Captain Obvious

Cool. So they moved that hole. Wonder why. Anyway, glad you're back on the road. I've got a couple months to go yet before they stop salting the roads up here.

And before I forget... I'm planning to cut another vent passage into my aluminum spacer as close to 6:00 as I can. I just rebuilt my booster and even remade some of the internal parts out of stainless, but I don't want that thing to ever suck brake fluid again. Getting that thing apart and together again is not something I plan to make a habit out of!

Yup. Just the tip. As for the o-clock positioning of the vent, I was remembering incorrectly and talking earlier as though the vent passage was in the aluminum spacer, and it's not. My vent passage is not in the aluminum spacer, but is stamped into the booster clamshell. Mine points right at the vacuum hose connection which is in the same place as the one in your pic (mine's a 77). So the bottom line is that my vent hole is at maybe 4:00?

I haven't messed with any of that stuff so I don't have any experience, but I agree that seems a little hokey. With a little web searching, however, it does seem that's the "accepted" solution, and I didn't see any records of failures. Do you know if the Timeserts hardened? Other than the obvious (and expensive) solutions of boring and rethreading or sleeving the entire hole, one other idea instead of epoxy would be to turn (and maybe even thread) some aluminum spacers to take up the gap? Loctite to hold them in place in the upper portion of the recess?

Hmmm... Maybe Klingon? SoHvaD Hija Ha'DIbaH. Qapbej maj.

Yup. I got it. I didn't pay attention to the polarity at the time so I don't know if I got it right, but here's what the reluctor output waveform looks like:

I wouldn't be surprised if the cutter is carbide (which is brittle).

My thoughts on the subject... First, I would be careful with lithium grease on the master cylinder output shaft. A very little bit right on the very tip would probably be OK, but you don't want any of that stuff to come in contact with the vacuum seal that rides on that shaft. I wouldn't want to assume that rubber seal is compatible with that grease. I think a better choice would be silicone based brake grease. Something safe for rubber seals. As for sealant on either of the seams between the parts... I don't think sealant is necessary on either of those seams, but a little sealant between the M/C and the backing plate won't hurt anything. And some sealant between the backing plate and the front side of the M/C clamshell won't hurt anything either as long as you don't block the vent passageway. My read on that vent passage is that it does two things: First, it allows for the change in volume in that (otherwise sealed) cavity when the brakes are depressed. If not for that vent, when the volume inside that cavity were to change, the pressure would change as well. That vent keeps everything at atmospheric. Second, that vent acts as a drain for brake fluid out the hole in the event of a rear M/C seal failure. It would be best if it drains before that fluid ends up inside the master cylinder, but clearly from the amount of fluid inside my failed booster, that's not always the case. One last thought... If that vent is to act as a drain, it would be pointed down, not up. I don't know if it's the original position or not, but mine was pointed at the 5:00 position, not the 11:00 position. Do you think yours was stock original position at 11:00?

Wow. Well that really sucks. I've seen your skill in the other work you have done, so I know it's not an ability issue. Thanks for the warning, and thanks for taking the leap so the rest of us didn't have to.

I don't think any 260 used points. I believe all the 260s (both early and late) used the electronic ignition with the reluctor pickup. If you can't find a proper distributor, you should be able to bypass the TIU and connect the points directly up to the coil like they did for 70-73. Another option? I haven't tried it or researched it, but I bet anything from 74-78 would work (as they're all reluctor pickup). The advance curves might not be "right", but I bet they would "work".

I love the look. It's a view of a Z that I've never seen before. Have you considered clear coat only and do the DeLorean thing? Couple (real) questions: 1) Would the paint guys consider the clean metal surfaces "ready to paint" or would there be additional clean-up that would need to be done? Just a wipe down with solvent, or something more labor intensive? 2) How long do you think you have to get paint on there before things start rusting? I know that in my garage it only takes a day or two for surface rust to start on completely clean surfaces. I'm guessing that the pickling solution in the third tank applied a rust preventative coating of sorts? 3) Do you really think the solder melted? Do you think the bath(s) were that hot?

It's true. So this coming Saturday is going to be mid-sixties and mostly sunny. Great Z weather...

