Captain Obvious

The red arrow points to the control signal line for the evap system. It should also be tied into the distributor vacuum line. It could be the source of a small vacuum leak. The green arrow points to the vacuum supply line for the power brake booster, and it could be the source of a much larger vacuum leak. If your car runs fine with that brake booster line plugged but won't idle with that line connected, then your brake booster is probably leaking internally and needs attention. You also mentioned that you hear a vacuum leak when you first shut off the engine? I suspect your brake booster is toast.

I built a wooden "fixture" and with enough danger and mechanical advantage, I got my old booster open. Yes, it involved danger, and yes it involved a BF dead blow hammer. And a face shield. Unfortunately, I have not yet found the smoking gun as to why it wasn't working. The symptom was that it held vacuum (even with the engine off), but did not provide any boost. Seems like it would be a problem with the poppet valve, but I can't find anything wrong with it. Current theory is that it is clogged with deteriorated foam debris of what used to be a filter. Tomorrow I will try to figure out a clever way to test the valve in operation without putting the whole booster back together.

Cool. Good luck. Actually, my suggestion would be to put the car back to where it was when it ran good and then take some pics for us. Then we can discuss emissions changes from that point?

Well you have just reaffirmed my reason behind why I have not attempted that maneuver. Good luck... We're all counting on you!

I wouldn’t be ready to condemn the BCDD quite yet, and I am confused by a couple things in your original post... First thing is that there is only one externally visible connection to the BCDD, and that is an electrical one. There are a couple vacuum connections made to the BCDD, but none of them are externally visible. They are all made internally to the throttle body and are not visible without peering into the throat of the throttle body. So when you say "the BCDD was disconnected and lines running to and away from it were blocked off", if you're talking about some vacuum lines being capped... Those vacuum lines originate from the throttle body, but despite how close in proximity they are to the BCDD, neither of them have anything to do with it. One of those vacuum lines should be connected to your distributor and carbon canister, and the other vacuum line is used for the EGR system. So if you're having troubles after messing with those vacuum lines, it's not the BCDD's problem. If you are talking about the electrical connection to the BCDD, that connection is a kind of "dead man switch" such that when that wire supplies power to the BCDD, the BCDD is deactivated and should have no impact. But if that wire was disconnected, your BCDD was active at all times. Second thing is about you hearing a vacuum leak after you turn the car off... As soon as the engine stops turning, the manifold vacuum goes away, and there are two places where that vacuum is "stored" while the engine isn't running. Those two places are in the HVAC system, and in the power brake booster. Both of those systems should have a check valve in series with them to prevent that vacuum from bleeding off, but I'd start looking there.

Cool. Thanks for the check. And props to you in that you certainly seem to have a great handle on the tracking and recovery part. Paired with some deterrent and prevention, it would provide formidable coverage. The deterrent thing, however, can be a double edged sword. You can't plaster "Protected by Geosky" stickers all over the car because part of the tracking and recovery process includes some secrecy. Even if it is a respected system amongst thieves, it is certainly easier to defeat if it's not a surprise. In fact, there was some mention of jamming devices earlier in this thread... I didn't look into the existence, but being an EE, I can attest to the plausibility. If someone is casing the car and knows it has a cell or satellite based transponder in it, it just makes it easier to disable. Big dogs, a siren, a huge chain to an immovable object, a fuel and/or ignition disable, AND your device. They would have to really really want that car. Other ideas? Stink bombs. Iron Maiden played at volume 11. Taser built into the driver's seat. Remotely activated, of course. That "YOU HAVE TWENTY SECONDS TO COMPLY" thing from Robocop...

I got my training in how to use one of those U-Haul trailers from Jim at Memphis 2015. After that, I put that training into practice fetching a derelict project car for my son. Nose first. The built in harness wheel straps do a great job of holding the front end, and I don't think you really need additional straps in the rear, although they certainly can't hurt. If I were hauling something worth as much as Jim's car, I might feel compelled to use straps in the rear. I, however, was fetching something worth much much less. And I was towing with a rented U-Haul truck as well. Their truck. Their trailer. I followed their instructions. Something goes wrong? Their problem. Mostly.

Fuel pump prime would be a perfect application for a momentary switch. But this is a 73, right?

I just took a quick look at my booster, and the input shaft is actually closer to the bottom than the top. Had the direction of the offset wrong. Doesn't really matter since the clamshell can be assembled in many different positions, but I did edit and fix that above.

