Captain Obvious

Excellent. It's always a little tentative to provide that level of detail when I don't have the official documentation. Glad that worked out and glad you got your test done.

My documentation for the early years is sketchy, but I believe it goes like this: Green/White is the +12 side. Black is the ground side. I'm assuming there's only one G/W in the dash harness, and you should be able to pick it up at the headlight (combination) switch connector. You should use a current limited power supply if you've got one or put a couple amp fuse (like 2A) in series with your power source just in case. Maybe turn the dimmer control full dim before you make any connections and then turn it up after you have power on the circuit? And anecdotally... They changed the wiring scheme somewhere along the way. The earlier cars (maybe through 73?) had the dimmer on the high side and the later cars (74 on?) had the dimmer on the low side. But I don't think it matters for what you're trying to do.

Gotcha. That will work to vent the tank (in both directions). However... A concern about doing it that way is that you're going to smell it since it will vent into the passenger compartment.

Just make sure you've got ways for air to both enter and leave the tank before the vacuum or pressure reaches levels unhealthy for the system. If you simply remove the vapor/liquid separator tank and just cap everything back there, you're asking for trouble (even if you've got a later style gas cap with the check valve). You'll be OK for vacuum, but pressure will still be an issue. And simply connecting the nipple on the tank that used to have the "orange" hose on it to the nipple on the filler neck won't do anything to relieve pressure or vacuum. It'll enable you to get more fuel in the tank at the gas station, but it won't do anything about vacuum or pressure buildup.

That link shows clearly the perils of letting the tank draw a vacuum. It doesn't have any pics of a tank that has bulged outward from pressure, but some of those may be out there as well. In normal operation the tank can draw either a vacuum or develop pressure and you need to have provisions somewhere in the system to account for both of those possibilities. That drawing on the previous page of this thread looks to recommend completely eliminating all the venting in the system. Am I reading that right? Are people really completely eliminating the vents on their systems?

Yup. That's the one. They called that the Flow Guide Valve, and it's purpose was to vent the gas tank pressure into the crankcase when the engine wasn't running. These vapors would be "stored" there until the engine was running, and then once the engine was running, those vapors were pulled into the intake manifold through the PCV and burned. I'm skeptical as to how effective an engine crankcase is for "storing vapors", and apparently the emissions czars were as well because starting in 74 they went away from the idea of storing the vapors in the crankcase and went to the activated carbon canisters instead. I've not had anything early enough to have a flow guide design (everything I've had is 74 or newer), but I believe the years with the flow guide were supposed to have a non-vented gas cap. The flow guide is supposed to direct air from the air cleaner housing into the tank if the tank draws a vacuum. In other words, the later years used a check valve in the gas caps, but I think the earlier years did that check valve function as part of the flow guide valve. In any event, there still needs to be a way to vent pressure out of the tank.

Not sure who your question was directed to or what bumps you're talking about, but if you're talking to me and you're asking about the bumps on the top side of the gas cap, then those are air holes that lead to the atmosphere side of the check valve built into the cap. When the pressure inside the tank gets low enough, the check valve will open and air will be pulled into the tank through those holes. Air isn't ever supposed to flow out of those holes... Only in. If you look carefully at the pic above with the paper clip... The clip is holding the check valve open and you can see the little rubber seal under the disk that the clip is lifting up. Pull the paper clip out and a spring pulls that disk back against the underside of the cap thus holding the check valve closed. And if you're not talking to me or weren't asking about the bumps on the cap, then please disregard this response completely.

The cap is vented, but it's a check valve that only lets air INTO the tank as fuel is used. It will not let pressure out. PRESSURE that's developed in the tank is supposed to vent to atmosphere through either the flow guide valve or carbon canister (depending on the year). If you've capped all the vent hoses and are counting on the gas cap to vent that pressure, you're at risk of bulging your fuel tank or overpowering the float valves on your carbs and flooding your engine. Let's say you've got a quarter tank of gas and your car has been sitting in your cool garage overnight. Then you pull your car out of the garage on a summer morning and then drive it until hot and then park it in the 100 degree sun for the afternoon... Something's gotta give. You need a pressure release somewhere.

