Charcoal Canister hookup for your car (Cure that gas stink!) - Ford Muscle Forums : Ford Muscle Cars Tech Forum
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post #1 of 7 (permalink) Old 05-26-2008, 09:38 PM Thread Starter
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Charcoal Canister hookup for your car (Cure that gas stink!)

Installing Charcoal cannister on my 79 F100 2WD is rather modified from stock.

A very mild 460 swap with a 4x4 Comp Cams camshaft, Performer intake, Edelbrock 800 AVS carb, and a dual snorkel 5.0 Mustang air cleaner. Of course the emissions items were removed years ago.

This past summer, I was driving the truck daily to work as my daily driver was down for repairs. The main office secretary would often comment that she liked my truck but wondered why "it smelled like gas". After a drive in warm-to-hot weather, the truck would have a gas odor when it was parked for a few hours.

Enter, the charcoal canister. This little gem is often tossed. Older Fords don't even have this. There are several varieties, some have one hookup to the gas tank, others have several hookups, while later charcoal canisters are computer controlled. The box in question I used is from a 1979 Bronco. This box is rectangular in shape, and the control valve has several ports on it.

I felt this box was easiest to work with, and would do the 'most good' in terms of quenching the stink. The ports are fairly easy to figure out with a chart similar to this. I created this from an emissions chart for a Ford engine, but I've dumbed it down to only the charcoal canister connections.

Looking down on the Purge CV (CV), the connections are fairly simple, from left to right.
Fuel T goes to the fuel tank vent line. This line allows the fuel tank to vent to the charcoal box as the tank empties. Most Ford vehicles in the 70s have this line in the engine bay, older vehicles do not in some cases.
The next port over is what I would call the "turn on" port. When vacuum is applied to this port, the charcoal canister is in 'purge' mode. This port goes to the "E" port on a Ford carburetor. My Edelbrock does not have an E port, (emissions), so I approximated and used the ported vacuum port. This only has vacuum above idle. Inline with this is a "VCV", or a vacuum control valve. You can see it here in this picture.

It's the blue manifold fitting on top of the thermostat, with vacuum hoses going in and out. This VCV only allows vacuum to flow through to the Purge CV once the engine is over a certain temperature.. In this case, 120 degrees. This piece is in place to stop the engine from stumbling from the slight extra fuel and vacuum 'leak' at a cold start.
The next port over, second to last on the right, goes to the PCV valve. PCV valves are available with two ports, a large and small port. The large port goes to the base of the (in my case) Edelbrock carburetor, in front center, while the small port on top goes to the Purge CV. This is the vacuum that does the work, emptying, or 'purging' (hence the name) of the charcoal canister. You may be wondering how this hose doesn't cause the engine to run rough, as it's a vacuum leak. Enter the Vacuum Restrictor (V REST).
If you get a full setup from a junkyard vehicle, you'll see the vacuum hose on this port is in two pieces with a small plastic fitting inline. Don't lose it! This is a Vacuum Restrictor. It restricts the vacuum the Purge CV sees. Think of it as a piece of ice stuck in a straw. Without this, you could create one with a small round piece of barstock with a 3/16" hole drilled in the center. The actual V REST is visible on the left most vacuum hose, It's light blue.

Lastly, visible in the same picture, is the bowl vent line. This hose goes from the carb to the bowl vent. Some Edelbrock carburetors (1400) are drilled for this with a port. All other Edelbrocks have a boss for the fitting, but are not drilled. If you remove the top plate and drill carefully with progressively larger bits, you can insert a piece of tubing into the carb top plate, and recreate this port.

This port allows air in and out of the bowl vent, but through the charcoal canister. There is also a Thermal Vacuum Switch (TVV) that only allows the bowl vent to open when the carburetor, and bowl vent, is over a certain temperature.
Ford carburetors should be set up for these fittings. Edelbrocks are easily modified as described above. I suspect a Holley could have the bowl vents drilled on top and have fittings installed, but I am not sure on this.
These parts are all available new, or easily fabricated (the Vacuum Restrictor comes to mind). You'd be better off surfing a junkyard at first, as the charcoal canister can be pricey, as is the control valve. The 79 Bronco has the, in my opinion, most useful control valve. I paid $20 for this stuff at the local junkyard, and grabbed everything. I had the vacuum hose and metal tube here to modify the carburetor for the bowl vent already, so my cost was $20.You'll need a sealed gas cap from a later vehcile, as well for this setup. Without it, the tank would vent to the atmosphere, and this mod would be useless.
I wouldn't hesitate to this to any car that sees regular street use, as it costs no engine power, and maybe 5-10 pounds in weight, total. You may even see a slight gain in MPG, as fuel vapors normally vented from the gas tank would now be trapped in here, until accessed. It was priceless for the fact I can park at work and not get made fun of for smelling like 87 octane.
Next up... fixing my glass fuel filter which I know is awful.
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78 XR7 Stroked 523" C6 3.55:1
79 F100 460 C6 3.55:1

Last edited by FATNFAST; 05-28-2008 at 11:12 AM.
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post #2 of 7 (permalink) Old 05-30-2008, 10:46 PM
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Re: Charcoal Canister hookup for your car (Cure that gas stink!)

Excellent writeup!

408W, 10.x through the mufflers
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post #3 of 7 (permalink) Old 07-12-2008, 08:08 AM Thread Starter
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Re: Charcoal Canister hookup for your car (Cure that gas stink!)

Just a followup.. Been driving the truck daily in 85 degree + weather. Smell is GREATLY reduced. Now all you smell is 'heat' off the engine/headers.

Mission accomplished.

78 XR7 Stroked 523" C6 3.55:1
79 F100 460 C6 3.55:1
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post #4 of 7 (permalink) Old 01-07-2009, 12:31 PM
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Re: Charcoal Canister hookup for your car (Cure that gas stink!)

My '73 Gran Torino has a canister in the space betweenmy fender well and block on the passenger side. I'll get pics if possible. Is this a charcoal canister?
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post #5 of 7 (permalink) Old 01-09-2009, 06:03 AM
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Re: Charcoal Canister hookup for your car (Cure that gas stink!)

Is it a round blue can with steel lines running back to the gas tank and a flex hose running up to the pie pan? If so then yes.
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post #6 of 7 (permalink) Old 01-09-2009, 06:24 AM
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Thumbs up Re: Charcoal Canister hookup for your car (Cure that gas stink!)


And I am glad that some are beginning to see the value of emission control systems as most just trash them with no forethought.

There should also be a vapor return line from the air cleaner housing to the cannister. You might remember them as being the paper foiled black hoses.

The HOLLEY 4180 Series has the bowl vent tubes if interested.
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post #7 of 7 (permalink) Old 01-09-2009, 07:06 AM
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Re: Charcoal Canister hookup for your car (Cure that gas stink!)

That's awesome! I will incorporate something akin to this if I ever have this issue. Maybe on my 67 Effie!
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