Woof. And I thought mine was ugly. How can they sell that with a straight face???

I didn't consider the 81ZX booster as I didn't see much of an advantage replacing one difficult to find booster with another difficult to find similar priced booster. The real trick, as Zedhead suggested, is to find a booster with the same firewall bolt pattern and the rest can probably be made to work. That's what I spent a little time on, but didn't turn up anything. I don't even think it needs to be the same diameter. The stock booster on my 280 was the 8 1/2 inch version and I think an inch or two smaller would be fine. I might actually even prefer it. An inch or two larger (as evidenced by the ZX booster "upgrades") works as well. Just a softer pedal I assume. I'm pretty much positive that there is a good alternative out there, but finding it without dimensioned drawings from the manufacturers is hunt and peck. I'd be happy to be part of the team that does the investigative work into an alternative and so far, the asymmetric input shaft compared to the mounting holes has been a non-starter for me.

rc240z, Don't get me wrong... I wasn't poo-pooing your product in any way, nor was I talking to you specifically. I was talking about systems in general. But you're right about "resistance" being relative is exactly why I used the phrase "theft resistance" instead of "theft proof". I do not believe there exists a system that is theft PROOF. The trick, however, is to make the car deterrent enough that does not become a target and resistant enough that it at least not is a successful target. And if all else fails, make it recoverable. I think the perfect system goes something like this: Make it deterrent enough that most threats are dismissed before they start. Make it resistant enough that most threats which were not deterred are at least thwarted without success. Make it trackable and recoverable such that threats which ARE successful can hopefully be reversed. Some additional details that I think are important would be: The deterrents should be non-ugly, non-intrusive, and low on the false alarm scale. The resistance measures should attempt to minimize damage done to the vehicle as part of the theft process. The tracking should be very surreptitious and difficult to defeat. Haha! You can send my consulting fee checks for high level system design.

I'm no expert in the field, but I think the best system would employ theft deterrence, theft resistance, AND aid in recovery in the event that the deterrents and resistance didn't work. Stickers and a flashing LED from Harbor Freight might provide a little deterrence, but won't provide any resistance. Pulling the rotor provides theft resistance, but no deterrence since there is no prior indication that there is a theft resistant force in play. Tracking and recovery aids are great, but are deployed later than desired. It would be best to keep the car from getting stolen in the first place. Who's got that for a non-Ferrari price?

Just call me Mark, Thanks for the pics. I've never seen that before. Ken, There's absolutely no way I would ever ever try to put those rods into place once the hinges are mounted on the car. If you managed to do that without screwing up your paint, then I humbly bow to your dexterity. Heck, I messed up the paint on my hinges and that was while putting them together on the bench. With the help of a BF vice... Sending you a PM as well.

Zedhead, I spent a couple cycles looking for an alternate booster from a different car that I could adapt to the Z, but I was pressed for time and didn't spend a lot of effort on it. The first big hurdle I encountered was that the booster for the Z does not have the input shaft location centered between the mounting stud locations. It's closer to the bottom than the top and seems to be unusual due to that. Things like the size and location of the vacuum port is no problem, but the mounting to the firewall is more difficult to deal with.

Wow Granny, that looks significantly worse than mine. Is that one pit on the vacuum port a rusted hole completely through? I wouldn't have paid for mine if I had seen it beforehand, and if I were to see yours beforehand, I might have thrown up right there on the counter in the parts store. Woof. So I put a couple miles on the car and it works. Doesn't hold vacuum for long after you shut off the motor, but I'm supposed to be headed to a car show this Saturday and it should get me there and back. I'll mess with taking my old one apart and swapping the seals into it some time after the pressure is off. Charles, I'm not sure the lathe will come in handy in building a device to take the clamshell apart, but the lathe will certainly be the perfect machine to reproduce one of these in stainless: Making a new one of those that won't rust and pit like the original is certainly on my list while I've got the patient on the table!

I was so frustrated by this booster that I didn't take photos of the entire process, but here are a couple. This is the front of the booster before I painted it. You can see the pitting. There is also a nice slip-joint pliers shaped dent at about 2:00 : Here's a pic of the snapped retainer loops. You can tell from how far those busted remains are twisted in towards the center that they wouldn't even fit past the dents in the other side of the shell. In other words... They bent those tabs in AFTER they put the two halves of the shell together. Because they certainly couldn't have gotten the two halves of the shell together in the first place with those retainers bent over like that. Nice to see thier blue "passed inspection" paint mark right next to the mangled metal: Here's a pic of the output shaft when I pulled it out. Their training manual says to "apply a small amount of silicone grease" to the seal before installing it: Charles, Next chance I get, I'm going to follow your lead and build some fixturing to take my old booster apart. Or crush it trying.

