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Another Carb Question

Gray035

Full Member
Joined
Apr 16, 2012
Messages
187
Loc.
Encinitas, CA
So I have a 2100 two barrel on a 289, and I just discovered that it's leaking fuel out of the base of the carb. As far as I can tell it's coming through the gasket where the carb spacer meets the stock manifold. I just replaced that gasket, so I am surprised. I can't see any leaking from anywhere else on the carb. Any ideas about what the problem is? Do I need a thicker gasket? Could the spacer be warped?
 

Deano

Bronco Guru
Joined
Jan 9, 2010
Messages
1,182
Do you have a gasket like this under it
nudaneta.jpg
if so it may not be seated flush on it. I always get a new one for mine and don't seam to have any problems. I have ran into problems of not getting all the screws tight on
du6ate7y.jpg
bottom side plate. I have got in a hurry a few times and left a gasket out to. Just my $.02
 
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Gray035

Gray035

Full Member
Joined
Apr 16, 2012
Messages
187
Loc.
Encinitas, CA
I looked under the carb with a mirror and it doesn't look like its leaking from the carb itself but from the gasket between the carb spacer and the manifold. I put a new gasket in when I put the carb back on bit it is now soaked with fuel. I'm wondering if maybe a thicker gasket would fix the problem, if such a thing exists. Or I guess I could double them up under there. The last resort I can think of would be to find some sealant to put on the gasket (although I'm pretty sure RTV isn't compatible with gasoline). I'm sort of at a loss...
 

Deano

Bronco Guru
Joined
Jan 9, 2010
Messages
1,182
The question is why is the gasket getting soaked with gas. Is the float sticking and not shutting off the gas to the carb, is it hard to start, flooding out, when you shut it off can you look down in it and see if the gas is dribbling or dripping and soaking the gasket or is it just in one spot on the gasket or the hole gasket is wet. Then it can be figured out what may be the problem.
 
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Gray035

Gray035

Full Member
Joined
Apr 16, 2012
Messages
187
Loc.
Encinitas, CA
I just rebuilt it so it has a new needle valve. I adjusted the float according to the directions. 7/16" from the top of the carb measured at the end of the float away from the needle valve while holding the valve lightly closed. Not only is it leaky it's running like crap. Almost like there's a vacuum leak but I can't find one. I sprayed ether all around the base and the vacuum hoses and no change to the idle. Also the right idle screw can be screwed all the way in or all the way out and makes no change to the idle. The left one makes will make the already poor idle worse if it is screwed in too far. But no matter how far I let it out the idle never gets to where it should be. I did notice while I was tuning it that vapor was coming out the vents of the float bowl and getting sucked down the top of the carb. That could be the cold weather (for San diego) I guess.


Other fun facts: The motor is timed at about 10 degrees btdc and the dwell is 26 or so. It was running pretty well before I changed out this carb. I'm thinking of putting the old one back on to see if that one makes it run like it did.
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Even new needle seats can be bad. But it could just be a piece of debris in the needle seat.
Could be a internal vacuum leak but that doesnt cause the gasket to be wet. But will cause the idle issues. or it could just be a dirty idle air bleed passage.
 

Rustytruck

Bronco Guru
Joined
Feb 24, 2002
Messages
10,875
I would be looking at the chambers outside the carb body. I.E. the powervalve and gaskit under the carb, the accelerator pump on the front leaking or the red rubber plug inside leaking. The bronco 2 barrel will run with the top off so checking actual float level running is possible just dangerious for fire.
 
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Gray035

Gray035

Full Member
Joined
Apr 16, 2012
Messages
187
Loc.
Encinitas, CA
Update: I took the carb off and stripped it all down (again). Blew out all the passages with air. Then I doubled up the gaskets on both sides of the spacer. Put it all back together and it's made a big difference. I still have some fine tuning to do but at least now it's drive able.
 
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