Captain Obvious

Wait a minute... I suspect there's a little communications issue here. When Blue and I asked what "needles" you were using, we were talking about the long straight needles that install in the undersides of the suction pistons, not the float bowl valves. My suggestion would be to stop referring to the valve that the float tang pushes against as a needle valve and simply call that one "the float bowl valve" instead. So about the needles... The stock needles for the first couple years are N-27's but often they have been replaced with SM needles from ZT. Blue has had issues in the past where the needles that came new in rebuild kits were completely unsuitable for use in the 240 roundtops. So... What needles do you have installed in the suction pistons?

Yeah, beautiful car. And you're right. Way too pretty not to be running better. So I thought somewhere you had mentioned that you were running stock needles, but after re-reading the thread, I didn't find it and am assuming I imagined that. So I second Blue's question... What needles are you running? Did you find that thread where Blue and I were exchanging stories about not being able to get the float bowl levels to adjust predictably? Don't keep adjusting the tang so many times that it cracks off. The 240 floats aren't easy to come by. Last I heard, ZT was close to having repros done, but until they're in stock, you should treat them as irreplaceable? Blue, he's in Atlanta Georgia. If he weren't so far away, I'd pack some tools and go help.

You're smarter than that! Everything Harry tells you is a lie...

I didn't look anywhere near that good when I turned 39. And it's only gotten worse.

Yes you had better. Hope you get to the bottom of it soon. Fuel leaks like that are a pain in the butt. I did a little digging into devices to help find a leak and research indicated two things: 1) The typical human nose is one of the very best detectors to find gasoline leaks. It is extremely sensitive to even small amounts, and 2) The human nose unfortunately gets "saturated" very quickly meaning that you very quickly lose the ability to detect the scent. In other words, it works great, but for a very short amount of time.

I can probably explain why you didn't see gas when the engine was hot. The engine was so much higher than the boiling point of the gasoline that it vaporized almost instantly and didn't form a puddle. I would surmise that's why the smell was so strong, but there was no liquid present. As for why it didn't leak once you got it back to the stable and pressurized the system, that's puzzling. I've wrapped injectors, fittings, etc with a paper towel and use masking tape to hold the towel wrap in place. If there's a fuel leak, it'll stain the towel and show up even once dry. Keep it on for a couple days and then unwrap and look for a stain to see if that's where the leak is coming from while hot. And I agree with the thoughts that there's nothing wrong with giving the clamps a snug-up. As long as your hoses have been replaced sometime in the not too distant past and are not all hard and brittle, give 'em a little tightening.

Haha!! It's my calling.

Oh, and by the way... I think the root issue to all of this is that your carbs are (using technical terms) "completely out of whack". I think you've got mixture issues complicated by float levels, carb synchronization, and possibly vacuum leaks. I think you are juggling multiple different adjustment issues and at this point that I would start over with the basics. Pull the carbs. Clean em up. Adjust the bowl levels with a clear tube on the bench. Don't progress any further until you are positive that the levels are correct. Set the nozzles 2 1/2 turns down and put em back on using new gaskets. Get it running well enough to synch the carbs. And lastly fine tune the mixture.

70-72 rebuild kits makes sense. About not being able to get the fuel level in the bowls to respond predictably to changes in the float tang, I've been there too. Been a while, but I remember having the same unpredictable issues where the fuel level didn't seem to follow the expected path after adjusting the tang. There are a couple threads here on the forum that discuss that issue. but you'll have to search for them. Blue and I were discussing it a few years ago. I unfortunately never got to the bottom of what was going on with my carbs, but on the good side (for me), I got the car running great without knowing and I stopped investigating. I'm sorry, but I don't know what the numbers are on the sides of the needle seats are. I think there was at least one needle valve change in the first three years (70-72) but I don't remember if that was for a difference between front and rear carbs or a year-to-year change So jumping ahead a little... What happens if you just put your old needle valves back in?

Gotcha. Check your float bowl levels (you've got sight glasses so it's an easy task) and go over the whole system with a fine comb for cracked tubes and hoses. Half of them are under vacuum and half of them are at atmospheric. And let us know how it goes!

