hey got a question. my 78 has a stong exhaust\gas smell when driven. now the car has a small exhaust leak but nothing that should leave the smell on occupants like it does. the carb is a new quadra jet
installed by the a reputable mechanic but i wonder if its running rich. any thoughts.

 The NEW part has me concerned.  Sounds rich to me.

Pull a plug and take a look after a long ride at cruissing speed. Black plugs=rich condition...  (keep yer winders open    )

Check ALL of the hoses going into/out of the fuel tank. Also, look for signs of fuel leakage running down from the top to bottom of the tank, especially at the rear. If the seal between the sender unit and the tank is old, dried up, and cracked, it will give you a very strong fuel odor inside the cabin.
If you are getting that strong of a fuel smell inside the car, you have raw fuel leaking somewhere, either from the carb, or the fuel tank/hoses.
Look around the fuel pump with the engine running, too...it could be leaking, but you wouldn't see much evidence of it just sitting, as the fuel would evaporate too quickly to leave a puddle.

ok fuel lines to the pump seem ok. but the lines going out of the canister are not right one may be missing can the line thats missing be capped? any ideas on where to find a fuel canister schematic so i can see where the lines are supposed to go. i have a haynes but they seem to be crappier latley with very little details. scrappy782010-11-06 06:43:58

Well looks like you found the problem..without the carb being hooked up to the canister all the fumes from the tank are ending up venting under the hood..I know evap stuff people think rob the car of power but if it still setup to have it, it should be hooked up..you can plug the canister stuff and get a vented cap..that's how mine works so it is not a big deal..I don't think the emissions police are in your part of town!
Rich

ok would a generic gas cap work or does it have to be something special

If you buy the stock replacement it won't be vented..get a vented style..maybe Joel has a better idea on this also.
Rich

ok thnx 

Why not just return the canister to being operational? Without it working your garage will also fill with fumes from the vented cap and the carb vent.
I replaced the canister and hoses on my 82 in about 40 minutes. By removing the side vent the access to the hoses and canister is easier.
There should be a vacuum schematic in the GM service manual.