Captain Obvious

I've messed with similar idle circuits on other carbs (other than Webers) and they're touchy. There's so little flow at idle that the geometry really matters. I feel for ya. That's no fun.

Maybe the valve was sticking in the guide as well and if the rocker pushed next to the valve stem (instead of ON the valve stem), it might have released the keepers. In any event, I'm thinking that trying to get a look at the piston top would be a good idea.

Man! You've got the worst luck... It's like you just can't catch a break! I'm a little confused about what it was that caused this failure. You said the rocker adjuster was loose and walked it's way back down into the head until the rocker became so loose that the rocker wasn't retained enough anymore and fell out of position. That can explain how your car got off it's rocker, but what's your theory as to how the valve keeper split collets came out? I'm thinking that those split collet retainers should never come out as long as the valve stem is help in tension. Maybe the rocker flopping around in there hit the side of the washer on top and released the tension on the keepers?

Excellent. I don't expect any issues. The only difference I can see between the two systems is that the Z has the vacuum sources for the two solenoid valves in series, while the ZX has them in parallel. Shouldn't matter though since the only time the FICD is actuated is when the system is calling for A/C. Not sure why they put them in series in the first place. Glad you'll be looking into this.

Yes, that tube around the back of the block carried water that passed through the original manifold back to the water pump inlet. With your new manifold, I'm assuming there are no provisions for water heat? I'm no cooling system expert, but I think it's important to have a small amount of flow through the thermostat housing, even when the engine is cold. If that area is completely stagnant, then you run the risk of overheating because the thermostat won't be subjected to the hot water and could instead be sitting in a stagnant cold pool. I believe most thermostats have a small bypass hole built into them to allow for just this kind of issue, but I wouldn't completely block off all those path(s) without first confirming that is the case. Eventually heat will make it's way into that area through conduction and eddy currents, but if you don't ensure some flow somewhere prior to the thermostat getting hot enough to open, it may be too late by the time it does.

Yeah, I was mostly kidding on the crowd funding a traditional mold for the dash. At $100 a piece, it would take 500 of us to come up with the 50K tooling for a traditional mold. I mean, I'd definitely be in for a hundred bucks, but at that rate, I don't think it's possible. I'm surprised someone hasn't molded a fiberglass shell that can be backfilled with polyurethane foam and foamed into position on the existing metal skeleton. Or foamed into place on a skinned original dash ("skinned" as in "had the original black covering removed, but the remainder of the entrails remain).

I agree and have considered the same modification. I like the 280ZX version because it's got the solenoid valves built into it. The only time the vacuum does anything when the system is in transition. When you push a button and change a position, it'll consume vacuum, but once the transient has past and everything has reached it's new desired position, the draw out of the tank should stop. I'll differ from Chas above and say that the only time there would be a problem would be when you play with the controls WHILE you are at full throttle and don't have enough manifold vacuum to refill the tank with vacuum as you consume it. (Negative sense on the "refill" or course... You know... "Refilling a tank with vacuum??" ) It would be worth testing, but I bet it'll work fine. You can get all the testing stuff worked out before I get to installing A/C!

Haha, well yeah... It's a 555! I thought you were looking for super simple simple. If you were willing to put something together using a 555, we could have come up with a solution a page ago.

I'm in for $100. You get thirty of us and you've got $3K you can drop on tooling.

These are not the wires you're looking for. So now while you have those connectors loose in hand, you can make sure the polarity is correct for LED's. Probably easier now than once you have it all buttoned up. I know you aren't going to use the one for the A/T transmission selector, but the other one is for the HVAC display panel, right?

Yup, those are the two I found. I didn't have time to put together a pic for you earlier today and I'm glad you were able to find them without one. Happy to be of service. By the way, in your original post you mentioned a "green female" but what you actually hold in your hand in the pic (and what is on the wiring diagram) is actually a green/white female. I knew what you really meant.

I believe the pair going to the 2 position connector are for the "control panel illumination lamp" and the other pair of independent wires are for the "indicator lamp A/T only" I believe I have found both on the 75 wiring diagram. One of them is directly below the fuseblock on the diagram and the other is horizontally to the right from the first one. I'll clip a pic from the wiring diagram if you can't find them. Let me know.

Exactly. I try not to think about it.

I passed on the chance to buy a Dino a bunch of years ago before the prices shot way up. I kick myself regularly. Thanks for the reminder. On the good side, if I had bought one, then I wouldn't be here to pester youse guys.

I understand. I probably get my hands dirty more often than I should.

Excellent. So you already got a good handle on the measurements stuff. Better than I do, I'm sure! I'm a little concerned about the plan to use a drill press and a hack saw blade to make the grooves though. I understand you gotta make do with what you have available, but O-rings are one of those things where a thousandth can really make a big difference and I'm not sure you'll be able to achieve the level of precision desired to make this work properly. Fit and finish are both important. Do you have any access to better facilities in Barbados? Maybe you could take the parts to one of your metrology customers with some machine tools and tell them it's a test piece to make sure they've got their calibration processes under control? I've been to Bridgetown. I wasn't there for anything industry related so I wasn't looking, but the city is big enough that there has to be other means available. For a cost of course.

Thanks for the update. Looks great so far. When do you think you'll have the big reveal of the finished product?

