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gas exaust smell

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    Posted: Apr/16/2018 at 12:38am
I need some help if you all please , I have a 401 1968 AMX with 727 trany ,runs very well but after I shut it down after a trip and park it in the garage it has a bad smell of gas ,I am running a 600 cfm Edelbrock carb ,,I have tried running a Holly 750 vac secondary and the same thing ,on a open trip the pipes are brown ,I have tried retard, Advancing and dead on for timing ,I have 5  lbs of fuel pressure at the carb , the jets are stock , could the floats be off or too much jet size  ?????? 
1968 AMX 401/727
1984 Eagle 4.0 org owner
1988 Eagle (time machine)
1980 Jeep J10
1977 Hornet AMX (Green)(sold)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mixed up Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 12:53am
with a holly carbs you might want to play with the jetting on it there always fat and check the flout level I set them so if you bump the car side to side it just trickles out
69 amx 290 auto
65 220 290 4spd
80 ford fairmont
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 12:57am
What Fuel Pump?  Ya'know... a YouTube Guy does carbs with videos...
He shows / claims with modern gas gotta do like 3.5 ? or so psi !...
Yah... I know... but... vapor pressure... volatility... ethanol blend...
Ya know... the lower PSI Fuel Pressure... maybe somethin' to it...
Then the OBVIOUS question... what Intake Manifold...
And... is the Choke Stove Heat Crossover Blocked !?....
Any Carb Spacer?  Phenolic or otherwise?  Boiling Carb?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Boris Badanov Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 6:31am
As mentioned above, a boiling carb after shut down.

Are you using an aluminum intake manifold?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote mmaher94087 Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 11:53am
"..1968 AMX ..". Original gas tank? They sometimes rust out on the top.
Mike
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ditdit Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 6:36pm
I am running a stock case iron intake , the exaust cross over is not blocked , the gas tank was treated about 10 years ago , I am running unleaded gas  and have tried regular ,middle and super blends , the vent on the gas tank is not blocked ,I am not running a spacer on the carb  , but I don't know if the fuel is boiling ,I will have to check it out    thanks guys
1968 AMX 401/727
1984 Eagle 4.0 org owner
1988 Eagle (time machine)
1980 Jeep J10
1977 Hornet AMX (Green)(sold)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PHAT69AMX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 7:25pm
Like the other thread about a 287 carby, the fumes you're smelling may be due to modern gasoline.
Fumes can also come from the correctly working vented gas tank.
Would imagine you've already checked it all over for no leaks.
If a stock type mechanical fuel pump, the diaphragm can age, allow fuel into the crankcase & oil,
or maybe even vent fumes out a small fuel pump casting "vent hole" above the diaphragm cavity.
Way Edelbrock Carbs are made, usually don't "drain themselves" after shutdown into the intake manifold.
Oh, is the Eddy Carb a Manual Chock Model or an Electric Choke Model ?
If the Needle Valves are "iffy" they could overfill the bowls after shutdown causing fumes.
If / ounce Bowls overfill causing fuel to flow out venturis, guess it could drain bowls by siphon action.
Or just today's "modern gas" is just boiling off more easily, maybe causing floats to drop.
Exhaust Heat Riser Valve still in place on passenger side exhaust manifold outlet?
If the fuel odor is a new occurrence, would image either a leak somewhere, or a boiling carb...

Your original question(s):
(revised) Jetting, if too rich, could cause gas smell once off and parked, unburned fuel in exhaust...
Incorrect Float Setting in either type of Carb could, yes.
Unsure about brown pipes, mine were always a nice pale gray when running the best.
Guess if it is too rich and/or has weak spark, unburned fuel could "collect" in the exhaust...
It won't burn there because it has no oxygen to use.
Pull the coil wire off the cap, place it near metal, and crank it over, it should SNAP, be white-blue.
If the spark makes no noise and/or is yellow or orange, it is a weak spark imho.
Also once sparkplugs get Fuel Fowled from any reason they are no good anymore they say....

Ah, and yes, I agree with what Greyhound is talking about in the next post as a possibility also...


Edited by PHAT69AMX - Apr/16/2018 at 10:08pm
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Greyhounds_AMX Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 7:47pm
How close are your tailpipes to your gas tank?
Chris ("Mojo")
1968 AMX 390
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ditdit Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 7:53pm
I did notice a few months ago after I let it sit for 4 or 5 days and tried to start it there was little fuel in the carb so I had to crank the engine longer till the fuel come up to the carb, there is no heat riser ,I do have a old mechanical fuel pump it is not leaking on the outside I have checked the oil for gas smell and it is ok. the smell is comming from the exaust pipes ,both of them
1968 AMX 401/727
1984 Eagle 4.0 org owner
1988 Eagle (time machine)
1980 Jeep J10
1977 Hornet AMX (Green)(sold)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote ditdit Quote  Post ReplyReply Direct Link To This Post Posted: Apr/16/2018 at 8:00pm
i forgot to answer one question ,the exaust pipes are all stock the way it was mfg
1968 AMX 401/727
1984 Eagle 4.0 org owner
1988 Eagle (time machine)
1980 Jeep J10
1977 Hornet AMX (Green)(sold)
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