charcoal canister on 76 Cordoba

[Clarksdale68]

Is there any harm plugging that thing up? One hose comes from the gas tank, and two go to the carb. But there are no fittings on my Edelbrock for the 2 carb hoses from the canister. I'm thinking the fuel fumes shouldn't be allowed to float around the under the hood.

Thanks!

 

[Hemi Rebel]

Your tank will need a vent though. If there are 2 vapor lines(would love to see a picture of the canister) i would hook one of them up and i guess plug the other one.

 

[Clarksdale68]

Thanks Hemi Rebel ... Baltimore, huh? I went to UMBC and am a Maryland native. Here in MI for work. Here's the canister ... the middle line comes from the gas tank and the two outside go to the carb. This is the Thermoquad (no longer installed) with the lines in place, one to the upper part and one to the base.

 

[73coupe]

i would also like to know what to do with the 2 lines that are supposed to go to the carb on the stock set up?? im also using an edelbrock carb ,,, so far i just capped them off ,,, but i would like to know how it actually is supposed to be. thanks

 

[moparmarks]

The line that goes to the top of the carb is a bowl vent line. Can plug that one. Take the other line to the manifold vacuum port on your new carb just like it was on the old one.

 

[72RoadrunnerGTX]

The line that goes to the top of the carb is a bowl vent line. Can plug that one. Take the other line to the manifold vacuum port on your new carb just like it was on the old one.

The ¼” purge line on a three nipple canister is not connected to straight manifold vacuum. That port on the Thermoquad is a timed port, vacuum present only at part to full throttle, split evenly between the two primary bores as the purge function is a metered flow.

 

[moparmarks]

I stand corrected. Wasn't sure if that port was manifold or timed.

 

[RustyRatRod]

It looks functional. If it is and you disable it, look for fuel mileage to decrease.

 

[Clarksdale68]

The ¼” purge line on a three nipple canister is not connected to straight manifold vacuum. That port on the Thermoquad is a timed port, vacuum present only at part to full throttle, split evenly between the two primary bores as the purge function is a metered flow.

Thanks, Roadrunner and Moparmarks. I guess I should just put a T-fitting on the ported vacuum on the Edelbrock - one line to the distributor and one to the canister? I wouldn't have guessed that's where that line from the canister went, but now it makes sense that that's how the canister is purged of vapor. Thanks again.

 

[72RoadrunnerGTX]

Thanks, Roadrunner and Moparmarks. I guess I should just put a T-fitting on the ported vacuum on the Edelbrock - one line to the distributor and one to the canister? I wouldn't have guessed that's where that line from the canister went, but now it makes sense that that's how the canister is purged of vapor. Thanks again.

The problem you run into using the vacuum advance port on the aftermarket carbs is that it is designed as a vacuum signal, not as a calibrated flow. Typically it is ported to one primary bore only. The purge function is basically a calibrated vacuum leak, needs to be distributed evenly between both primaries. Only the OEM carbs are going to have a port configured correctly for the 3-nipple canisters. The one year only 72’ 4-port canister works better for carbs without the dedicated purge port. The purge line is tee’d into the PCV line, and metered/controlled by a diaphragm operated valve signaled by being tee’d into the vacuum advance line. No special port required for nominal canister function.

 

[Clarksdale68]

The problem you run into using the vacuum advance port on the aftermarket carbs is that it is designed as a vacuum signal, not as a calibrated flow. Typically it is ported to one primary bore only. The purge function is basically a calibrated vacuum leak, needs to be distributed evenly between both primaries. Only the OEM carbs are going to have a port configured correctly for the 3-nipple canisters. The one year only 72’ 4-port canister works better for carbs without the dedicated purge port. The purge line is tee’d into the PCV line, and metered/controlled by a diaphragm operated valve signaled by being tee’d into the vacuum advance line. No special port required for nominal canister function.

Oh boy ... more complicated than I thought. I wonder if I can find on of those 1972 canisters.

Silly question, but can you just vent the fuel tank to the atmosphere?

 

[Dobaroy]

I haven't run one of those canisters in years and yes I just vent the tank to the atmosphere. There is no vapor smell at all. The Edelbrock Carb . . . I personally think it is the only way to go. Good luck with it.

 

[moparmarks]

I didn't know that about the 72 cans. I probably have a few of them.

 

[Clarksdale68]

I haven't run one of those canisters in years and yes I just vent the tank to the atmosphere. There is no vapor smell at all. The Edelbrock Carb . . . I personally think it is the only way to go. Good luck with it.

I think that's what I'll do ... Where did you vent to the atmosphere, Dobaroy - at the tank, midway, or leave the hose intact all the way to the engine compartment? Thanks!

 

[Dobaroy]

Clarksdale, we took all the hoses and the can out and just left the small line coming from the tank, vents right there where the canister used to be, and thats how it's been for a lot of years on all 4 cars. Let me know if you want a pic and I will get you one.