The 73 carbs were the flat top variety and are very different than everything prior. There is little (if anything at all) that is transferrable from 73 to 70. In other words, So I'm not sure what it is you did... Are you saying that you bought a rebuild kit for a 73 flat top and used the needle valves from that kit in your 70 round top carb? And I'm also confused as to how you left the float bowl level situation. You said you couldn't get the levels correct and then what? You just left them wrong? 10mm high is way off and if you left them there, you'll surely run rich. What did you end up doing with the levels in the end?

Regardless of 25 or 125, it sounds like a great starting point and I hope you have a great time with it! Out of curiosity, are you running the flat top carbs or has someone done a round top conversion some time in the past?

Excellent. Another crisis averted!! Yeah, that's the same alternator test I was looking at in the manuals. What's got me is that the text instructions seem to be in disagreement with the test wiring diagram. I know what they were trying to accomplish, but I don't think the translation turned out very well. Glad you made more sense of it than I did! Glad you got it figured out, and if something insurmountable comes up, remember my offer to lighten your burden. BTW - Are you sure it's 25K miles and not 125K?

I took a quick look through the FSM and didn't find that alternator test procedure. Only thing I found was a test on EE-19 (74 FSM) and it didn't test what you did. Not saying what you did isn't a good test, but I couldn't find that description. So does your CHARGE warning lamp light up when you turn the key to ON before you crank the engine? And what does the CHARGE lamp do once the engine is running? Reason I ask is that while the alternator really doesn't need the charge lamp to be functional in order to work properly, the operation of the lamp can provide some insight into the health and operation of the voltage regulator. Keeping a 74 stock? Cool. You better still be running the flat top carbs! (Edited for the external regulator operation)

I (like you) would like to see the voltage go up as you raised the RPM, but I'm not sure what else you could check. There just isn't much to the system. Couple questions I guess, just to get some ideas moving maybe? You said you tested the alternator and it's fully functional... How did you test it? Maybe the alternator is doing it's best to charge a bad battery that's sucking down the current? Are you sure the battery is in top shape? What does the ammeter indicate? Is it showing the battery is charging? All else fails, I'd get out from under it before it becomes more trouble than it's worth. I'd be happy to take that 25K mile uncharging burden off your shoulders.

I'll go out on the "other suggestions" limb... I made my own. I started with high quality neoprene tubing and heat-set a bend in it. It came from the manufacturer with a bend in it already (probably from being stored on the roll since the day it was manufactured) and I found that I was able to accentuate the already existing bend by heating it while holding in a crude fixture. I don't think I got 180 degrees, but I got more than 90. Maybe 135 or so? Enough that it seemed "unkinkable" to me. Been a while, but I think I made a set from Viton as well (until I learned how bad of an idea it was to overheat Viton...) I don't think I have any pics, but can take some if you would like.

Lots of window trim info in this thread: http://www.classiczcars.com/topic/49617-datsun-280z-interior-trim-question/

I haven't looked at the ZX stuff, but the later Z's used dual pickup distributors in the auto-trans versions. Maybe they did the same thing with the ZX's? That would be an easy way out.

Could you use one of the dual point distributors and use the retarded contact set during starting? You could wire a relay coil in parallel with the CHOKE lamp that shorts the retarded points around the normal ones? You wouldn't have graduated control, but you could switch to retarded with a cold motor that needed choke. Just thinking out loud... I don't even have a choke slot. Although if I DID have one, I'd use it for a lever on 5K pot in series with my CTS and use that as an electronic "choke". I'd even light up the bulb and everything.

What Blue said. When you lift the piston with the little test rod, you disable that carb. So when you lift the front and nothing changes, it's because the front carb isn't doing anything to run the engine and those front three cylinders are just along for the ride. When you lift the rear carb and it dies, it's because the rear is the only carb that's adding fuel and you're running on just the rear three cylinders. If the needles are installed properly (with the shoulder flush with the bottom of the piston), and the nozzle adjustments are turned all the way up (zero turns down), and the nozzles are fully seated all the way up (not stuck down or held down by the choke system), and everything is in good shape (not worn or corroded away), Then I would expect it to be so lean at idle that wouldn't run at all. So again, what Blue said. The fact that the front carb isn't running the front three cylinders with the nozzle all the way up is probably a GOOD thing. If the rear carb is still supplying enough fuel to run the rear three cylinders even with the nozzles all the way up (and even smoke at that!), then that rear carb is most likely a problem. As for checking the needles and nozzles for wear or oval shape? If it's so bad that you can see it with the naked eye, then it's really bad. I can tell under magnification with measurement tools, but I don't have a quick and easy way for you to verify. How much do new nozzles cost? Can you borrow a pair from a known good set of carbs just to see what happens? You're positive you've got the needles installed properly, right?

