Captain Obvious

The circled screw on the rear carb is your idle mixture screw. It meters air around the suction pistons to lean out the mixture coming through the venturi. The circled screw between the two carbs on the balance tube is your idle speed screw. It meters the idle mixture into the balance tube which is then split for front bank and rear bank. Not having messed with a set of those carbs personally, I would expect the procedure to be... a) Get it to run well and have it be synchronized above idle. For that you would use the nozzle drop adjustment for mixture and the throttle plate opening adjustment for speed. Then Once you have it working above idle, go back and work on the idle performance using the idle mixture and idle speed screws. I suspect all of this sounds a lot easier than it is in reality. One thing to note is that you should be able to get it to idle with the throttle plates virtually closed. Darn near all the fuel/air needed for idle should be coming through the idle circuit and into the balance tube, not past the throttle plates. If you need your throttle plates to be open to get it to idle, then you're not really idling.

Jarvo2, I saw your other post about this and was going to post there, but I didn't because I don't know for sure. Somewhere, somehow, there has to be a way for the vacuum which feeds that actuator to bleed off when the system is not actuated, and I don't know where that vent is. In other words, when the manifold vacuum is not high enough that the actuator is pulling on the throttle linkage, then the back side of that actuator #4 should be near atmospheric pressure, and I'm not clear where the port is that assures that. I asked a while ago above in this thread if that bleed off venting was done in the vacuum control valve, and never heard an answer. So all I can tell you is I believe there needs to be a bleed in that system somewhere, but I don't know where it is. They could have put a bleed vent into the control valve #2, or they may have designed the actuator #4 to be leaky on purpose. I don't know. If I designed it, the bleed vent would be in the control valve and the actuator would hold vacuum. Doesn't mean squat though, since I didn't design it.

Haha!! Don't blame me!! I never even knew what it was until this other thread started... They started talking all French and stuff about halfway down page one: http://www.classiczcars.com/forums/thread47482.html I just figured I would just port that over here and pretend like I knew what the heck I was talking about!!

Yeah, those vinyl stick-ons would certainly be easier to move over to the knob top, but for the knob application, I think I want one of the cloisonnes style instead. I think it would be more durable and "classier" looking. I know it's purely subjective, but any input as to which style above is most appealing?

I'm looking at ebay for Datsun logos that I could use on top of my newest knob, and I'm looking for suggestions as to what would be the best period correct representation for the logo that was in use during the 280Z years. I've found red-white-blue with no surround: red-blue-red with no surround: and red-blue-red with a white surround: Any input from the collective?

Sorry for so many replies... Forgot something. I don't have an original in hand, but I did cut and paste pics side by side. Still need to do something with a color finish:

geezer, Yup, so it does! I didn't read the directions, I just looked at the pretty pictures. Man... can you imagine grabbing a handful of that sucker on a cold Canadian morning? I was going to ask if you had a lathe, but figured that even if you didn't you could come up with an alternative. Send me a PM.

Mikes Z car, If you're asking about the threaded metal base insert, I used aluminum. I was considering stainless but it would have been much more difficult to work with, especially with how much hand shaping I needed to do. The biggest thing I was worried about with the aluminum was how good of a finish I could get, and I'm happy with the results.

Thanks!! I'm not so sure about production though... And this is why: I couldn't make them for that. With alternatives out there, I don't think I could possibly charge what this knob cost me. Of course, mine is way better, but probably not better enough. Diseazd, is the knob you just bought proportioned the same as the original knob? The reason I ask is that there were some of the highly knowledgeable owners discussing knobs in this two year old thread http://www.classiczcars.com/forums/thread37451.html, and the opinion was that Nissan's new offering as a replacement wasn't quite the right shape when compared to the original. I didn't do any more digging than that, but it seems suspect that so many of the forum's heavy hitters unsuccessfully spent so much time trying to find the perfect knob only to find that Nissan has them for less than fifty bucks? :bulb:

Geezer, Cutting the shift map out of that ebay knob sounds interesting. Be warned though... I don't think it's aluminum. I think it's chromed plastic. I might be wrong, but looking at this picture, it's got that tell-tale hue showing through of copper plating they use to get the chrome to stick to the plastic: Not a huge deal, but would certainly make powder coating an impossibility. Would make cutting the shift map out easier though. For nine bucks shipped, you can hardly go wrong for a delicate knob made with shiny finish, and shaped with smart look. Strict and solid fitment, supplies you better performance in comfortable grasp, can help to enhance the spirits of safe driving meanwhile raise the status of your car. :classic:

olzed, Thanks! I'm happy with the shape. Now I just have to get the color right. About the threaded insert? I've got about 25mm (an inch) of threads in there. It's more than I really need for strength, especially since it's metal and not plastic, but that's what I used. My previous inserts were made from brass, but I went with aluminum this time because of the silver color of the base. Here's a shot of the back side of the base where you can see the threaded portion: And I just like this shot because you can see how shiny the base turned out after polishing. I wasn't expecting it to look that clean, but I think it certainly looks to be a suitable replacement for the chromed plastic original. You can tell what kind of camera I'm using! :

Got the chance to work on the metal base. Biggest problem is that I didn't make any templates for the base section, and I no longer have an OEM knob in my possession to compare it to, so I'm winging it from memory! Here's a very rough cut testing on the knob to see if it's even close to looking right. Here's my metal base finished and all polished up. And yes... It's real metal :laugh:: And here's my three knobs all together. I think the base looks acceptable for making it with no template. Haha! Not sure I could do it again, but this one turned out OK: I still need to apply some finish to the newest knob and figure out what I'm going to do for a shift map. I used to have a knob with a Datsun logo in the center. Anyone have leads on inserts that I might be able to use?

