep the charcoal from coming out:
 

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Opel Rallier since 1977
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There is no "ported vacuum" port on my Weber carb. The 3rd post you reference is for the Solex carb, which I do not have.
Mmmmm.... I think there is some confusion... IN my most recent post, I was not referring to the 3rd post in this thread by Kwilford... but the 3rd post in the linked Turbobricks thread.

Alternately, google for 'weber 32/36 ported vacuum' and look at the images.... there's all sort of pix of the ported vacuum port on the Weber 32/36.
 

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Mmmmm.... I think there is some confusion... IN my most recent post, I was not referring to the 3rd post in this thread by Kwilford... but the 3rd post in the linked Turbobricks thread.

Alternately, google for 'weber 32/36 ported vacuum' and look at the images.... there's all sort of pix of the ported vacuum port on the Weber 32/36.
Ah-ha!! Got it. I will study on this after work.
 

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Opel Rallier since 1977
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Roger.. To get it configured similarly to an original system, you would keep the present connection to the air cleaner, and add a connection from the presently blocked-off port on the canister to the ported vacuum through a restrictor.

Your distributor's vacuum advance may be connected to the ported vacuum already.
 

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Roger.. To get it configured similarly to an original system, you would keep the present connection to the air cleaner, and add a connection from the presently blocked-off port on the canister to the ported vacuum through a restrictor.

Your distributor's vacuum advance may be connected to the ported vacuum already.
Yes, the distributor's vacuum advance is connected to the port on the carb. Not sure if it matters but I do not have a choke on this carb. And my carb does not have a vacuum nipple at the blue circle, and I will not be drilling any holes into it.
After taking another look at the pic of my canister (before I removed it), I've concluded that the top port originally went to the gas tank, the middle port was blocked off and the bottom port went probably to the atmosphere, and maybe I need to again change my configuration. Makes me dizzy o_O Too damn many hoses going every which way...
 

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Vendor
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I understand your desire to get this right, but for what it's worth, most GT owners have deleted the charcoal cannister. If your tank lines are in good shape and you don't have any engine bay leaks you won't have any issues with gas smells in the car. I've owned 4 GTs and none of them had this system in place and I never had a problem with gas odors. These were obviously designed for solex carbs, which are almost extinct on GTs.
 

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I understand your desire to get this right, but for what it's worth, most GT owners have deleted the charcoal cannister. If your tank lines are in good shape and you don't have any engine bay leaks you won't have any issues with gas smells in the car. I've owned 4 GTs and none of them had this system in place and I never had a problem with gas odors. These were obviously designed for solex carbs, which are almost extinct on GTs.
That makes sense. I did get this car as a semi-project, so since it's overall in pretty nice shape, I find myself enjoying the tinkering around with that which is not in good shape, such as some of the engine compartment wiring, and that dog-gone canister LOL!!
Since I had the fuel pump replaced, I don't seem to have any oil leaks. The way the canister is set up right now, I'm not smelling any gas while idling, or driving, so maybe I should just leave well enough alone. Still, there is the challenge of exactly what to do with the canister (don't even think it), for others who might have the same questions and would love to get the exact answer and not have to fiddle around with it like I'm doing now.
 

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Opel Rallier since 1977
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One thing to know about the canister is that for cars with that item, the air into the canister via the canister filter, or via the air cleaner connection, is the source of venting to the gas tank as fuel gets drawn out. If the original fuel cap is in place (which will be an unvented cap for this system), then blocking the flow into the line from canister to tank blocks the air inlet. Then a vented cap has to be put in place. (One has to wonder how often this got removed and the line to the tank plugged, with subsequent fueling problems.)

WGL, your connection from the canister into your air filter is what is now pulling any gas vapors out of the charcoal, but there never is much vacuum there. The connection to ported vacuum is another means to draw vapors out of the charcoal at light to medium cruise condition, when that port has some level of vacuum; that will draw out more vapors as that vacuum level gets fairly substantial. At idle, neither will have any real vacuum to draw out vapors from the charcoal. When stopped with the car off, any expanding vapors from the tank will go into the canister and be trapped by the charcoal.

At this point, I think you ought to buy a Factory Service Manual for your year of GT and follow that. There are plenty on eBay. I have given you the info from the '74 FSM; I bet it aapplies ot other year swiht the 3 port canister but you could make sure. How the canister was connected when you got the car is totally meaningless, as you don't know who did what to swap any connections in the past.

Perhaps take the canister apart and finding out exactly how deep into the carcoal each connection extends. I'm going to make a SWAG that one will extend into the canister more or less deeply than the other 2. If I can find one, I will do so. As you say, it is always good to know the right way and how this are supposed to operate, regardless of whether you do it that way or otherwise.
 
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