Captain Obvious

I'm sure this would be available from generic sources and I'll measure an original pilot when I get a chance. Are you thinking you want to use that roller option? If so, I'd advise against it. Might just be my conservative nature, but I see more downside than up. In the meantime, I do have this from sometime past:

The way the shoes expand is the adjuster lever arm grabs a tooth on the geared wheel when you pull up on the hand brake. But when you release the hand brake, the lever slips across the geared wheel without turning it (because of the shape of the teeth on the wheel). Keep yanking the brake lever up and then releasing, the shoes keep expanding one tooth at a time. UNTIL.... Once you reach the point that the shoes are spread far enough that the lever travel is so short that it does not catch a tooth when you pull up on the handle. At that point, the wheel will not turn any more until the shoes have worn enough that the lever travel will grab a tooth. That's the mechanism that keeps the shoes from wedging themselves in place.

Here's some reading that might help. https://www.classiczcars.com/forums/topic/21910-76-datsun-280z-throttle-sticking/page/2/ https://www.classiczcars.com/forums/topic/45152-sticky-throttle-body-hanging-idle/ https://www.classiczcars.com/forums/topic/57126-sticky-throttle-body-fix-delrin-bushings/

If you can blip the throttle and the idle returns to where it belongs, then the issue has nothing to do with the BCDD. That kind of hanging idle is a mechanical issue either with the linkage, or with the throttle body itself. I had that problem with my 77 and after lots of investigation and changes, the only thing that fixed it was to switch to a completely different throttle body. I ended up adapting a Sentra throttle body and adding a cable linkage. Bunch of work, but it's smooth as silk now. And I'm near Philly. Lancaster is about an hour and a half from me. Depends on the traffic (which is often terrible for some unexplained reason!)

Yeah, the BCDD can be troublesome. First thing to try would be to confirm that's the issue. If it's not all messed up inside, you can hopefully adjust to solve the problem.

The hanging RPM's might be because of the BCDD, but it has nothing to do with that vacuum line. In fact, that vacuum connection has nothing to do with the BCDD. It LOOKS like it has something to do with the BCDD because of it's close proximity, but inside, it makes absolutely no connection to the inner workings of the BCDD at all. There are two vacuum ports on the underside of the throttle body: One of them is a ported vacuum source that supplies vacuum advance to the distributor under light load conditions. The other is a ported vacuum source used to actuate the EGR system under light load conditions. If you aren't using the EGR system, you can cap off that ported vacuum nipple, but it won't (shouldn't?) do anything to change your hanging RPMs. But if it's hanging open, you should cap it off.

Haha!

Well then, I suggest that maybe you've never actually experienced a damper that is working correctly. Either that, or I've got delicate soft fingers while you've got rugged manly-man lumberjack hands. 😀

Yeah, it's beautiful. Have you seen that one in person yet? He and I have traveled together to a couple Zcons in the past few years. You may have seen it at Atlanta or Nashville? And the work being done in that pic... He had lowered the car some bunch of years ago and always thought the rear was too low. So he added spacers to the the top of the rear struts to raise the rear end a little. He had to disconnect the rear brake hoses to get enough travel on the strut assy to get access to the top to fit the spacers. We had just finished bleeding the brakes and I was enjoying a refreshment while he cleaned up the bleed nipples and buttoned up the details. I haven't seen the final stance yet. Fingers crossed it looks a little less squatty in the rear than it did before and he's happy. It's still on stands now though because he's also cleaning out the gas tank at the same time and that portion of the work isn't done yet. I brazed some of his tank vent nipples closed and he's working on the final tank cleaning. Should be soon.

I drank a beer while I watched a buddy work on HIS Z. That counts, right?

I (thankfully) have not had to go back into my struts since I put the KYBs in. I'm actually kinda hoping I never have to go back in. But if I do, I'll be sure to post my findings.

Me too. Hope they are both doing well!!

I saw the hint you dropped earlier and I was wondering if we were gonna get more of the story!! Hahaha!!! 😀 If, in fact, it had actually happened. Which it didn't.

Hahaha!!! We'll need to work on that!

No, it's not the wrong sensor... It's the aftermarket replacement that is (almost) "form, fit, and function" compatible with the original. The aftermarket one piece design still seals on the same beveled edge and functions the same as the two-piece original. The O-ring on the new version is not intended as a liquid seal, and is actually not even necessary at all. I think they put it there as an attempt to keep junk out of the threads (from the outside getting in). So, that said, what is it about the original two-piece design that is not replicated by the aftermarket one-piece? Answer is "the ability to clock the connector to a convenient position" before you tighten it down. With the original sensor, you could turn the body to whatever position you wanted before you did the final tightening of the flare nut. With the aftermarket design, when it gets tight, the connector position ends up where it ends up. But other than that, they should both work just fine.

Haha!! I didn't even notice that, and I wrote it!! So just in case there was any confusion about what I meant... I was trying to say that I think I've not never seen that bracket, ever. 😄

I don't think we ever talked about the condition of the dampers themselves. We probably should have started there, but anyway... Is it difficult to lift the pistons? When you stick a finger into the carb mouth and lift the piston manually, you should be fighting the damper oil. And even with ATF, there should be significant resistance to pushing the piston up. It should drop easy, but it should be difficult to lift. If the damper is working correctly, it should take multiple seconds to manually lift the piston, and it should leave a dent in your fingertip. And then it should drop with a "clunk".

I'm not claiming to be able to identify every 280 part on sight, but I don't think I've never seen that bracket. Are you sure it's a Z part?

Yeah, I'm assuming you could simply make it richer by turning the nozzle knobs down some, but let me guess.... If you do that, it idles pig rich? And probably rich at light cruise as well?

Well let us know how the 10W-30 fares when you get a chance to test it out. I was asking about the needles because (as emccallum mentioned), I thought that the stuff that ztherapy did came back with SM needles. In any event, if you're still running lean with the oil change, you might want to pull a needle and have a look for confirmation. Have you verified the float bowl level using the clear tube method? That could have some impact on mixture too.

Oh, and a couple other details about the carbs... Are you running stock needles? Stock springs?

If you have 10W-30 laying around, I'd try that. Are you double dog sure you got all your vacuum leaks sealed up now?

Spot the Bot!! @Mike

That would have to be a really bad guide to pass that much oil. Did it smoke while running? I'm thinking maybe stuck or faulty oil ring?

Awesome. Hope that's the smoking gun and the problems all go away! I was already struggling to come up with scenarios of what could cause your problem, so I'm hoping we're done with that! Haha!! 🙂