Yeah if you've got fuel pressure on the needle and seat even with the engine off it's possible that you're bleeding that pressure off into the bowls slowly overnight and starting flooded every morning. The original system with it's orifice based regulator allowed the fuel pressure in the rail to drop to zero as soon as the pump stopped moving. Sounds like your new setup doesn't allow that and you're asking your needle valves to hold that pressure back 100% forever and I'm not sure they're that good. Especially if you're getting a heat soak induced pressure spike after shut down. It might be part of the problem. But that won't cause the long term high fuel consumption while driving though. That's got to be an adjustment or needle or nozzle issue. Keep in mind that the needles and nozzles can look fine to the naked eye and still be out of whack. My experience is that five thousandths (.005 inches) was enough to make the difference between purring like a kitten and stinky eye burning exhaust. If you've got any doubt as to the condition and you've exhausted all other possibilities you might want to think about replacing them. 115 miles to a tank is certainly low.... BTW - How do the plugs look? Are they also indicating a rich condition?

It sounds to me that you're thinking the needles cause the fuel level to rise when they are inserted into the nozzle? If that's the case, you have to remember that unless you pulled the needles out first with the fuel pump still running, the fuel level was established with the needles submerged. That means the fuel level will go down a tiny bit when the needles are pulled out and then return to "normal" when they are reinserted. And the amount of that change (either up or down) is only by the volume of fuel displaced by the portion of the needle that is submerged and that volume is very small. The needles are not splashing fuel up into the venturis when the pistons drop. If you've got fuel puddling in the carb throat, it's not because the needles splashed it there or caused the bowls to overflow because the volume of a submerged needle raised the bowl level. That said, how are you regulating fuel pressure and what does that fuel pressure do when the engine is shut off? I'm wondering if the pressure goes up higher than intended when the engine is shut off and the fuel in the rail expands from heat soak. Are you sure that you're never exceeding 3 psi at any time? Ever? Also, when you found fuel puddled in the venturis, how long had the car been shut off? I know you said you ran the pump with the pistons out and the level didn't change, but if you're looking for a slow leak and the car sat overnight? You could have a small seep around or through the needle valves that you don't see with the naked eye, but over a 12 hour sit maybe it adds up? And about the poor fuel mileage and only getting 115 miles to a tank... Are you sure your needle and nozzles are in good shape? If they had been rubbing in the past or if material has left through corrosion, that will throw everything off. It doesn't take a lot of material removal to have a big impact. If you ovaled your nozzles and/or grooved your needles, then you could be sucking down way more fuel than intended even if the bowl level is correct. Bottom line? My suggestions: 1) Check and set your bowl levels with a clear tube on the bowl outlet. 2) Put a fuel pressure gauge on the rail and make sure the pressures are what you expect at ALL times. 3) Inspect your needles and nozzles very closely for wear or corrosion.

Gotcha. My original AAR didn't work right either. It was mechanically fine, but electrically intermittent. Anyway, welcome aboard and glad you got your car running well. Here's hoping you get to the bottom of the rest of the running rich issues.

There's good info on the AAR in this thread: http://www.classiczcars.com/forums/fuel-injection-s30/47447-help-me-understand-aar-please.html About a third of the way down, there is some discussion about the screw together AAR versions (Look for TomoHawks posts) . Some with two tubes like you posted above and some like one I nabbed off a Pathfinder that has one tube and a hole in the mounting face that ports air right into the intake manifold. I assume you searched around for aar stuff and that thread didn't show up. I couldn't find it with the search function... I'm guessing that "AAR" is too short of a keyword and it doesn't work? So about the mixture running lean if the AAR is ported to atmosphere... If you're running too rich for some reason, then having the AAR artificially lean the mixture will be a positive, right? At least until the AAR heats up and closes. And then you're back to your original rich running anyway. So what was your original AAR doing (or not doing)?

I've seen plenty of flexible of PCB's but never out of fiberglass/epoxy. Nothing wrong with trying, but I don't think it'll take enough of a set unless it was molded like that originally before the epoxy set. The thread reminds me though... I've got a buddy working on a LED third brake light project. Maybe I should poke him and see how that's coming along.