Captain Obvious

Actually the factory carbs for your 74 were "Flat Tops". Many people replace them with other carbs like the "Round Tops", or Webers. Which ones are you interested in hearing pros and cons? Because if it involves Webers, I'm not your guy... I know nothing about them.

Increasing the resistance increases the fuel. And there's absolutely no way you should need an additional 1K worth of resistance to get it to run right. There is something else way wrong somewhere else that you're trying to compensate for with that resistor. No way, no how.

I figured that was gonna happen! I was thinking of you when this thread popped up!

The link to 240zlover777 came from the original auction that started this whole thing: https://rover.ebay.com/rover/0/0/0?mpre=https%3A%2F%2Fwww.ebay.com%2Fulk%2Fitm%2F123002344687 Back when this all started, that auction was under the name whitelotus909, but if you take a look at it now, it's listed under the name 240zlover777. And you know it's the same guy because the negative feedback from nix240z is there and the auction number is the old one:

I'd hate to have that thing wiggle under use too. That would be bad. I believe however, that if the locknut is doing it's job, that shouldn't happen. Good luck however you proceed!

Glad to help. My pleasure I would take the opportunity, however, to point out that even the simple 240 had the exact same feature. It just looked different. The "Throttle Opener" system on the 240Z's is the exact same thing as the 280's BCDD system. Does the exact same thing... Limits intake manifold during high vacuum deceleration conditions. So your 240 has it too, they just called it something different, and they didn't hook it to the speedometer. And now that I think about it... I believe they started hooking the throttle opener system to the speedo in 74, so that speedo may be suitable for the 260 as well as the 280s. TMI?

Me too.. I wouldn't worry about that. Maybe hit it with some 600 grit to make sure there aren't any burrs kicked up from the scratching, but other than that, I'd go ahead and leave it.

Of course! Haha!! The BCDD system is part of the emissions system on the 280's. It limits the intake manifold from going sky high under deceleration and making the mixture go all wonky (technical). It limits unburned hydrocarbon under deceleration. The system is only activated once the vehicle speed is above 10mph, and they detect that threshold using the speedometer. There's a tiny little switch inside the unit and that white electronic nubbin (technical again) on the back is an amplifier that takes the signal from the tiny switch and boosts the power allowing it to control devices that need more power than that tiny switch could provide.

I'm sure you probably already know why this happens, but just in case... There are no real seals on the seam between the nozzle and the cylinder in which it slides up and down in the carb body. You don't really need a seal there as long as it's a good precision fit. Sure, it'll leak a tiny amount of air up through that seam when the engine is running, but not enough to matter. Also, under normal circumstances, that seam never sees liquid fuel. But if the bowl level is high enough, and the nozzles are pulled down far enough, that seam will be exposed to liquid fuel. And it's not meant to be liquid tight. If there isn't engine vacuum to pull that fuel up, it'll leak down (as you found out). Natural gas water heater?

Perfect! Sounds like me. I'd much rather be up to my elbows in anything mechanical or electrical than anything to do with bodywork!

It's a 280Z speedo with the 10mph dropout detector for the BCDD system. Oh, and it does have numbers on it. It goes from 10 to 160 just like all the others.

The locknut "locks" everything into place when it's tightened, so I'm not sure I'd worry about it. Unless the threads are so loose that you're worried you'll actually pull the outer tie rod off the inner, then that floppy thread should be immaterial. If the inner tie rod end is tight and doesn't have any play at the rack end, I'm thinking it doesn't matter and I wouldn't burn money just to replace that. So it's a loose female thread spec. Maybe by accident, and maybe on purpose to save costs on the assembly line. But in application, since the threads are pulled into tension with the locknut, I don't think it really matters. IMHO.

Good!

Advanced search in the upper right, and then scroll down to almost the bottom of the page and you can enter a seller's name. I put whitelotus909 in there and it came up "One or more of the seller User IDs you entered was not found." And just as a test, I picked a random ebay vendor that had a bunch of auctions running and made sure their stuff showed up correctly.

Excellent. I love it when a plan comes together. I assume your door closing issues that started this entire debacle have been remedied?

I spy with my little eye... Glassed on rear spoiler and glassed in fender flares on the rear? And unless it's the camera angle, it looks like the two sides aren't very symmetric? Might just be the lighting, but it looks like the left rear arch is higher than the right rear? How are you with body work? Oh, and a brick on the floor at the driver's feet. That's never a good sign. Good luck with the father-son project. That's awesome!

I've got a moustache bar here from a 74 260 and it has the solid bushings. I don't know for positive, but I believe they are the ones that came from the factory and have never been replaced. I'm assuming they softened the whole mounting scheme over the years to reduce noise from the diff. I'm guessing they just kept reducing the contact points over time (with slots in the bushings and wavy end washers, etc) until they got the noise down to where they stopped getting complaints? I'm getting ready to put the slotted bushings in my 77 bar, but I need to figure out something for the upper and lower rubber washers first. Acemon, Were you thinking of trying to mold up something for the wavy washers too, or just the bushings? Also, the material you ordered... Is it rubber (that needs to be vulcanized), or is it polyurethane?

As long as they are clearly identified as reproduction parts and are not (even remotely) misleading to be NOS or made by the OEM, then I have no problem with repros either. It's great to have sources for NLA parts. Just don't try to pass them off as the genuine originals. At any trading venue... ebay, craigslist, etc. So I wonder why the vendor changed his ebay name. The 'whitelotus909' no longer exists. Now it's '240zlover777'. The previous feedback seems to have ported over to the new name.