Ken, Car looks great! I'm "Mid-Atlantic" by some interpretations and I'd love to see the car, but not sure how far south you are. With the hood torsion rods assembled properly into the hinges, there should be no danger of anything springing apart. You put it together off the car and then once the assy is together off the car, you put it on as a unit and it should be uneventful. Also, is it my imagination, or are you going for "turn signal overload" in the front? Whee, have you got any pics of a gas shock mod? I've not seen that.

Let me count the ways. So I bought a rebuilt brake booster from RockAuto: A-1 CARDONE - 535104 (53-5104) - Power Brake Booster $84.79 + $25.00 core = $109.79 I open the box and it's unpainted bare metal, and the metal that is exposed is deeply pitted. This thing was apparently a boat anchory rusty mess that they bead blasted back to "shiny". It's clear that someone sent in their completely tired worn out old dead booster as a core. There are also clear signs of physical abuse. Almost all of the clamshell retainer catches are split open and the case is dented where the master cylinder mounts. I guess I should expect some of that... As long as the pits don't go all the way through and split catch tabs still allow the clamshell halves to seal, I should get over it, right? So I'm handling the unit and it feels slippery on the outside. Feels "silicone-ish"? I'm thinking I just clean it up and throw a quick coat of paint on it. I sprayed and cleaned and wiped and cleaned and sprayed and wiped... Then I sprayed a coat of rattle can black that instantly fish-eyed like I've never seen before. It's like a thousand guppies staring back at me. It's like someone dipped this thing in liquid teflon. Don't care anymore. It's mostly covered. Bolt it into the car and while putting the master cylinder back into place I notice that the output shaft looks shorter than my original boosted. Sure enough, the shaft on my original booster sticks out about a quarter of an inch longer than the rebuild. Try to adjust the shaft length and it's frozen solid. Won't budge. Whatever... So my pedal engagement location will be a little different. I'll re-learn the new position. Put the master cylinder in place and pull out of the garage. The pedal goes almost all the way to the floor before I get any braking action, and when I finally do get any action, there is no modulation. It's almost digital... Either coasting, or face through the windshield. No in-between. Now for those of you who have been through this before, you already know where this is going, but I've never been here before. So, I pry the seal retainer out and remove the (rusty pitted) output shaft. Lots and lots of silicone grease, but you guessed it... no reaction disk. Can't see it in there anywhere and can't feel it. So I take the whole thing back off the car and shake the crap out of it for a frustratingly long time until the reaction disk finally falls out the hole. Put the reaction disk back into place and put the booster back in the car. It works and will get me to my show this weekend, but I think I'm going to build some fixturing to take my old one apart. My old one is clean, un-dented, with the retaining clips intact. I think I'm going to investigate swapping over all the new rubber components from this rebuilt unit over to my old booster. Essentially paying $100 for a "rebuild kit" that I can apply to my original booster? Unpainted, greasy, dented, case with snapped retainers. Rusty components where rubber seals are supposed to seal. Internals not assembled properly. I hate rebuilt components... Starters, alternators, brake calipers, master cylinders, brake boosters. They all seem to be done by people who don't get paid enough to care what they're doing. Sheesh. Stark reminder of why I do my own work. Rant over.

Excellent. See? You had the power all along!

Yeah, I think that shred is what is left of the flap. What threw you off is that you were looking for vinyl, and that's not how they did it. And you know the only reason that your new cover (with the unused listing rod) looks the same as your passenger side is because your passenger side flap turned to dust as well! And you're right... 40 years is a long time for something like that. I'm surprised at how well the foam has held up!

In this pic... I think that brownish stuff hanging from the metal wire (known as a "listing wire" or "listing rod")? is what is left of your original flap. Most of it has turned to dust and it's hard to believe that it ever used to go all the way through the slot up to the seat cover, but I think that's the remains of the original flap.

Yeah, at quick glance, the NTE247 looks like a suitable replacement. Keep it as a backup?

Sheesh. No kidding! And what about busting school children? Busting school children is a terrible, terrible thing. I hear this is going on all over the country. Mean policemen arrest little children and put them in jail in the wrong neighborhoods do they can't even play with their little friends. Imagine... Busting school children.