Road Runner Nest

A redesign of the fuel tank vapor separator went to the production line around April 72’. Sounds like you have the earlier 71’ style design having a larger vapor/expansion tank mounted inside the left rear wheel well and a fuel tank with vent line nipples on the driver’s side. The later design used a smaller separator mounted to the shock cross-member directly ahead/forward of the tank and used a fuel tank with nipples exiting the front. Both systems had a hard vent line running forward to the engine compartment mounted charcoal canister.
Here’s a shot of the later 72’ separator.

Regarding the evaporative control system.

Anybody have any idea about the specifications for the activated charcoal in the emission cannister on the fender well? I have searched the web and found a lot of different varieties and sizes, but don't have a clue as to what to use? Most sources are from aquarium supply places, but is that the same as in an automotive application? Or is activated charcoal the same, no matter where it's used?

Enquiring minds and all that!

What is in the rear fender well is just a vapor separator. No charcoal.

Charcoal canister was added in 72 up front next to the radiator.

471Magnum wrote:What is in the rear fender well is just a vapor separator. No charcoal.

Charcoal canister was added in 72 up front next to the radiator.

Guess I didn't 'splain well enough. My car doesn't have the big vapor separator in the wheel well, but instead has the small one just in front of the gas tank, which has the vapor tubes that come out of the tank on the front.

I am speaking of the charcoal cannister in the '72, i.e. this one:

Sounds like you are considering cutting open your canister and replacing the charcoal? Activated charcoal is activated charcoal, used differently to filter aquarium water and likely crushed finer than would be necessary for automotive purposes. When used as part of a filtration system the charcoal will eventually become saturated and require replacement but when used to temporally absorb and store fuel vapors, unless becoming contaminated with oil and or dirt, should continue to serve its purpose indefinitely.
One thing I have found with the 72' four line two stage purge canister like yours is that with age the diaphragm the controls the secondary metering by-pass will develop pin holes and leak. Causing a higher rate of purge at idle(vacuum leak). A quick vacuum test on the diaphragm nipple will verify the correct function. Make sure to replace the filter on the bottom of the canister periodically.

I have a spare wheel-well vapor can. If you're interested, PM me or e-mail at quapman@aol.com for price, pics, blah blah blah.

72RoadRunnerGTX wrote:Sounds like you are considering cutting open your canister and replacing the charcoal? (edited for brevity)

No need to cut open the cannister. Depending on the size of the activated charcoal I can just put it through the bottom of the cannister then put the fiberglass filter/bottom on it to keep in in place. If the "new" activated charcoal is small enough it will fall through the grate on the bottom of the canister and fill it up as the original charcoal did.

My issue is, what "kind" of activated charcoal can I use?

I hope you don't mind me using this thread to ask a quick question:

Anyone know of any issue with putting a '71 gas tank into a '72? I can't think of any off hand as the extra ports used in the evap system could just be plugged off.

Thanks

71 tanks are the same as early 72 tanks.

There are no extra ports. The location of the ports is different.

Is this vap cannister really necessary, can it just be blocked off >?
Im just curious because mine has been striiped of it and wondering if its somthing thats really necessary.

471Magnum wrote:71 tanks are the same as early 72 tanks.

There are no extra ports. The location of the ports is different.

*bangs head on table*

Thanks! I guess that's what I get for not having looked at the car in a few years.

Yes, I would also like to know if the can is really necessary. I'll put mine back for appearance, but I have no idea it it ever worked n the past 10 years!
Thanks