what is????
07-10-2004, 09:19 PM
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what is????
I have a 78 vette and I am doing a bunch of engine mods. Can someone tell me what the cannister is on the drivers side firewall, pretty low that a bunch of hoses come out of. I'm not using some of the hoses anymore and have just plugged them off. I'd really like to know if I'm screwing anything up by plugging the hoses.
07-10-2004, 09:49 PM
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It's called a carbon(charcoal) canister. It's part of the fuel evaporative control system. It controls the emission of vapor fumes from the fuel tank to the atmosphere. (Just took that out of my Haynes manual) Mine's not hooked up and runs just fine. 
Last edited by wogs73; 07-10-2004 at 10:00 PM.
07-11-2004, 04:30 PM
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wogs is righht thats an EVC. Its real function is to allow the fuel tank to breath and trap vapor from tank and feed it to carb to burn instead of venting to atmosphere. Some models trap carb fuel bowl vapors too. What I'm saying is if you plug the line to the tank you just plugged the tank vent. If you hear a sucking sound when you open the fuel cap you'll know why. Possible loss of fuel press too. Or on a hot day if the fuel cap farts you'll know your fuel vent is plugged up.
I just replaced this on my '74. Yea, small PIA. NAPA still sells'm for $55 as I didn't trust my 30 yr old charcoal.
The vapors that boil off inside tank (and sometimes carb) are trapped inside the EVC charcoal. When engine is running well above idle a ported vacuum sucks the trapped vapor into carb. The ported vacuum enters well above primary venturi throttle plate so it won't affect idle mixture - read that it could stall engine if at idle. EVC has a connection to atmosphere -stock one on bottom, NAPA connection is on top - to draw purge air through charcoal and into carb (or tank).
Hope this helps ya. cardo0
I just replaced this on my '74. Yea, small PIA. NAPA still sells'm for $55 as I didn't trust my 30 yr old charcoal.
The vapors that boil off inside tank (and sometimes carb) are trapped inside the EVC charcoal. When engine is running well above idle a ported vacuum sucks the trapped vapor into carb. The ported vacuum enters well above primary venturi throttle plate so it won't affect idle mixture - read that it could stall engine if at idle. EVC has a connection to atmosphere -stock one on bottom, NAPA connection is on top - to draw purge air through charcoal and into carb (or tank).
Hope this helps ya. cardo0
07-11-2004, 06:13 PM
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My canister has all of the fuel lines connected from the tank, and the hoses that used to run to the carb i just removed, that way my tank is vented, all my vacuum accessories are hooked up, and everything's happy. I run a speed demon, but i've got the same amount of vacuum ports you do.
