Captain Obvious

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.....)

What do the wires do? I think I can help with that: Blue is +12V power in. Hot when in ACC and ON. Blacks (two of them) are grounds The one on the 6-position connector is used as the low side power for the radio, and the bullet is used as a speaker ground. White/Black is also a speaker ground. I think it just gets connected to the black ground wires in the car harness. White is right hand speaker output. Black/Red bullet is left hand speaker output. Green/White is panel illumination high side. Goes to the headlight switch. Red/Blue is panel illumination ground side. Goes to the rheostat. Does that make sense?

Sorry, but I don't understand your last post... I took a quick look on ebay and found that they ARE commonly available used. And cheap. You say they aren't available used, but then you say it's common to replace them with aftermarket? I'm not sure if that was a typo or what, but I saw lots of them on ebay.

So sorry for your loss.

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?

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?

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...

And forgot... Yes, the real solution to the confusion is to actually show both ends of that little stub harness on the diagram. It's really Datsun's mistake, not yours.

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.

Sweet. Hope it works out. And it's nice that it's from a Z!

I think the schematic matches the car fine. The connectors shown on the wiring diagram are a six position spade and a pair of bullets. On the car end of that sub-harness, you've got a six pin spade and a pair of bullets. Just like the diagram. The confusion comes from the fact that the connectors built into the back of the radio are not shown on the diagram at all. The diagram shows it as if the wires were hard-wired coming out of the back of the radio (just like they did on previous years). So if you plug that little sub-harness into the back of the radio and pretend it's all one piece, then the wiring diagram is spot on. The problem you're having with 6+2 or 5+3 is that the 5+3 is completely ignored on the diagram.

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

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.

Yes, the linkages are different. Remember back on page 1: And about the anti-backfire valve... It's got three connections: 1 - High vacuum from the balance tube side 2 - No vacuum from the air cleaner side 3 - Control line to open the valve when the intake manifold vacuum goes high enough The connection that you put the little air filter on is the no vacuum fresh air side. The other two ports connect to vacuum sources. Does that make sense?

Haha! It's a calling. Seriously though... Glad to help!

Agreed. I'll do the same.

Yeah, I would keep the AB valve if you can. You could slap a little cone filter on the fresh air end just to keep the bugs and birds out. The ones that a lot of people put on their valve cover nipple? Something like that? And yes, the 260 balance tube is much more complicated than the 240 version. If you're positive that you won't be running EGR then you can make things look a lot less basket of snake-ish by switching over.

Trooper is holding the leash, right? Haha!!!

Nice work. I would have done the same. That bulge is obviously where the weld bead overlapped near the end of the bead. Doesn't look like you had to remove much and hopefully you're home free now.

The reason you had oil spilling all over the place is because the original strut (as described in the factory service manual) did not use an insert. They built the damper right into the strut tube. The insert that you substituted for the original design takes up much greater volume than the original. And because of that, there is a lot less volume left over for oil.

That's fantastic! Enjoy the car and drive safe!

I'm no expert, but that's my read as well. And I don't think the carbs would even be that big of a deal if we knew what happened. I still suspect that sometime long ago, the carbs were sent off to be cleaned and tuned and all that, and the ones that came back aren't the same ones that were sent off. From what I gather, some of the big name players in the round top carb realm do that. You send them a pair, but the pair you get back are not necessarily the ones you sent them. At this point, it's mostly the denial that gets me. The seller knows the car is worth more if it's that "beacon of originality", and hence, isn't giving up on that. If I were a judging this car at a show in a high quality, high profile stock class, I would ding it for the wrong year carbs. I just hope the new owner understands that could happen to him. And a defense of "Well the guy I bought it from said they were OK." wouldn't change anything. Haha! I think I'm going to stop talking about it... I don't think I'm adding value anymore.

That looks leakproof!! Tell dad thanks for saving you the trip to the store!

Right! And taking a cue from Arlo, there was a third possibility that we hadn't even counted upon. "Yes, they are the three screw carbs and someone at the big important show already raised the question if they were correct. And at the big important show nobody knew for sure if it was right or not, so they gave it a nice trophy anyway. So with my trophy as evidence, I claim that they are the right carbs for the car." I believe it's a variation on the 34th street defense. He says that people had seen three screw carbs on 71 cars. Well no duh. The transition date (according to the admittedly little research I did) is August or September 71. I could see those cars could maybe be titled as either a 71 or a 72. But...... The car in question on BAT is a whole year BEFORE that!! Door jamb plate says 8/70. I'm nearly 100% certain that the intake manifolds are the E46 version that works with the four screw round tops. The three screw round tops were not matched to that manifold because of the coolant scheme. Instead, the three screw carbs were paired with the E88 intake manifolds. So my question is... What manifolds are on there? If they are three screw carbs bolted to the E46 manifolds, then shapes of the carb faces do not match and the coolant holes on the carbs are hanging open to the wind. So it's a 70 head, a 70 block, 70 manifolds, 70 everything...... Except for the 72 carbs. Came from the factory like that. Really?

Gotcha. Sorry. In some instances, "age" is more of a factor than mileage. I guess I was giving them a pass on the brake booster as one of those.