Learning as you go is great. Take some time and at least read through the tune up and engine fuel sections of the manual. It will not only add to the learning experience, but it will also help you communicate here. Not sure how to interpret your results with carb cleaner. Usually the typical reaction to a carb cleaner spray around leaks is an increase in the idle speed, not a decrease. Especially if you are running lean. What do you mean by "new" carbs? None of these carbs are new at this point, right?

Progress... I got the rough cut blank trimmed to shape. Here it is compared to my cheap and dirty contour gauge: And here it is cut off from the rest of the bowling pin: Tomorrow I'm going to work on the metal base. ninjazombiemaster, Yeah I remember that thread with the discussion about the shift map. I was looking at yours while it was here and I was considering trying to cast something with it, but I have no idea what I'm doing with that and didn't want to mess anything up. You know most of this is your fault, right? I was perfectly happy with my black plastic knob until I started messing with yours.

I've started my second knob attempt. This time I'm going to really trying to recreate the OEM knob. Step one - Here's my old black knob, and my second knob attempt at the very start :laugh:: Here's what I've got so far. Bowling pin is mounted and first rough cut sizing done: Hopefully more tomorrow! Yes, given enough time, of course! You, being learned in the field of theoretical math and physics, are surely familiar with The Infinite Monkey Theorem. I have one thing to say to you... Ooooo! ooooo! Eeeeeeek! Eeeeeeek!

FastWoman, I understand the juggling priorities issue completely as I am perpetually in the same situation. I've got so many other things I should be doing that I feel guilty when I'm working on the Z. :paranoid: Stack of cement board and boxes of tile? Been there too... Good luck with the project and hope you get your shower soon!! As for the AAR impact on idle RPM, now that I think about it, I have to admit that I don't really know how much of a change you could get out of one that is working properly. I've got mine adjusted such that my idle stays about constant at 800 RPM or so as the engine warms up. If I were to open my AAR up more, I don't know how high my cold idle would go. I suspect I could get a pretty high idle though because you see how small of a window I've got past my shutter when cold. I'm using less than 25% of what that AAR could flow. I bet my cold idle would be 2000 RPM, and as long as it could still close completely, my warm idle should still be 800 RPM.

When you say you have a leak in your throttle butterfly, I'm assuming you mean you have a leak around your throttle shaft where it meets the carb body? Your throttle butterfly is supposed to leak. That's how the engine gets it's air and fuel. But assuming you meant a leaky throttle shaft... I doubt you have enough of a leak to require 5-7 turns down on the mixture nut. If that truly is the case, then your carbs are all wallowed out and need to be repaired or replaced. I can't figure out what you are talking about when you say "the linkage bar/balance screw that shuts the car off smoothly". I have no idea what that means. Might I humbly suggest that you look through the factory service manual and use the same terms for parts that are in the manual. That standardization of terms would make troubleshooting a lot easier. :bulb:

Wade, I championed the exact same theory and it was brought to my attention that the cold clearance spec for the Z is smaller than the hot clearance spec. In other words... It depends on the application. Some engines get tighter when hot, and others (like the Z) get looser. I haven't gone through the analysis, but I suspect it has to do with where the aluminum is. Academic, but thought I would pass that on.

Haha! You looking for something specific? :pirate:

Wade, Yeah, you should be getting more than 100-200 RPM difference out of the AAR. Wonder what's wrong with yours... Haha! So you're thinking that I should get into the AAR rebuild business? What's a new AAR cost these days?

FastWoman, I think what you described to oil the pivot pin would work fine, but I'm not sure there is anything in there to rust. The shutter is aluminum, and I believe the pivot pin is chromed steel. Of course, there's the possibility that you have worn through the chrome plating on the pin and have developed some rust, but I think that's unlikely. Mine wasn't rusty inside, but did have some sticky oil residue from the PCV system. As for getting oily stuff out, the first thought is some kind of solvent, but I'm not completely comfortable with that approach. I know others (TomoHawk for example) have had good success doing that, but it worries me a little for two reasons. a) I don't know what kind of insulation they used on the resistive heating element and I don't know if it would like the solvent, and Some of the shutter blades I've seen have a coating on them that I assume is supposed to provide a thin elastomeric surface to better seal against the inside face of the high vacuum side of the clamshell. Problem is that I don't remember if that rubber type coating was on the Z car AAR, or another one from a different car. I've got a few of them I've messed with at this point, and I don't remember which had coatings and which ones didn't. If I had to guess, I believe the Z was uncoated so it should be OK, but you should take a look inside through the holes first to confirm that all you see is aluminum. Maybe just try to keep the heating element on the uphill side so it doesn't soak in the solvent? I'm wondering if your pivot pin has creeped out some like mine did. You could file the crimped lip off, poke around inside, and then epoxy it back together. Wouldn't be quite as field serviceable as what I've got, but you could file the epoxy off again in the future if you needed to get it open again. A little heat would soften it up too. Do you have a spare AAR or just the one that's on the car?

I understand. I'm in the same boat. I picked up those other wheels and have since decided that I would rather have a better original than a 240 or aftermarket.

I was expecting you to be asking about differences in the keys used for the American and European 260z. So for what you really meant... If you're that serious about it, you might consider making sure everything is in tip-top shape and then get a dyno run done to establish a baseline. You might be surprised by what you are getting out of your current engine.

I'll trade you a 240 "wood" wheel or a Grant GT. :bulb: http://www.classiczcars.com/forums/thread47775.html

The connectors are easy to install... Put the "U" shaped metal retainer clip fully into place before you push the connector onto the injector. The connector is designed such that the retainer metal will push out of the way as you force the connector onto the injector and then "click" into place once the connector is fully seated. No muss, no fuss. Taking them off is much more difficult than putting them on.