help me identify these carbs please

[3ryce]

I need help identifying these carbs. The other day I went to autozone and had ordered a rebuild kit, however after looking at the kit and then looking at the carb and back to the kit, then to the carb, ect. i came to the conclusion that the kit was wrong. The carbs say z therapy on them so im pretty sure these are not the stock ones. There are three screws holding the bowls on but not sure if there called the three screw su carbs. I got the rebuild kit cause this carb in the picture was leaking on the bottom, the screw driver is pointing to where it was leaking fuel. not sure if I need a full rebuild kit but where is a good place to get one? Is there somewhere that kinda shows how to take them apart? I have never done this before and if there is a simple fix to this fuel leak? I dont wanna take to much apart cause I dont have gaskets to replace them.

Edited April 4, 2013 by 3ryce

[Captain_Zeros]

They're stock pre-1973 240Z Hitachi round top carburetors, if the dome is held on by 3 screws they were probably made in 1972 if I remember right. As far as guides on them I can't recommend ztherapy's "Just SUs" video enough. It's pretty long and not high production value, but it's all killer no filler as far as information goes. Barring that, read the carburetor chapter in the factory service manual, they're available for download here: XenonS30

In my experience your main spots you can leak are either having your fuel mix set way too rich or your choke left on so fuel can go over the top of the jet, leak down the jet tube and out the bottom of the carb, OR the flexible rubber hose connecting the jet and the float bowl is deteriorated and leaking fuel. Also if your float bowl valve where the fuel line goes into the carb is stuck open, the fuel pump will pump fuel into them until fuel pukes out everywhere.

[3ryce]

thanks man for the fast reply. It was while I had the choke on, as the car was about to die if i took it off and it was the first start of the day too. cold. Thanks for the link too! Ill try to tap the float bowl and see what happens. But ya the carb kit I got ,GP sorsen, ya not for the carbs I have. The car was kinda warming up and as I pressed the pedal and let it off the car would backfire, then I went to look at the car and noticed the fuel leaking. I hope its related cause that means its a easy fix, if not then idk.

[Bruce Palmer]

Push the choke in and I bet it stops leaking...... Captain_Zeros pretty well nailed it....... This is what I call a major crisis of minor proportions..... nyuck nyuck

[bartsscooterservice]

I did mine, and didn't have any gasket kit... The float bowl is besides the carb, then feeds the fuel through the hose to the nozzle. It could be your float level to high or choke sticking what Captain zero is saying above.

Clean the nozzle very well, so that the choke moves up and down freely. Clean the float bowl to, and the seat where the needle goes in, check the needle tip. I used special sealant for the float bowl, and it's holding fine.

[3ryce]

Is it normal for it to leak with the choke open? If i closed the choke the car would have stopped running. I did take the float out and cleaned it up a little bit. everything seemed to be working in order. Hopefully just by messing with it a little bit i fixed something. I mean the car has been sitting for like 5 to 10 years so ya. So stoked to get this car on the road again, ive replaced many things. Gas tank and fuel lines, alt and fuel pump, manual and electrical, cant the the later to work right now but ya. haha. Thanks for the help guys, ill keep messing with it.

[Bruce Palmer]

What you are doing with the choke on is dropping the top of the nozzle below the static level of the fuel in the float bowl allowing fuel to puddle up on top of the nozzle hence leaking down between the nozzle and the tube.

The engine dying with the choke off is a rich lean situation and can be dealt with by lowering the fuel nozzle..... Just arbitrarily messing with the float level makes me nervous..... but don't feel bad, everybody does it..... then I get to try and unring the bell over the phone....

[bartsscooterservice]

Is it normal for it to leak with the choke open? If i closed the choke the car would have stopped running.

I'd say no. You mean it doesn't keep running when you close the choke? Your float bowl exit might be clogged... or the upper part where the needle goes into the seat.

[Stanley]

It's normal to need to let the car warm up for a minute or two with the choke on, unless it's set too rich. You can pull the choke just enough to keep it running well, not necessarily all the way, then ease off on it as it starts to warm up.

The needle valve in the float bowl has a little conical rubber tip. If it doesn't have a sharp point at the tip it's worn out and can leak. The right carb kit should have some new needle valves and gaskets. The little spring in there likes to jump out and get lost when you're inspecting the needle valve.

The piston looks a little grungy. It's not a big deal to take off the domes and hit it with some carb cleaner. The FSM says to do that every six months. If you spray a bunch of carb cleaner on the linkage on the side of the carbs and follow that with lithium spray grease (also on the outside of the nozzle) the choke is unlikely to stick.

[3ryce]

Awesome guys, great information here! Im gonna book mark this thread. I believe that taking the carbs off and sorta cleaning them up helped a little but still needs more attention. Right now im trying to get it to the point where I can just move it to my house and then ill be able to work on it with more ease and not have to worry about having a time limit on when it needs to be moved. There was something that bothered me tho, I put the carbs back on and everything and started it but with out the air filter and cover on. Choke on and there was fuel spewing out of this small hole. labeled 1 in the picture and the comes from the tubes with the arows pointing to them which lead to the top of the float bowls. the one labeled 2 was clamped off on the other side, i assume this is normal but was wanting some reassurance. heres a picture to show what im talking about.

[Captain_Zeros]

Circled in red is the overflow port on the float bowl, if fuel is coming out of it that means the float bowl valve isn't closing properly, which is gonna cause all kinds of puking fuel everywhere (and running super rich to boot). Take off your float bowl lids and fiddle with and/or replace the valves. Another possibility is that the valve is fine and the metal tab on the float itself isn't making square contact on the needle valve and not closing it properly as well.

[3ryce]

Ok, im making progress on these things, the jet tubes or choke area things, the hoses, were all kinda clogged. So I cleaned thos out and also messed with the float level. I tried to make the floats level by adjusting the metal tabs. Ill look into that lithium spray too. Also I didnt see the needle valve you were talking about tho. It has a plastic ball like thing that the float moves up and touches and moves that up to block the fuel. I can post a picture if you like. Heres a link to a google search of the valve I have. http://www.minispares.com/product/classic/image.axd?type=product&picture=170/CA90.jpg I tried to blow air threw and push the float valve up and it seemed to stop the air flow so if cleaning the lines and adjusting the float level doesnt work im not sure what to do. ha. Oh how fun this stuff is.