I'm probably the last person on the planet to figure this out, but I was thinking some more about the geometry of the plastigage and what happens when you crush it. As you decrease the thickness and extrude that material into additional width, the change in width is non-linear. The amount that the width changes will go up faster as the thickness decreases: You can see this phenomenon in the reference stripes on the plastigage package. I'm sure you already knew this, but for example, that's why the width change between .003 and .002 is much smaller than the width change between .0015 and .001. I do have a point though, and that point is that you are much closer to .0015 than you are to .002. Still within spec though, so the binding is curious. Of course, the whole spec is only applicable to a crank that is perfectly round, a rod that is perfectly round, and bearings that are perfect consistent thickness in every location. Any high spot or oval anomaly anywhere could miss the gage, but cause the bind. It's too bad they haven't come up with a plastigage that allows you to spin the crank WHILE the plastic is in there and still get an accurate reading. There's a product idea for you. Not that it matters now, but I assume you tried that rod in other locations and the issue followed the rod? I also assume you tried swapping the rod bearings around and same thing. Didn't follow the bearing, but followed the rods? About a torque spec for the force required to spin the crank, I'm not aware of anything.

Cool. Thanks. I don't know how it hooks into the temp lever yet as my non-AC control head doesn't seem to have provisions for attachment, but I'll figure something out. So they used that device to regulate the evaporator temperature by turning the compressor on and off? So what are you going to do about your vacuum test results? You going to replace the compressor front seal and see what happens?

I agree with the assessment about the plastigage. How far out were those two rod ends? Couldn't have been much! So how was it when you turned the crank with (almost) all of the pistons in there moving up and down? The hiss of the new tight rings sliding across fresh sharp crosshatch? Exhilarating? Give you chills? All this talk about bore measurement and the like... Reminded me of this old guy resting in the bottom seldom used recesses of the toolbox. I don't know when was the last time he was pulled out for any reason other than to just admire him:

Here's my evaporator from the 74. I assume the thermostat you were talking about is the device on the lower left of the pic? I assume this is the thermostat you were talking about:

Haven't put it in yet (obviously), but... Normal position with button pushed down (switch closed and the pump will run): Give it a knock on the palm of the hand, and popped (button up):

They look great. Did you put heaters in? I took pics of one of my seats earlier today. I'm guessing you figured out which side was which and don't need pics anymore?

That's fricken awesome!!! Can I bring you my car???

Great work. Weird about the two rods being undersized. Let me make sure I understand what happened... You checked all six with plastigage first, and all of them (including 5 and 6) appeared to measure within spec with the plastigage. But then after cleaning out the spent plastigage and lubing everything up for final assy, the crank bound up when 5 and 6 caps were tightened? The implication here being that the plastigage test was unreliable for some reason or that the spec is actually a little too tight at the lower end?

Well here's a philosophical question for you... The system is normally under pressure, not vacuum. So if it hold's pressure in the correct direction (higher inside the system than out), is it really the end of the world that it won't hold pressure the other way (vacuum inside the system). Many seals are designed to hold pressure in one direction only. Did they do that on the A/C system? Like I said... Just enough to be dangerous.

There was some chatter in this zcon 2017 thread. Not specific to Texas folks though: http://www.classiczcars.com/topic/55922-zcon-2017/

Mak Never heard that, but I like it. I was just figuring that you're only ever going to have to do this once, I would have designed for overkill. Even though it's not a "safety part" like seat mounts, crash safety, or suspension integrity, the cost of failure is pretty high. It'll rip up the underside pretty good if that thing goes out. On the good side, (depending on how loud your exhaust system is), you'll most likely hear knocking around before an all out failure. RE the other comments, siteunseen and I went off on one of our all too often ADHD inspired Blazing Saddles excursions. Sorry for the distraction. Rossiz was going original classic and Cliff and I went with the satirical irreverent version.

Your leak detect efforts sound like they're working great. Holding vacuum undisturbed overnight is the litmus test my HVAC buddy goes by as well. Good luck with that step.

I've got the whole system from my old 74 and my goal is to adapt that to my 77. I don't know what differences there were from year to year, but I'm hoping there weren't significant changes from 74 to 77. I think my evaporator has a little copper line coming off it. Is that the thermostat you're talking about? I don't have any pics of this stuff, but I'll try to snap some when I get a chance. My thinking on my system install is that about the only stock parts I really really need is the evaporator expansion valve stuff and the condenser. Those are the things that are highly physically fit intensive and finding alternatives would be a real pain. I'm thinking that mounting a compressor from a different car is a bracket making exercise that I can handle. And the controls part is also something that I don't think needs to be stock. I don't plan to use the whole vacuum controlled stock system. I'm planning to stick with my manual control system and have a separate way to turn the system on. Of course, I only know enough about HVAC to be dangerous...