Charcoal cannister

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1974-318

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Hi. I have a 74 Duster with cannister as shown. It has 1 line going to top of carb port, and the purge line going to port at base of carb(Carter BBD). I'm going to be switching to a 4 barrel Edelbrock which does not have the carb bowl vent port and the only port the purge line would fit is marked for pcv valve. Can I tee the purge line into the pcv line and just cap off carb port on the cannister ?
Next question is, should this have a purge valve attached somewhere on the purge line? Is it built into the cannister?
Thanks

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If you are changing the carb I suspect you live in an area that you do not have to smog you car or get "safety" checks.

If that is the case you can most likely cap off the lines unless they provide the breather for the tank.

The PVC runs off of manifold vacuum and as such makes a controlled intake manifold leak that the carb tuning accounts for.

The charcoal canister if "Yed" into that line MIGHT introduce another manifold leak that maybe the carb can not be adjusted for.
 
Thank you. Not sure if they provide the breather for the tank.
Isn't the purge line currently getting manifold vacuum where it's connected at the base of the BBD carb?
Not trying to argue your point, I just really have no idea how this stuff works.
 
Probably, but what I don't know is if the canister has some type of restrictor in it or if the carb has an orifice to limit the amount of leakage
 
Could I use the brake booster port on the manifold or get a carb spacer with a pcv port built in? I think maybe one of those options would work.
 
1974-318 said:
Could I use the brake booster port on the manifold or get a carb spacer with a pcv port built in? I think maybe one of those options would work.
Click to expand...

Based on what I think I you are doing, I was in your spot several years ago with the exact question. I reached out to a couple of knowledgable emission members and received a solution with an explanation. It was over PM’s so not easy to dump into a thread.

Send me a PM with your email and I’ll copy them into an email for you.
 
H22A4 said:
Based on what I think I you are doing, I was in your spot several years ago with the exact question. I reached out to a couple of knowledgable emission members and received a solution with an explanation. It was over PM’s so not easy to dump into a thread.

Send me a PM with your email and I’ll copy them into an email for you.
Click to expand...
thank you. I think I sent you a pm..lol. It came up as a conversation, hoping thats a pm. If not, can you send me a pm and then I can reply to you in the correct format
 
Good idea. Significant credit goes to slantsixdan who helped me out back in 2016. In a nutshell here is it:

You can connect the hose from the canister's purge port to the carb's power brake vacuum port, but not just directly point-to-point. You will need to put in a purge valve (ie: Borg Warner CP104 Canister Purge Valve). That valve gets spliced right into the hose that runs from the canister's PURGE port to the carb's power brake port. Put a T in your distributor vacuum advance hose and connect a hose from that T to the purge valve's small vacuum fitting. When tuning your engine, make sure the distributor's basic timing and the idle speed are both adjusted correctly so that there is vacuum in that distributor vacuum advance hose only above idle, not at idle.
 
No reason to plug off anything, the ’73 and up three nipple canisters used a dedicated ported (above the throttle blades) purge connection on the OE carbs. Without the OE carb you can tee into the PCV line but will need to place a restriction in the purge line of about .030”. Anything bigger will mess with the mixture calibration. It won’t purge as fast but will purge and not affect engine efficiency.

Optionally, you can run a ’72 four nipple two-stage purge canister, if you can find one in good working order, for a full purge rate. Tees into the PCV and vacuum advance lines.
 
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