Captain Obvious

So those carbs are the 72 three screw versions. They are supposed to have different needle valves in front and rear. Do you know what Ztherapy put in them?

Yeah, the original part was injection molded. That's what you do when your making hundreds of thousands of them. Or you're @SteveJ And I'm not sure what you meant about a brass tube with a plastic knob inserted... Are you suggesting the possibility of making the finished item out of two parts pressed together? If that's the case, I'd be wary of that. Remember, the bottom of the hole is the spring seat. And it's pressing in a direction to separate the two parts. Yes, in theory, all the force would be on the spring seat (and not on the thin wall tube around it), but there's the transition positions when the spring extends and all that inertia. I don't know how many G's that part sees when it snaps from one position to another, but I bet it's not trivial. Remember the same lubricity the plastic provides to the tip (to let it slide smooth across the switch contacts) will be allowing the two parts to come apart.

I'm no brake expert, but I would want a "stock-like" booster, not the tandem.

Could you put the stock intake snout back on and run the engine like that? In other words... Run the intake tract in NA mode and pull the turbo intake stuff off, but leave the turbo installed. I'm thinking that with the turbo in place you could look inside it while the engine is running to see if the impeller is spinning at all? I'm no turbo expert, but your description of how much force is required to spin it has me concerned.

And remember to take pics in 93 and 94 miles!

I would not consider either ABS or acrylic to be a good choice in the long term. Certainly usable for proof of concept and testing a procedure. Careful with the acrylic as it can be brittle and shatter if you push it too hard. Don't hurt yourself and wear eye protection! This could be done in a drill press, but it's really not the tool for the job. For the spring hole, you want the hole in the center and it probably has a flat bottom. The rounded tip is actually the easy part here... Just use a file while the part is spinning. Heck, since I don't consider it to be a high precision job, that's what I would do on the lathe. Use a file and eyeball the radius.

Got your message and sent one back.

Horn broke. Watch for finger.

I don't have any input into your fan issue, but just wanted to ask... Are you driving on the road when you took that pic, or sitting at idle somewhere? Reason I ask is, the oil pressure is low if you're out driving around. It would be OK for idle, but not for higher RPMs. Based on your posture on the road it looks like your RPMs should be higher than idle.

gotham22, If you want to send me a good part to use as a guide, I'll see if I can make a replacement? And no... I'm not going into the replacement headlight nubbin business unless someone presents me with a credible business case.

I'm not totally thrilled without the smoking gun, but let's hope the problem has been resolved and doesn't come back.

LOL!!

Sorry. My bad. Who am I to say something like that! Objection withdrawn!

Casting in brass??? Pardon my French, but you're out of your mind!! LOL!! Unless you're going to make a hundred thousand, just turn it on a lathe! I could make that part in less than ten hours. Nine-and-a-half to figure out how to make it right, and then thirty minutes to make a good one.

I think epoxy or something 3D printed would both be fine for proof of concept, but I don't think they would last. The thing that worries me about epoxy, would be low abrasion resistance and adhesion to the original remaining nub. And the thing that worries me about something 3D printed, is the very thin cross section where the nub captures the end of the spring. Brittle and prone to cracking? And regardless of what material is used, the original part looks like it melted. So the root failure here looks like it got too hot. That needs to be taken care of first. So since I'm in here... Other than friction resistance, is there any reason those nubs must be made out of plastic? Does it have to be non-conductive? Based on the switch pics above, it looks to me like the could be made out of metal? Brass for example?

Nylon 6/6 would be my first choice with Delrin being a close second. Both are easy to machine at that scale, but I think the Nylon is a little stiffer and stronger.

Awesome! You guys beat me to it! Glad you figured it out and got the idle down to where it belongs. I think that had been suggested before too. Guess it never happened.

chaseincats, This is correct. On the Z throttle bodies*, you have to be careful about how you block off the BCDD. Search around the forum a little and you'll find details. If you can't find them, let me know and I'll see if I can dig them up. * ZX is different.

Yeah, you'll need to spend some time on that. Glad I helped you make it "better"? LOL! First thing I would do now is pull the wire off the new sender when the gauge is at max and see what happens. It SHOULD drop to low temp. If it doesn't, then there's a problem in the wiring or inside the gauge itself.

Yeah, that's the article in which I found the pics I was talking about. This is a 200SX on the left and 510 on the right. Oh, and youtube says the current sensing Z tachs don't have any IC's at all. Nothing integrated. Just discrete transistors.

Who knows... Maybe? Those sites always seem to have stock of any IC you are ever looking for. But do they really? I don't think I'd ever trust them enough to even try

Well this may all be for naught... I got a head start based on the pics from that Dime Quarterly thread I started looking for info on the IC chip - AN603. Based on the logo, it looks like a Matsushita (now part of Panasonic) part, but I couldn't dig up any info about it at all. So if I can't find anything about what's going on inside that chip, I might not be able to do much with it. I mean, I can certainly do a macro level reverse engineering and infer what's going on inside that chip, but that may be about it. And if it looks like there's something wrong inside the chip, I certainly won't be able to get a replacement except from another old donor part. I wonder if they used that same chip in the current sense Z tachs... Those are at least easier to find at this point. Anyway, regardless, I'll do what I can.

My thoughts? If the two tachs were in series and the one in the dash worked fine, then I think there is an internal problem with the 510 tach. I mean, there's a slight possibility it has something to do with the ballast resistor, but I suspect the gauge itself. I also think there is nothing to be gleaned from the seeming "proportionality" of the tach readings. I think that's a red herring. Steve, If you want to send me that tach, I'll open it up and do some reverse engineering on the guts? If nothing else, it'll be a great story about a tach that traveled all over the country. "510 Tach Tour!"

I don't think you need any fancy burping tools for these cars. Just run it, let it cool, and top it off a couple times. That's all you should need to do. The 280's used a recovery tank, but I don't think the 260's did. They were a dump on the ground system. So there would normally always be some air in the system. Hopefully just one pocket corralled at the top of the radiator, but some air.

I've seen plenty of intermittent temp gauge senders, but they're usually random and not repeatable like yours seems to be. First thing I would do is be double dog sure that the coolant system is full. And next is that I would replace the sender unit. It's easy and cheap, so I would just put a new one in there and see what happens.