Quadrajet with no charcoal canister vent...

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MrSony

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Nov 15, 2014
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How old is that carb? They used to have a vent on the top of the air horn with a spring loaded rubber disc. At rest it closed the hole and at any throttle opening it opened. The hole was closed up approaching emissions carbs but you still saw the castings for the spring and plug mechanism. I forget what year it happened but the vent tube was added to the carb, the tank had a non-vented gas cap, and the charcoal canister appeared.
It's a '77 M4MC (the one I'm looking at, mine is a '78, potential carb is a 17057241, mine is a 17058241). Only difference is air horn is slighty different (has the triangle shape instead of the little nipple up front on the air horn). The '77 has the boss still for the vent tube, but just didn't get it I guess for the A bodies. Maybe they vented a different way with check valves, thermal switches, and other BS that doesn't make sense...

I guess it was '78 with the downsized A body that they added the vent on there. At least for Buicks. If the boss is there, I'm sure the passage is there.

Edit: don't know if i mentioned, but the potential carb is from everyday performance. he has added the tube, so i assume the passage is there. lol.
 
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MrSony

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Nov 15, 2014
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I have used quadrajets with no bowl vent tube and they did not smell like gas. Even with the vent tube the bowl is still open to the atmosphere with this tube...

View attachment 92348
... the one thats normally covered by a sealed filter/housing?
 

MrSony

Geezer
Nov 15, 2014
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I would think you may have some other issue, maybe a bad line or the canister itself has a crack. The system should be drawing in air via the canister as fuel is used. I've done this to several cars over the years and never had that issue. On one car, i capped the canister and actually built up a vacuum in the tank to the point that when i went to gas up, the tank poped out with a loud noise. The other way you could go is to plug the canister and get a vented gas cap like older cars had or modify the one you have.
i didnt say mine smells like gas. it did, until i put the charcoal canister in off a junkyard car with 43k miles. Shame. but the car was cut in half, so f*ck it. how my car was for 2 years was was the stock non vented cap, and the exposed bowl vent plugged (again, '78 m4mc) and vent line plugged. always smelled like gas. no nozzle drip, sipped gas, no leaks, no wet spots, no mysterious gas loss, nothing. just the smell. hot, cold, whevever. put the canister on, no smell. still no smell 1 year later. until i take the air filter or vent line off.
 

Canon_Mutant

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Aug 15, 2015
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Yeah, and I was implying leaving something unhooked on the canister itself => gas smell. When I moved PS to DS, I had to slide all the hoses under the gas line and I thought I must have nicked something on the gas line or knocked something loose. Nope. Just that yet to be hooked "back up" canister setting over there. The gas smell was bad enough I was expecting a puddle under the car or in on top of the intake. Nope just the canister. I was surprised especially as long as it has been sitting it would still be that bad. But, one of my many yorglemeyers along the way was not draining my tank. With the frame loose for the bushing swap, I'll be running all new lines as just another in the long list of unplanned changes so I'll drop the tank and do things right one of these days . . . :confused:
 

RegalBegal

G-Body Guru
Jul 10, 2009
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i didnt say mine smells like gas. it did, until i put the charcoal canister in off a junkyard car with 43k miles. Shame. but the car was cut in half, so f*ck it. how my car was for 2 years was was the stock non vented cap, and the exposed bowl vent plugged (again, '78 m4mc) and vent line plugged. always smelled like gas. no nozzle drip, sipped gas, no leaks, no wet spots, no mysterious gas loss, nothing. just the smell. hot, cold, whevever. put the canister on, no smell. still no smell 1 year later. until i take the air filter or vent line off.
Gotcha brother. ;)
 

pontiacgp

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Mar 31, 2006
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Kitchener, Ontario
i didnt say mine smells like gas. it did, until i put the charcoal canister in off a junkyard car with 43k miles. Shame. but the car was cut in half, so f*ck it. how my car was for 2 years was was the stock non vented cap, and the exposed bowl vent plugged (again, '78 m4mc) and vent line plugged. always smelled like gas. no nozzle drip, sipped gas, no leaks, no wet spots, no mysterious gas loss, nothing. just the smell. hot, cold, whevever. put the canister on, no smell. still no smell 1 year later. until i take the air filter or vent line off.

what cars were you refering to that smelt like gas?
 

MrSony

Geezer
Nov 15, 2014
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Des Moines, Iowa
what cars were you refering to that smelt like gas?
50s, 60s, 70s until smog stuff started getting heavy handed. and i guess the same could be said about a car with a terrible tune.
 

MrSony

Geezer
Nov 15, 2014
6,793
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Des Moines, Iowa
Gotcha brother. ;)
purpose of the canister is to trap fuel vapors. yknow what fuel vapors smell like? fuel. without it on a fuel system designed to have it, it will smell like gas. i put the canister n my car, no gas smell and no more gas tank hissing at me when i pop the cap off.
 

pontiacgp

blank
Mar 31, 2006
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Kitchener, Ontario
50s, 60s, 70s until smog stuff started getting heavy handed. and i guess the same could be said about a car with a terrible tune.

I was born early 50's and I can tell you that none the cars that my father, my uncles and aunts, my grandparents bought and every other car I was in ever smelled like gas.
 
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