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Cooper260z

Is one carb missing a linkage?

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I bought this pair of SUs for my 260z and I think I’ve finally gotten to the actual step of putting them on the car but I’m noticing a couple inconsistencies with the two.
One carb doesn’t have a piece of linkage that the other carb does, and one carb moves the  Cylindrical thing at the bottom of the carb (that I assume is fuel related) and the other doesn’t. 
 

There could be nothing wrong and they’re both acting as they should as far as I know, this is my first time with the SUs so if someone can tell me what is or isn’t wrong here that would be appreciated. 
 

The picture highlights the present and missing linkage, and the thing at the bottom that moves only on one carb

394E468D-361C-447F-9613-13761C9520E4.jpeg

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Looks like a three screw SU. The one on the left is missing connection for the mechanism. Here are some picture of my 3 screw carbs mounted. Hope it helps. Also the Ztherapy site may help too 
connects between those two marks

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08CF8AFD-7337-4D4E-B5D5-2B6DE08CCF63.jpeg

F882FE44-BB16-48EF-8F95-BA4B07A8BCA3.jpeg

B6442991-641D-449D-9E65-D78DBBC293DE.jpeg

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On the contrary @7tooZ they are four screw and the one on the right is missing the piece. Thank you for confirming that I am missing that piece 
 

Is that piece available? The real bummer is that I had another set of carbs but sold them thinking I didn’t need the extras. 
 

And there’s still question of the moving thing on the bottom. Are they both supposed to move? And if so how can I get the out her one to move?

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You always need extras!! That's why we hoard stuff...

You're missing the choke linkage bar. The part that moves is the fuel nozzle. It moves down as a choke to add more fuel when the car is cold. They both need to move the same way when on the car and relatively the same amount. Pay attention when you get them on the car, they can stick in the down position and cause idle issues 

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Just to confirm the answer you already got... Yes, you're missing a piece of linkage.

The piece you're missing is part of the choke system and because of that, the choke will not function on that carb. The rest of that carb will work fine, but the choke will not.

As far as getting a replacement, I have about a 0% expectation that you can buy that part from any normal commercial vendor or dealer. I think you'll need to find someone who is breaking up a carb into parts for some reason. I've got a couple spare parts for round tops around here somewhere and I'll look, but don't get your hopes up.

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2 minutes ago, Patcon said:

Pay attention when you get them on the car, they can stick in the down position and cause idle issues 

And that's a good point too. I don't remember exactly where in the linkage system the return spring is for the choke.

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Ztherapy might sell you the linkage

I have found the reason they hang up is usually the wrong fuel lines to the nozzle or the long bar is misadjusted and is pulling the nozzle to one side, jamming it in the carb body

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Oddly enough though, the carb that has the functioning fuel nozzle is the one that’s missing the linkage. So in theory I could use the carbs but wouldn’t have any choke capabilities?

Edited by Cooper260z

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What do you mean by "functioning nozzle"?

And to answer the question... As long as the return springs are still pulling both nozzles up, then yes. You can drive the car even with that linkage missing. You won't have any choke capabilities and it may be a bear to deal with until it warms up, but yes.

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So on the carburetor that’s missing the linkage, if I pull the choke lever up (as if it were on) that nozzle as @Patcon called it, goes down and out. 

On the carburetor that has the linkage, the nozzle doesn’t move 

3CD01EB5-B558-40F5-AF5A-AC844F8A53D7.jpeg

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Sorry... All that stuff I said before was wrong. The piece of linkage is what bumps the idle speed up when you pull the choke lever. The choke should work fine, but it's supposed to raise the idle too, and that won't be happening.

Not sure why your other nozzle doesn't drop at all. I'll have to take a closer look at the pics...

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When you get a chance, can you post a close up pic of what the front carb does when you pull up on the choke lever?

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When I pull the choke lever, the throttle plate moves a little bit and it moves the linkage that goes to the nozzle but the nozzle doesn’t move. I can’t pull the nozzle out by hand either like I can with the other carb 

CECDBA79-A249-464D-A187-200A2DD08D23.jpeg

4A3D931D-E834-4712-ACAB-E7D047BCBCA4.jpeg

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It sounds like either someone put the linkage together wrong on that carb and it's binding up, or your nozzle is just stuck frozen in place.

If you take out that little screw (the really chewed up one) out of the bottom of the nozzle and completely separate the nozzle from the linkage... Can you pull the nozzle out then, or is it still stuck?

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The nozzle is still stuck after disconnecting the linkage. 
Something els I noticed is that I can twist the nozzle and the thumb screw (adjuster?) and the hex closest to the carb body will all twist. On the carb with the nozzle that moves, only the nozzle will twist, the thumb screw and hex stay where they are. 
If that makes any sense at all...

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11 hours ago, Cooper260z said:

The nozzle is still stuck after disconnecting the linkage. 
Something els I noticed is that I can twist the nozzle and the thumb screw (adjuster?) and the hex closest to the carb body will all twist. On the carb with the nozzle that moves, only the nozzle will twist, the thumb screw and hex stay where they are.

Yeah, there's something wrong with that whole nozzle assembly. With that little screw out, the nozzle should slip freely in and out inside the alignment nut. The get corroded and stuck sometimes, or maybe the whole thing is so badly misaligned that it's jammed up against the needle inside the carb. That bottom assembly should not spin. There's something wrong down there.

So what's the history of these carbs? It sounds like someone who really didn't know what they were doing had them in pieces and didn't do a good job of putting them back together. (Sorry if that was you.....)

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10 hours ago, Cooper260z said:

How intuitive! I’m sure that system has never failed anyone...

LOL. Yeah, never.

Just because the adjustment method involves bending pieces of the linkage, you think it's crude or something?

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I got these carbs from a guy that said they ran great, and in fact said that he had a mechanic friend that used to work on his Z that really knew what he was doing... guess I’ll just play with them and see what I can get to happen before I either get different ones and have them rebuilt 

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12 hours ago, Cooper260z said:

How intuitive! I’m sure that system has never failed anyone...

Well no problem. If you have a better idea of what to do go for it. I was just trying help. Those are 20 year old carbs that worked perfectly until I blew out a seal. So I had new seals and bearings put in by the company that sold them to me 20 yrs ago. Came back beautiful and started right up on the first try. All Good here.

Edited by 7tooZ

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It just seems like the bar could break if they took too much bending back and forth to tube. But if it works, it works. 
 

I was able to get the nozzle free after taking it apart and playing with it for a bit. It was just gummed up and stuck. 
Im still missing one of those bars that pops the butterfly open but I think I’ll still install the carbs and see how they work. I’m hoping starting and warming the engine won’t be too hard only missing a one piece of the choke system as long as I help it a bit with the pedal 

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5 hours ago, Captain Obvious said:

LOL. Yeah, never.

Just because the adjustment method involves bending pieces of the linkage, you think it's crude or something?

Here's crude! Why in the hell would someone need to do this?

Screenshot_20201019-144309_Samsung Internet.jpg

 

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Yeah, looks like someone got a bit aggressive with some of these screws. Not sure what that was about 

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One positive thing is you have the knurled knobs to adjust the nozzles. Mine are a pain to move up and down. Very painful on my sensitive fingers. LOL

Screenshot_20201019-152929_Samsung Internet.jpg

 

 

 

 

 

 

Edited by siteunseen

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