Captain Obvious

Nice. Is that the NNJ club? Or the Long Island maybe?

Your memory is fine. It was added to try to quiet something down back there. But the thing is... I don't understand how it could possible do anything like that. The geometry just doesn't make sense. It's like they got a couple complaints back at the factory and they lit a fire under some engineers butt who quickly threw a half-baked poorly thought out fix at it. Then after a couple years, they took that same fix back out. Probably because they realized it cost money and didn't do anything.

That bronze washer has nothing to do with the bearing preload. It's outside the races. You could get the exact same effect by adding metal to the inside face of the yoke and making it that much longer. Doesn't fall into the geometry at all. Doesn't matter. Honestly I'm not even sure what Datsun was trying to do by putting it in there at all. Doesn't make much sense to me. So, here's to hoping it was simply a measurement area. I'll get those calipers out to you tomorrow and you should have them Wednesday or Thurs. I just can't believe your hubs would be out of spec like that.

But before you go applying force to things, I just have to ask... Do you have the room in the upwards direction for that thing to even move off the rack splines? Reason I ask is if that is the only bolt you have removed, it won't come off the rack because it has nowhere to go (up). So... Did you take the bolt out of the upper end to make sure that intermediate shaft COULD move at all? Is the upper end frozen in place?

Sweet. I love it when a plan comes together! Keep your old one in your glove box just in case? I know it doesn't always work right, but it might get you home some night if the new one go wonky in a different direction?

Ooop... I got mail...

I found one round top needle valve. I have no idea if it's factory or aftermarket, but it is the old style with the hardened steel seat and the regulating spring built into it. It measures .079 through hole, so it's at least what the book says is correct. I'm pretty sure I've got a couple others around here somewhere, but I don't know when they will turn up. I will keep an eye open for them though and let you know if something turns up.

I got this pair of cheapie plastic H4 headlights as part of a larger parts purchase, but I cannot use them because of my state inspections. I might be able to sneak something through that looks more like stock, but these would attract too much attention. $25 for the pair? Plus actual shipping. Local pickup is fine too, as well as delivery to Zcon in Atlanta in the fall.

I took a quick look at the wiring diagram, and I do not believe the fuel warning lamp is activated during the bulb check. @Dave WM do you concur? Also, Here's a fresh copy of the most interesting of the pics from above:

Yeah, I can't imagine what stage of electrical disrepair I would be at currently if it weren't for Wayne's wiring diagram. There are honestly projects that I would have simply not tackled if I had to spend that same time tracing the wires on the stock multiple page monochrome diagram.

Oh, and forgot... Since the last time this topic was active: I filed the offset tab off the AIRTEX / WELLS5S1523 (SU4115) sensor and installed it. It works great.

I'm sure replacing those connectors didn't kill your ECU. Probably something simple like you mixed up the thermotime connector and the WTS connector somehow. If you do that, it'll run pig rich, burn you eyes, and foul your plugs in short order.

I will start digging around here to see what I have. Of course, I have no idea if what I have is factory or aftermarket. And I've also got a number of float valves from flat tops... I wonder if they are the same. I never looked into that. I would be really surprised to find out that the difference going from a L24 to an L28 is enough of a change to push you over an edge like that though. I guess I've seen stranger things, but it would just be surprising. Makes me still wonder if there's something wrong with the delivery system somewhere upstream of the needle valves. Finding needle valves with a larger through hole might fix the symptom, but still might not be reversing the root problem, just accommodating it. Although, if that's the case... does it really matter? Fixed is fixed? :)

The fantastic 77 color wiring diagram was created by Wayne @wal280z. Here's the latest. It's Revision "M". It includes the two changes mentioned above (voltage regulator and illumination light in the Temp/Oil gauge): 1977 Color Wiring Diagram Version M.pdf And if you want to see any of the history of changes, here's a thread with some details: https://www.classiczcars.com/forums/topic/11727-color-wiring-diagram-for-280z/?page=3

I'm not sure there is a "standard" size for the needle valve hole. I wouldn't be surprised if different manufacturers might have different sized holes there. What's the hole size in yours? I've got a couple around here that I can compare when I get the chance. Are your valves original, or aftermarket? And as for the vapor line potentially causing the problem, I doubt it, but it certainly wouldn't hurt to check. I was going to suggest a run with the gas cap off or loose, but I really don't see it. And even if there is a problem with the venting, it's not caused by the vapor line. The gas cap itself is supposed to have a check valve built into it such that it allows air into the tank to replace the volume of fuel removed. If that valve in the gas cap is blocked and doesn't work, you could draw a vacuum on the tank and make it hard to pull fuel out. Although, I'm not sure you would see that stark of a difference between WOT and just cruising around normally. Nor would I expect it to be that fast acting or repeatable.

