The Camaro Club (UK)

Ok.

Few questions coming up...

The standard setup for carb'd cars usually a fuel line out of the tank up to the carb and then a fuel vapour line that runs from the tank to a charcoal canister and into the carb (i think).

I guess the reason is that as the volume of fuel goes down, the lost volume has to be replaced by something... air. It get's this through the vapour line via the charcoal canister. I think?

Now, i have an Edlebrock carb and intake. The vapour canister was removed and the vapour line was cut at around the brake master clyinder. The tube was also rotted away in many places.

Trying to figure out what to do. I cut the pipe off where it was still good (just as it comes out the tank) and put a rubber hose and bung in there. This may of course cause pressure issues.

2 options i have so far:
1) Fit a vented fuel cap. The issue i see here is that it means that if air can get in, fuel vapour can get out. So it could smell and probably don't want that in an enclosed garage.
2) take out the bung and replace it with a breather filter, like you get on a crank case. I'm thinking this is the better option? Trying to avoid the vapour smell issue and running a line into the engine bay etc. I've had a crankcase filter before in a car that had an induction kit put on but it didn't do a lot of filtering so the car always smelled of oil. Something like this maybe?
http://www.ebay.co.uk/itm/New-Breather- ... 3f096c5468

Anything else i'm missing?

Ideally would run the vapour line to an inlet on the carb so that the car ran on a mixture of fumes as well as fuel (don't tell the government, we could get silenced though, doubt you would get enough vapours to make a big difference, but you'd still see an improvement on MPG's). Would need some check devices in place to avoid backfire, so kind of like an LPG setup.

Or, could do something a little more complex... take the AIR pump from the Trans AM that got taken off, hook it up to a pulley and take the output to the fuel vapour line, therefore creating a positive pressure and not allowing the vapour to leave the tank. The AIR pump only produces a few PSI and you could put in a check valve near the pump end so that it doesn't go over say 2 PSI. Then, you would always have air replacing the volume of fuel that leaves the tank.
Anyway, back to the options, crankcase filter would do the job? Or have i misunderstood the system.

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It's an emission control device.
When the your car is parked and the temperature rises you start getting petrol vapour from the carb float bowl and the petrol tank, these vapours are allowed to go into the charcoal canister where the activated charcoal (same stuff that's in gas masks) absorbs it.
When the engine has started a purge valve opens and slowly allows these 'strored' vapours into the intake manifold for burning.
If you remove the canister and plug the port on the carb it will not affect the running and a regular pressure/vacuum vented fuel cap will be just fine

Thanks for the explanation and diagram Neil!

So by the looks of it on the diagram, the float already has a vent that goes into the air intake portion of the carb, so that way any fumes get sucked into the combustion chamber and burned.

I'm looking at the Edelbrock manual and can't seem to see a port for getting the float vapour out, so leads me to think it's internally routed.

As for the fuel tank, i have a non vented cap, will it still be ok to keep this and have the fuel tank vapour line plugged up? I'm just trying to work out what will happen as the fuel level goes down, or i guess the fuel cap isn't completely sealed, so some air would get through?


Cheers!

_________________
How to post pics: When writing a message, scroll down and use the "attach file" option. Where possible, a photo sharing service can be used such as Flickr, Imgur etc. The image location (usually ending in .jpg) can be copy and pasted between the ][ brackets that appear when you click the 'Img' button (you can find this button at the top of the message box).

How to post youtube vids: Click on the 'youtubeHD' button at the top of the message box and in the middle of the ][ brackets that just appeared, copy and paste everything from the youtube web address that appears after the = sign i.e if this is the url: https://www.youtube.com/watch?v=K2cNqaPSHv0 just copy "K2cNqaPSHv0").