I hope you can get the screw stub out of the throttle shaft. The threads on the original screws are purposely deformed at the tips after the initial installation. This is so they don't accidently come loose and get sucked down your carb throat. You can usually get them out, but they can be a little tough to get started correctly to reinstall unless you clean up the threads a little. Sounds like you cross threaded it... Might not be good. And about my dimensions above... I want to point out that I'm operating in a non-professional shop with uncalibrated measuring tools. Because of that, my measurements could be off a couple thousandths from what you would get with your measuring tools. My RELATIVE measurements were spot on, but the absolutes could be off some. By that, I mean... I cut all of my grooves spot on at .063 wide and .286 across at the narrowest point. I know that because I used the same measuring device for all the work. But in your shop with your tools, you might measure .064 wide and .285 deep. Or something else the other direction. The point is... Use my uncalibrated absolute measurements above as a guide only for getting close, but determine the last couple thousandths in either direction with a test piece and trial-n-error in your shop with your measuring tools.

I edited the info into the above post, but that doesn't bump the thread. So I'm bumping now it so you know I've been back.

Yeah, and that's why I added the thoughts about the fact that it COULD cause a vacuum leak if the holes are in the right (wrong?) spot. I don't think it would take much of a leak to have a significant impact on idle mixture. Wouldn't make nearly as much difference once your foot was on the pedal, but at idle you really need every air molecule going through the AFM. Good luck and here's hoping for the best! PS - I had a dash cap and I took it off. I'd rather look at the cracks than deal with the cap. I know others feel the opposite, but that's just me.

On edit, I just took out a whole bunch of stuff that you knew already... Teach me to read page two without thoroughly reading page one first. Sorry. Carry on. And what Blue said about that spray bar... That rear block isn't long for this world. Looks to me like the tip of that rear tube has already contacted the lobe. Looks like there is a clean spot wear mark on the corner of the tube closest to lobe #12? PS - I don't like your stamped fuel pump. I know you don't either. Just cosmetic, but I prefer the vintage look.

I used 10mm OD Viton O-rings with a 1.5mm cross section and I got them from McMaster - P/N 9263K295. I do have some spares so if you're interested, shoot me a PM. Listed O-ring dimensions are often nominal or "as installed", so before I cut my grooves, I measured the O-rings to be: .401OD .281 ID .060 cross section With that info and a little trial and error, I cut my grooves to be .286 deep and .063 wide. I also checked the size of the throttle plate screws. They are brass screws M4 x 0.70 x 10 mm long (approx.) and they're thread deformed at the tips for retention. I'm guessing that's why one of yours snapped off? Did you get a half turn or so before it locked up or did it snap right away just from crud in the threads?

I was thinking about this a little more and wanted to talk some about the BCDD's impact on mixture and bring up one other additional thought. If the rubber diaphragms inside the BCDD are in good shape then the BCDD won't have any impact on mixture. However, I can imagine a scenario where there could be holes in one or more of those diaphragms which COULD affect mixture ratio. So to modify what I said up above a little... The BCDD doesn't normally have any impact on mixture ratio, but I can imagine a scenario where there could be holes in diaphragms whereby the BCDD draw outside unmetered air into the intake manifold which CAN affect mixture. What you said above about the BCDD's job to introduce extra air into the intake is correct. But an important detail is that extra air is supposed to have gone through the AFM first. If it goes around the AFM and leaks in past one of the diaphragms, then it's a problem. Mine was leaking internally (which doesn't affect mixture), If yours is leaking EXTERNALLY, then you WILL mess with the mixture. And you don't have to remove the solenoid to test it. You can do this: Disconnect the BCDD at the bullet connector. Turn the ignition key to RUN but don't start the car. Walk around to the engine compartment and connect the BCDD bullet. You should hear a distinct "CLICK" from the BCDD when you connect it. Connect and disconnect the BCDD a couple times and verify that it clicks immediately and there's no delay caused by sticky buildup inside. Or if you'd really rather... it's very easy to pull the solenoid off the BCDD and test it on a bench. Just don't lose the plunger or the little spring.

I found my notes and I evaluated using two different O-rings. Problem is that I never wrote down which one I finally chose in the end and for that, I'll have to take a carb apart. It'll take me a little more time. Give me a little bit...

Duh. Well of course if didn't do it when you were looking for it! You didn't realty expect it to do what you were hoping, did you?? It's going to wait for the most inopportune time to start acting up again! About the EC-5 test... Don't forget that just because you have a good signal at the test connector doesn't mean that you've got the same good signal in the coil of the solenoid valve. You could still have an intermittent at that connector or in the wire leading to the solenoid. In fact, the solenoid itself may be intermittent. But unfortunately you'll never figure that stuff out unless you can get it to act funny while you have some diagnostic equipment hanging on it. So what's the worst that can happen? Your BCDD can become activated when it's not supposed to (like when sitting still at idle) which can result in engine speed fluctuations and (at worst) maybe not returning to idle at all, but instead hanging up a little instead. Forget about it going lean. The BCDD has no effect on mixture, just engine speed. Speed only, not mixture. Think of it as a secondary device that pushes the gas pedal down a little when you lift your foot abruptly. Even though you lifted your foot, the BCDD holds the throttle open a little until the vehicle speed coasts down below 10mph. (Doesn't really pull on the throttle linkage, but does the same thing a different way). Is your car an auto or manual? If it's an auto, there is one additional complication in addition to the speedo amp.