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Charcoal Canister plumbing question


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I recently had all my smog from my 74 removed when i had upgraded the engine added 2 carbs (don't ask why, i regret).  The exhaust smell is super rich, may look into installing cats. 

 

The outlet hose from the fumes tank in the trunk enters at the firewall i connected to charcoal then connected to a screw hole in my air-cleaner?  

 

I don't feel a suction but is it enough to suck fumes from trunk>Canister> Carb?

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1 hour ago, kbmb02 said:

Because the air filter element is open (to the air) in the engine bay, the fumes will escape. -KB

Ken...this is something i'd like to know more about...it's my understanding the charcoal canister worked with gas tank fumes, how did it play into the exhaust fumes... isn't excessive exhaust smell a running to rich problem?

 

sorry for stupid questions

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Sorry Etsy 2 different issues i brought up.  

 

One being exhaust is overwhelming.  

 

second how do i vent the expansion charcoal tank in the trunk.   I am hearing if not vented then trunk will always stink like raw gas fumes,  which it does now. 

 

Thank you Ken, but with this set up will i vent the rear smell to the front? 

Edited by oldskoul
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The charcoal cannister holds the gas fumes from the vapor tank (in the trunk), until there is manifold vacuum to suck it into the intake. This has nothing to do with your exhaust gas smell. What you are smelling is unburned hydrocarbons (raw gas) which means your engine is too rich. Adding a cat converter will be a huge waste of money/time/effort. It will be destroyed on short order by the rich mixture. This is why cats are only effective on fuel injected engines, capable of keeping the F/A ratio in a very narrow range

(~14.5 to 14.7). This tight control required an O2 sensor and computer to provide a feedback control system for fuel and spark.

 

Here's the sketch of the charcoal cannister connection.  Hope it helps with your project.

 

Evaporative System.jpg

 

 

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   As I recall, any gas smell in the trunk would indicate a leak/seepage somewhere back there. Most common areas would be a cracked gas rubber filler neck boot or loose clamps. Seepage from sending unit rubber seal and electrical connector, especially when tank is full. Plastic pipes can get brittle/kinked and should have the rubber sleeves on them at body mounting points. The old fabric cover style of hoses attached deteriorate/loosen and leak eventually. The plastic vent tube from filler neck to expansion/recovery tank in trunk should be connected to bottom fitting. Hose to front charcoal canister from recovery tank is connected to top fitting. Connect up wrong and liquid fuel gets pushed/sucked into charcoal tank on a hot day or if tank is overfilled and you'll notice a nice puddle under the front of your car. Also, check the plastic expansion tank where it slides into its bracket. I've very carefully pressure tested them in water to check for leaks. The plastic has been known to crack and leak (just like the washer bottles). Due to its limitations, charcoal canister up front can only absorb so much vapor and then you will smell it. Diagram from John76 shows it all. By the way, is that hose to the charcoal canister and carbs from H/Depot? Hope its fuel resistant and thick enough to not collapse under suction. 

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The air cleaner is from timjasonperformance.com he's got necks on them now which i think is a good idea. 

45's and not sure which linkage. 

i don't see any vacuum hoses post engine upgrade. 

 

Anyone know a super-excellent carb guy near west LA.   My mechanic had  "synchronized" but my mechanic says the richness is what it is.   I don't believe him.  

 

 

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Edited by oldskoul
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I would suggest ditching the whole vapor recovery system, there isn't really a good way to hook it up to dual Dcoe's. Remove the canister under the hood and the box in trunk and connect the tank vent to the little hose on the filler neck. For the valve cover hose either put a small filter on it or get an oil catch can.

 

Also if you haven't already replace all rubber fuel lines and used the metal return fuel line instead of the factory plastic fuel line that goes through the passenger compartment, I would strongly suggest you do that.

 

As for the running rich, you should check the jetting in your carbs and get someone who knows Weber Dcoe's to tune them. If your engine is stock those 45s are really too big, typically 45s are more for racing and 40s are more for street.

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