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1967 Mustang restore - carb is spouting gas

Earlier this year, I began to restore my '67 Mustang. It’s been garaged for 14 years, unfortuanately, not properly prepared for a long sleep. Anyway, in my spare time, I’ve replaced the gas tank, cleaned the fuel lines, replaced the fuel pump, distributor & contact points, solenoid, etc… I also took the carb off, rebuilt it from a kit, and put it back on the engine. A few days ago, it was finally time to try and start it. Gas flooded the carb, and shot up through the oriface at the top-from of the carb. I opened the top of the carb, checked the float, checked the needle action, …I’m far from an expert, but it seems to be working properly. With the float riding high, the needle drops into the little cylinder (whatever it’s called), …with the float depressed, the needle raises up. I tried it again. Same thing. Alot of gas shoots up through the top oriface. It’s as if nothing is stopping the gas from entering the carb when there’s enough gas in it. Can someone point me in the right direction about what to do next?



Either the floats are sunk and need replaced or the needle and seat are not sealing, allowing uncontrolled fuel into the float bowl and out the bowl vents.

The float is supposed to rise with the fuel level and push the needle into the seat. Anything that stops the needle from seating will cause the result you’re seeing. If you didn’t replace the needle and seat when you rebuilt the carb you should do it now. Same with the float adjustment, if it’s not done it needs to be done now.

If fuel spits out of the freshly rebuilt carb, your doing it wrong.

The needle valve should push up into the seat as the float rises. When the fuel reachs a certain point, 2/3 up the bowl I believe, the valve should fully seat, and cut the fuel. The rebuild instructions should have had the proper procedure to set the float level. Pull the carb and try again.

Flip the top of the carburetor upside down. The floats should be roughly parallel with the bottom surface of the top. You should have had a gauge and dimensions provided with the carb kit for the distance from the bottom surface of the top and the bottom of the float when its upside down.

You make the adjustment by bending the tang where it contacts the bottom of the needle.

The float level is too high or the float is full of gasoline.

engine size, type of carb???

Sounds like the float needle is not shutting off on the seat. You could try removing the top of the carburetor, invert it, and attempt to blow through the inlet nipple. You should not hear or feel any air hissing through the seat.
If you do, either the needle/seat is flawed or the float adjustment is way off.

Another possible cause could be excessive fuel pump pressure. Excessive pressure can cause the float to sink and caue the problem you have.
This is normally not a problem if you replaced the pump with an original mechanical fuel pump but it’s something to consider anyway.

Yet another possibility could be an old float that is gas-logged. You did not state if the float was also replaced but sometimes old floats will absorb gasoline and sink instead of rise. Hope some of that helps.

If this carburator is a Holly with externally adjustable float level, check that both o’rings are in place and intact on the inlet sleeve (where the float needle valve fits into). If one of these are missing or not sealing, you will get exactly what you describe.

Hope that helps.