Absolutely not. The bearings have nowhere near .020 free play. If your measurements are correct and the distance between the bearing seating surfaces is .020 longer than the distance piece, then it won't work. The bearing will certainly bind when you tighten the nut to even a modest (50 ft-lb). Your balls will be pushed together so tight, you'll feel like... Well, like your balls are in a vice. I'm hoping it's just a measurement error. So what do you mean by "scallop"? Can you take a pic of how you're making your measurements? Want me to send you my newly made custom hub-checking calipers? They have been calibrated to a NIST traceable standard and everything. You can use them to make a direct measurement and then give them back to me at Zcon? Be happy to. And the amount of torque really doesn't matter. In theory, all of the pieces down the center have been crushed together taking up all available play. Once all the play has been taken up, there is very little axial movement even as the torque increases. I'm no bearing expert, but IMHO, there should be no discernible difference in bearing preload between say 50 ft-lb and 200 ft-lb. We torqued Matthews bearings to maybe 50 ft-lb at my shop and he was going to do the final torque at home. He bought a torque wrench that goes high enough. On my own car? I tightened them with a 1/2 inch breaker bar and some black iron plumbing pipe until my eyes bugged out just a little. I don't condone or suggest that level of cavalier behavior, but... I didn't measure it, but it was "a lot".

And about your drain plug... M12 x 1.25 is close in both diameter and pitch to 1/2 - 20. It's either metric M12, or someone in the past stripped out the old one and retapped for 1/2 - 20.

Why do you think you're going to have a problem with the rear bearings locking up? Do you think you may have mixed up distance pieces and ended up with the wrong lengths? When I was working with Matthew, first thing we did was check his hubs and distance piece measurements to make sure he had the right pairings. Measuring the distance piece is easy, but measuring the distance between the bearing seating surfaces was a little more difficult. You can hold a block of something against one side and then measure the distance between the two faces with a depth micrometer (or using a caliper as a depth measuring device), but it's a little hokey. In the name of accuracy, I wanted a direct reading. So I donated a cheap caliper to the cause... I ground the internal reading jaws off one of my calipers so they would fit into the center of the hub and provide a direct (no interpolation) measurement between the two bearing faces. Here's the caliper with the top set of jaws ground off: And with those jaws removed, it fits down inside the hub like this:

It's easy to get yourself into a tailspin with a handful of paint samples. I think either of those would work out just fine. I suspect the original paints have all darkened a little over time, so picking the slightly lighter of the two is probably perfect.

Excellent. Glad you got it fixed! My son wanted a car and the one he wanted was derelict with significant engine troubles. I told him I would help him buy it and fix it, but he was going to do most of the work himself. I wasn't going to fix it for him, but I would help him with it. Of course, there were bumps along the way and things he realistically just did not have the experience to do himself, but in the end it worked out great. He's got a lot of sweat equity in that car and a healthy understanding of the work that he did. He doesn't baby it, but he knows that if he breaks it, he'll be the one turning the wrenches to fix it.

Awesome. Best year ever. You got questions? We got answers!

Thinking about it a little more, the method I suggested earlier on how to run a capacity test as described above won't provide information that really matters. Reason being, if you pull one of the hoses that lead to one of the carbs, you have changed the head pressure against the pump. The needle valves are a significant restriction and what you really need to see is how much fuel you push through one or both of them. In other words, what you REALLY need to see is how much fuel gets to the bowls. And with that in mind... You could pull off one (or both) of the tubes between the bowl(s) and carb body(s) and run your fuel pump for a minute and see what you get out. It would probably be significantly less than what you would get if you would check at the rail before the needle valves because the fuel will be split between getting pushed through the needle valve(s) and getting pushed back into the tank through the orifice. Just because you've got strong looking flow at the rail running into an open container doesn't necessarily mean you've got adequate flow into the bowls while in use. It's clear from the existence of the problem that the amount of fuel being pushed into the bowls "in use" isn't enough. It would be interesting (to me anyway) to see how much fuel that really is. There would still be a little error using that method because of the amount the needle valve is opening, but it should give you an idea of the max amount that COULD get into the bowls if the floats were completely hanging and the valves were as open as they could possibly be.

Well good luck, and make sure you tell us what you find! I've got some pics around here somewhere showing the internal guts of the original electric pump. No diaphragms anywhere. None. Two ball-spring check valves. One stationary on the inlet, and a moving one on a magnetically driven plunger. Plunger moves up, pulls fuel in the inlet check valve. Plunger moves down (closing the inlet check valve) and pushes that fuel out through the check valve mounted in the center of the hollow plunger/piston. Reciprocates up and down pulsing fuel out. Sort of a seal around the reciprocating piston simply because it's a precision fit inside the tube cylinder of the pump. Tight enough to mostly seal, yet loose enough that the piston has clearance to slide up and down. I have no idea if that is a similar construction to what's inside the new Airtex, but if I find the pics, I'll post some of them up. Very simple, and no bendy diaphragm to wear out. Fun to look at if nothing else!

Well here's to hoping you don't have to drop the tank. Good luck and I hope you find the root problem!

Nice. What's the gray goober? Looks like silicone sealant, but it shouldn't be inside the tubes. I don't have any silver bullet as a fix for the problem, but at least in theory, the problem has been identified. You said that before you installed the electric pump, it was exclusively mechanical. Did your WOT lean problem occur in that configuration? Is that why you started messing around with adding the electric pump? You can try a dead headed WOT run with the return line to the clamped shut just to see what happens. You can run a capacity test on your electric pump up at the rail by disconnecting one of the lines to a carb. You probably won't get the half gallon in a minute because some of that will be going back through the orifice to the tank. The mechanical fuel pump will also eat up some of the pressure due to the cracking pressure of the check valves built into the pump. You could bypass the mechanical pump with a piece of tubing just to see what happens. Just tossing out some investigative ideas before you pull the tank.