Captain Obvious

Oh, and the reason I posted that video is that it can help give you a good idea of where your pistons are under different conditions. Making it potentially easier to figure out where along the stations you need to make adjustments. Like for example... Just because you are at WOT doesn't (necessarily) mean that you're running at a station way down at the tip of the needle. It depends on the amount of air flowing through the carb, not directly on pedal position. If you have a small camera, you could rig it up to take a similar video of the carb slide on one of your carbs. Might be informative. And about the AFR numbers you're getting... I'm no carb expert, but I've generally found that the SU's run rich at WOT, not lean. Maybe your rebuilt engine flows a whole lot better than stock? Maybe it's something else. It doesn't sound like a vacuum leak to me. That would be more pronounced at idle. A problem with the slides? Like dampers not working right or weak springs? Fuel supply compliance? What happens if you pull back on the choke lever while you're driving? Does everything clear up and look better? Just thinking out loud. ☺️

I assume that with enough equipment and calculations, you might be able to predict what would work "right out of the box", but that's way above my pay grade. I would do the same as Patcon and use the AFR numbers as guidance as to which general part of the needle needs to change. Here's a great video of how the pistons in CV carbs operate. This is a motorcycle, but the concept is the same. You can tell by the sound how much he's into the throttle, and you can see what the pistons do in response. I love this video: https://www.youtube.com/watch?v=tR63vrfhwr8 I don't have time to really work on any details right now, and probably won't for a couple days. But, just for starters... Is there any chance that you're running into a fuel compliance issue? By that, I mean, maybe your fuel system is able to provide adequate fuel at idle, but once you start loading the engine, maybe you're sucking the bowls down? And if you let it idle for a minute before shutting it off, the bowls refill before you get the chance to check them? I consider it a long shot, but just maybe? Something like the banjo filters are partially clogged perhaps? Long shot, but I have to ask.

And if you get totally convinced it's a needle problem and can't find something stock the fits the bill, let me know. I've cut a few custom needles.

Well first two things I would do would be to A) pull the needles to see what number they are, and B) try a thicker weight oil. Paltech probably reused the original N-27 needles, or put in SM needles (because that's what many other people do). Pull em to see what you have? I'm not normally a fan of the SM's but with the number's your seeing, it might be just the thing. The SM's run leaner at idle and richer towards the top. And for the oil, I've gone up as far as 20W-50 in one cer I've messed with. In theory, it won't do anything for steady state, but should help for hard acceleration and throttle blips.

The only thing I'm having trouble managing is getting to the end (most recent post portion) of the thread. All of the tricks that have been mentioned so far are ineffective for me. They work intermittent, if at all. I'm really having trouble navigating... What happened to the thread where we were discussing the site functionality? I can't find it and I can't figure out what I'm doing wrong.

I'm no carb expert, but I don't think a small change in float level is going to have much of an effect on the numbers. Are you sure your dampers are damping? What oil are you running in the dampers? Maybe try something thicker?

Right. The left side has provisions for the "key in slot" buzzer, while the right side does not. That said, I think you could probably use the left side on the right and clip that unused wire off. Haven't looked at the diagram, but confident that would work.

Exactly!! I've had the same discussions here. Not that it'll ever happen, but...

@Patcon, Did you turn up a good source for a suitable stainless replacement? I haven't looked, but if you've already done the work, I shouldn't have to.

Awesome. Let's hope this is the end of it and it's smooth sailing from this point forward!! Good work!

Nothing dramatic. Run it with the system a little under filled* for a couple minutes with the radiator cap off. Then top it off, fill up the overflow tank to "F", and put the cap on. Any remaining air should (in theory) work it's way out of the system over the next couple heat/cool cycles. I've not found the Z to be one of those cars that really needs a complicated burping process. * The reason for the underfill is if there is a big air bubble in there somewhere it will expand much more than the liquid coolant will. And if the system is full to the top, it'lcould belch out the top of the radiator.

Yeah, I assume the mention about the oil pressure gauge by Mike was simply due to the fact that with the dash out, you wouldn't know if you had an oil pressure issue or not. But if you didn't have any sort of oil pressure issue beforehand and the only reason you were messing around with the dash was to make it easier to get to the HVAC system, then I believe the concern is unnecessary. Glad to hear it worked out so far. Remember that it may take some time for the whole coolant system to come up to pressure. Oh, and I'd approve of a picture of you driving the car without a dash installed. Slow enough to guarantee you weren't speeding of course, since you don't have a speedometer. Hahaha!

@kats might have some suggestions?

There have been reports of the engine not running if the tach resistor is removed, but I have not verified that behavior. Seems unlikely to me. But in any event, having the dash removed would have the same effect as removing the tach resistor. I can't see any reason it wouldn't run. None of the EFI stuff goes through the dash harness. And from Mike's list above... You obviously won't have an oil pressure gauge.

My 280 starts smoother and easier than that. Even when cold and without a CSV. And if I prime the fuel system first, it starts even easier.

Glad to help. And as I continue to work through stuff here, I'll keep the documented updated if I find anything else that needs attention.

Here's the latest wiring diagram. I changed the wire color leading to the rear tail light assembly. At the hazard switch and the combination switch, the rear brakes/turns use a W/B and W/R pair, but somewhere inside the harness, they change to G/B and G/R pair by the time they get to the rear of the car. I also changed the portrayal of the rear light assemblies to show the bulbs inside. Note that in later 240's they changed one of the dual filament lamps in the back to a single filament. The car I'm working on is mid 1970 and I've got two dual filament bulbs on each side in the rear. <V6.0> _obvious 240Z Wiring Diagram 6.0.pdf

Thanks for the fog light pics. So my "F" switch clearly is just something that a PO stuck in there and I'll never know the intent. I'll pull it and plug the hole.

Assuming you could find a suitable stainless, I think it would work just fine. I think the rust you often see on them comes from the non-stainless parts that come into contact with the shims, not the shims themselves. In other words, I don't think the shims are rusted at all... I think that rust is just mechanically transferred onto them by rubbing against other rusty parts. @Patcon, are the shims magnetic?

Glad you got it worked out. Perfect timing. I'll be posting a new version with the changes to the rear lights soon. You can plot out the new one then.

Sendcutsend has .030 thick stainless. That's the thinnest they list. @Patcon, what's the thickness of those anti-squeal shims?

I took a peek behind the dash today and there isn't anything hooked up to the "F" switch and my blue tape Easter Egg is still intact and unwrapped. I did make another discovery though while I was back there as well... The wire colors for the rear rear taillights needs work. There are some errors on the diagram.

Cool. Sounds like good progress. So how's the lean running thing? Is that still gone?

Wow! No kidding you've been busy!!

Funny you should mention that... I haven't dug deep into the details yer, but I got this going on here. Thoughts?