TOPIC:

I need some help with these carbs I just got. I went through the carbs and they are very clean inside and out. So last night I installed the carbs and all four cabs started overflowing out of the pod air filters. I removed and adjusted the floats to shut off sooner and they still leak. I repeated this process about four times and the carbs still leak. The tips on the needle valves all seem to clean and smooth. One thing I did notice is the needle valve seats are not tapered. Should they be tapered for better seating for fuel shut off? Is there any other adjustment or something i'm overlooking on these carbs?

tom

Flip the carbs upside down and blow some laquer thinner through the float needle on each, gently, using mouth and plastic tubing. If you're worried about accidently swallowing the stuff, use some whiskey . There should be no flow until you lift the float up. This will give you a good indication of float level at which fuel starts to flow.

If you get flow with the weight of the float against the needle, then the needle-seat is not sealing. Also check for flow AROUND the valve. You may be getting a good seal with needle and seat and leaking around the valve.

Of course if your floats are not floating, they are ot gonna shut off the fuel

Just some thoughts until the true gurus arrive, but realizing you may know more about 29's than me.

Are the float seat needle base gaskets in place?

Are floats properly installed and move freely without hanging up?

Has actual float level been verified via the clear plastic tube method?

Heard somewhere that a drop of light oil to the float needle/base area aids initial movement when freshly cleaned carbs are first put back into service.

Have had occasional success by tapping on the float bowl with a plastic hammer to loosen a sticky float.

Strange that all four would be simultaneously overflowing. And please forgive me for asking this one (because I don't know if it's possible on 29's), but were the floats per chance installed upside down?

Duck wrote:

Flip the carbs upside down and blow some laquer thinner through the float needle on each, gently, using mouth and plastic tubing. If you're worried about accidently swallowing the stuff, use some whiskey . There should be no flow until you lift the float up. This will give you a good indication of float level at which fuel starts to flow.

If you get flow with the weight of the float against the needle, then the needle-seat is not sealing. Also check for flow AROUND the valve. You may be getting a good seal with needle and seat and leaking around the valve.

Of course if your floats are not floating, they are ot gonna shut off the fuel

if you use enough whiskey, you won't care about the carbs...

VM29's have filter screens on the needle valve to prevent debris from entering the needle valve and bowl. You may not have the correct needle valve seat if it doesn't have a filter screen. BTW, VM29's will overflow through the venturi because they don't have overflow tubes.

Ron

I'm still stumped on this one but I won't give up. I'll do more testing in the morning. Thanks for the suggestions so far. I've gone to the Sudco website everything appears to be in place but the only thing I can't tell is if the needle seat should be tapered or if the point on the needle valve should be rubber? The thing that baffles me is when I turn the carbs up side down and try to blow through them the floats seem to be shutting off the flow as they should but right side up they leak. I'm sure there is something I'm overlooking.

What do the floats look like? What float height did you set? The float seats are essentially flat and has already been noted, require installation of the filter on the inside end to avoid crud from getting between the needle and seat since overflow means overflow out the needle jet. Last, did you replace the orings on the seats? Gas can leak past directly and the needle/seat will have not effect if the gas isn't coming from the inside hole in the seat but from around its side...

I think i'm missing the orings. I do not have any orings between the seats and the needle jets.

You should be able to bench test the seats.take the bowls off hold carbs over sink,attatch a funel to fuel line and water. play with the floats raising each gently to see if the seats stop the flow of water.if you cant get them to seal then the seats are bad or you are missing a part.(cant remember what is in those ones)You may be able to soak the ruber seals in oil to help soften them?

www.sudco.com/cat32/31-32.pdf
look hear for parts diagram

There is no oring between needle and seat... the oring I referred to is the one that goes on the outside of the seat and keeps gas from leaking past the OUTSIDE of the seat where it is pressed-fit into the seat well. Sorry for any confusion.