bucksy99

so for the first time I took the carb out and rebuilt it. Even though I have only novice skills I think I did a relatively good job cleaning it up and putting everything back into place. After I started the engine fuel is squirting out of the pump hole on the carb. Quite a lot actually. Does that mean the float is stuck or could it be something else.

Thanks for any suggestions.

SmokinBBC

Assuming it's a qjet, float level too high. needle not seating proplerly, stuck float, needle on float arm incorrectly, etc.

7T1vette

Assuming that you installed all the parts and in their correct locations, it's most likely that you installed the needle valve retainer wire [hook] in one of the holes on the float arm. That is a 'no-no' as it can bind up the valve and keep that valve system from working properly. The hook should just be place over the center part of that arm...so that the valve will always work freely. Many rebuilder just throw the "hook wire" away.

(There are lots of other possibilities, but that one comes to mind.)

bucksy99

Thanks
will the wire stay on there that way?

Sorry forgot the details. It is a M4MC Rochester Quad in a 75'

Tim H

Yes, there is no where for the needle to go but up and down once its put back together.

bucksy99

thanks, just wondering if the hook would slip off the float arm after a while.

Also while we are at it; what is opening the secondary air flaps ? just air pressure/flow ? I know the primary choke closes it, but what opens it?

Thanks

7T1vette

The hook will not slip off the float bar after assembly. The [upper] air valve is opened only by the incoming air flow. There are secondary "prevention" devices that keep the throttle plates and/or the air valve from opening, but once those details are satisfied, then airflow is the only force working to open them.

There is a spring which winds up as the air valve is opened; it determines the rate of opening. This upper air valve system is what sets the Q-jet apart from all the other carbs. It provides a "demand" type system which is self-regulating. Thus, a BIG cfm carb (750-800 cfm) can be placed on a hi-performance BB or on a 'base' engine SB by changing only the rods and jets.

Good luck on solving your flooding issue.

Mashman

It will stay on, that little bump where it's connected will keep it on.

As mentioned earlier, many people simply don't use the clip at all (Lars has even mentioned not using it if you have a problem with fuel bowl draining after shutdown). The fuel pump will provide enough pressure to push fuel past the needle when the float is lowered.

bucksy99

forgive my ignorance, but isn't the the purpose of the float to restrict the fuel flow? The float rises with the fuel level in the bowl which lowers the needle an restricts the amount of fuel that goes into the bowl.

MelWff

that is correct but the tang on the float as it goes up will push against the top of the needle with or without the clip and will permit the needle to rise as the float drops.

bucksy99

Got it. When the float is stuck it keeps the needle up even with a filled bowl. Thanks everybody. I will put it back together and try again.

scottyp99

The float and the needle and seat in a Q-jet work alot like the flush mechanism in the back of your toilet. Flush the toilet (step on the gas) the water level goes down (fuel level in bowl goes down) as the float goes down, it turns on a valve to let more water in (as float goes down, opens needle and seat, letting fuel in) when the rising float reaches a certain level, it shuts water valve off (float rises and closes needle and seat). So, if you want to get a good visualization of how your float works on your Q-jet, take the cover off of the back of your toilet, give it a flush, and watch how it works. Holleys are different, the needle sits on top of the arm connecting the float to it's fulcrum, so as the float goes up, so does the needle.


Scott

bucksy99

got it all back together and there is still fuel coming out the opening of the pump shaft. It seems to be not as much as the first time but still it's coming. I am very sure that the new float and needle are working fine. Is there anything I am missing here?

thanks
Norman

Mashman

There are only a couple of things I can think of.

A problem with the float, it's set to high, or it's binding, or sinking. Did you replace the float when you rebuilt it? If you didn't before, you want to make sure to replace the float with a brass float.

Are you using a mechanical fuel pump, or an electric one? If electric, was there a regulator somewhere that maybe didn't get put back on. An electric fuel pump will provide to much pressure, and will push fuel past the needle, that's why a regulator is needed to use one with a carb.

scottyp99

Well, the needle and seat, or the float level are about the only things that would cause this, so if you are REALLY sure that the needle, seat, and float are just fine, then it must be evil spirits or something.


Scott