1 brl carb needle valve sticking

[mare68]

The needle valve in my 1 brl continues to stick and the bowl constantly runs dry.

I've cleaned it examined it and it looks fine. It just stays up against the seat when I take off the top of the carb. It should just fall from gravity.

Will a very small deformation of the rubber tip cause this? or is the float off its correct height setting? The brass seat looks fine, no burrs or other defects.

I can't see anything physically wrong. All the parts look fairly new. I've had the car on the road for about 3 weeks and i've been fiddling with this since then.

Everything else seems ok, fuel pump is delivering, accelerator pump works when the bowl is full.

I could get a rebuild kit but if it's something else I'm missing, I'm still at the same place.

Any hints?

 

[fb71]

the tips of the needles get "necked" after a period of time, and start hanging up. This "necking" is only maybe 0.001", but its enough to bind the needle in the seat. Pick up a rebuild kit and just replace the needle and seat, check your float afterwards, and keep on rockin'!

 

[mustang6]

When you take the top off the carb two things should happen.

1) the float should drop down freely to it's maximum range of travel. Make sure it does this and that the little flange or spot on the float that closes the needle valve moves enough and creates enough of a gap that if the needle valve was operating freely it would lower down and open up.

2) The needle valve itself should drop down a bit when the float no longer is pushing up against it, but if it does stick slightly and drop down if you nudge it just a little bit then I think it's OK. Remember there are a few psi of fuel pressure that are also trying to push that valve open when your engine is running so if the float isn't holding it closed then it should be pushed open. If the needle valve is sticking pretty hard then it should be replaced. They can form a ridge in the rubber tip or get gummy on the tip and stick fairly well on their own if they are old. Usually the symptom you see first with a worn needle valve though is flooding of the carb, when the tip gets deformed it usually doesn't seal well.

Based on my experiences with issues like you are having, I would bet your float is not moving freely. This is commonly caused by the float binding on the shaft that holds it in place. It can be kind of tricky to get the shaft put in right- it has to rotate freely in loops in the float it rides in as well as the slot in the carb top itself.

Check those things and I think you'll find your answer. If all those items check out I would pursue possible fuel delivery problems with the pump or blockages in the lines from the tank to the carb. It may be running dry because of fuel starvation.