Very nice. Those results are fantastic. So how do the results differ from straight up bead blasting? In other words... Would the parts have looked much different if you were using s standard bead blasting cabinet?

Actually I believe the choke action has little to do with the fuel level, but is all about the larger gap between the needle and the nozzle. When you drop the nozzle, what you are effectively doing is pulling the needle out of the nozzle and enlarging the jet size to richer the mixture. Larger jet, more fuel.

Cool! Can't wait to see how it works!

I've been thinking the same thing. It's very "un-Datsun" like for them to give a spec that is actually unusable and unmeasureable in reality. I've been thinking there may have simply been a dimensioning mistake there. I mean, it's clear that the documentation is not without error... For example, on that very same page (EF-25 of 72 manual), they say "dimension "H" in Figure EF-46" while it's clear that's a typo and they actually meant "Figure EF-47". So I take that "inside of the lid" dimension with a grain of salt, but without factory confirmation (which will never happen), it's all we got. When I set my floats, I accounted for about two mm for the gasket and the thickness of the lid casting and set mine at 25 mm down from the OUTSIDE TOP of the bowl lid. My car ran great. YMMV. Contrary to a lot of the discussion between you guys above, my experience is that the float bowl level is not that super critical to the overall operation of the carbs. 23 mm down, 25 mm down... Didn't seem to make that much difference to me on a stock engine. Of course, I had gone over the rest of the carbs and everything else and was confident that everything was working as intended. If that's not the case, you end up chasing your tail. No short cuts. You either have the skills to do it yourself, or if not, you take it to someone else who does. Or you sell the car and buy something more mainstream. Something that has a local following of experts in your area.

So what about this ten turns down thing? What's that all about? The ten turns down method is an alternate method of checking the fuel level instead of using a clear tube. Brian claims to have taken some measurements with a straight edge and believes he has determined (unconfirmed by me) that when the fuel level in the bowl is 23 mm down from the inside of the lid, then it should also be 1 cm down from the top of the nozzle when the nozzle is adjusted all the way up (zero turns down). He also contends that this might be not only more convenient a measurement technique, but more accurate. That's what he was alluding to when he says this: "HOWEVER: Even though adjusting the floatbowl levels to 23mm down is a factory setting, it doesn't guarantee that the fuel levels in the carbs are the same." What he's saying is that even if you have set the fuel level in the bowl to be 23 mm down from the inside of the lid, it doesn't guarantee that the level will be in the correct level at the nozzle. The REAL important level is where the fuel is inside the carb, not inside the bowl chamber. So if there is something wrong with the bowl mounting or the bolt holding the bowl to the carb is bent or something, you could have the level in the bowl "to spec", and still have the level wrong inside the carb body. So to combat that, he's suggesting that it may actually be even better to directly measure the level inside the CARB instead because that's what's really important in the end. And to do that, he believes the correct level INSIDE THE CARB is 1 cm down from the top of the fully raised nozzle. Doing the math using the pitch of the nozzle adjustment nut and all that yields the following: A FUEL LEVEL IN THE CARB THAT IS TEN TURNS DOWN OF THE NOZZLE, SHOULD BE THE CORRECT FUEL LEVEL AND SHOULD ALSO CORRESPOND TO APPROXIMATELY 23 MM DOWN FROM INSIDE THE BOWL LID. Finally, after you have used the ten turns down method the check the fuel level, you should put the nozzle level back to it's ballpark setting of 2 1/2 turns down. His not mentioning that is clearly a simple oversight. Check the level ten turns down, and then put the nozzles back where they belong when you're done.

The FSM documents the correct fuel level as 23mm down from the inside of the float lid. And to verify that level, you put a clear tube on the bowl outlet and check it. End of story. But as easy as that sounds... It's not. One problem with that spec and check procedure is that since the spec is referenced to the INSIDE of the bowl lid, you cannot measure it directly (because the bowl lid is not transparent). You need to measure or estimate the gasket thickness and the bowl lid recess depth and then measure down that amount to a dimension on the OUTSIDE of the bowl. Bunch of detailed indirect measurements like that... Not impossible, and you can do it accurately enough, but it's a little finicky. Another problem is that if you are replacing parts, like putting in a new float or float valve, you have no guarantee that your new parts are the same as your old parts, so you won't have any idea where the level is going to end up. So... The FSM describes a procedure for adjusting the float level based on mechanical float position only. That's where they talk about the 14 to 15 mm dimension "H" between the float and inside of the lid when the tang contacts the valve tip. But what they were not clear about is THAT IS A PRELIMINARY "BALLPARK" MEASUREMENT ONLY JUST TO GET YOU CLOSE. The final (and only important) measurement is the fuel level 23mm down from the inside of the bow lid. SO YOU USE THE 14-15 MM "H" MEASUREMENT ONCE, JUST TO GET YOU CLOSE. AND THEN YOU FINE TUNE TO 23MM DOWN FROM THE INSIDE OF THE BOWL LID AFTER THAT USING THE CLEAR TUBE METHOD.

Seriously though, it looks a lot better now. I know the gunk on the outside doesn't affect operation, but I hate messy parts like that. Nice work.