Not the kind of thing you do twice. Next time you're here, remind me to tell you a story about troubleshooting an ignition problem on my old Alfa... The Prince of Darkness taught me a lesson in a somewhat related way...

Are you sure that the big nut on the top of the strut shaft is tight? And are you sure the three nuts holding the top of the strut to the body are tight? I'm sure you already checked that stuff already, but somebody's gotta ask...

I also don't think there would be a problem. Stich weld if necessary. And as suggested... Don't clamp your ground wire onto the rotating portion. Clamp the ground onto the same side of the bearings the weld will be located so the welding current doesn't have to go through the balls. It's never good to send welding current through the balls.

I actually took measurements and have a sketch around here somewhere for that exact purpose. I've been in situations where I wanted to get a Z hatch open and didn't have keys (like on a parts car). I now know where to punch a small hole from the outside in order to hit the internal linkage to open the hatch. And the small hole would be easy to patch if necessary.

Excellent. One last thing before I bow out and let you get back to the real topic at hand. The KYB guys didn't talk much about the expansion chamber and why it's needed at all. My read on this is twofold: First, as the hydraulic oil heats up during use, it will expand. And if there isn't some provision for compliance somewhere in the system, the pressure could rise above a level suitable for the shaft seal (or worse). Second, as the shaft is compressed into the tube, the volume of the shaft itself displaces some oil, and that oil has to have someplace to go. If there wasn't a compressible volume in there somewhere, you could never press the shaft down at all since the internals would be "hydro-locked". So some answers to questions that you didn't ask, but it puzzled me a little at first when I saw the position of the floating piston change a little as they compressed the monotube. Figured maybe the same thing caught your eye. That changing position is due to the volume of the shock shaft as it enters and leaves the oil chamber.

Cool. I'm glad you were able to find NOS, and I'm hoping that it's not going to become the next part that will fail on all the fuel injected cars (like mine). I'm thinking your old valve is gunked up inside with crud and you might be able to clean it out and keep it around in case you need a spare. Failing that, are you gonna take it apart and see what went wrong?

Ummmm... Not even close.

Don't leave it the back of your hatch in the sun. The black fabric isn't very UV resistant. Kinda turns to dust after a year and tears when you look at it sideways... YMMV

Zedyone, I'm not a suspension guy, so my explanations come from the point of view of a non-expert who hasn't known this stuff forever. I apologize in advance if I'm telling you stuff that you already know. That said... Hard to press down is not necessarily an indication of damping. But neither is a slow or non-existent rise after being compressed. So when you say "there is little to nothing left in the way of gas pressure left. NO damping to be had in them", you're mixing somewhat unrelated functions together. The only thing that you can glean from a slow or non-existent rise after compression is that the gas has leaked out. You can't make any claims about the damping functions from that test. The gas pressure inside the shock has nothing (directly) to do with the damping. The only reason the gas is in there at all is to increase the static pressure on the hydraulic fluid which reduces the tendency of the oil to foam as it passes rapidly through the damping valve orifices under strenuous use. It's the oil that provides the damping, not the gas. Under non-strenuous conditions, the shock would work just fine with NO gas pressure in it at all (just like they did in the good old days). In fact, until or unless the oil starts to foam, there will be no difference in damping performance between a brand new gas-charged shock and one that's identical inside, but they forgot to put in the gas. Here's some good info from KYB that talks about the difference between the twin-tube (low pressure) and monotube (high pressure) designs and how the damping is accomplished: http://www.kyb.com/kyb-tv/the-differences-between-monotube-twin-tube-shocks/ http://www.kyb.com/knowledge-center/shock-tech-for-pros/monotube-vs-twintube/ http://www.kyb.com/kyb-tv/how-shocks-struts-wear/ Don't equate "hard to compress because it's got gas in it" with high damping. Don't equate "slow or won't rise after being compressed" with low damping. Those tests don't tell you anything about the damping, they just tell you how much gas you have left. Yes, if your shock is supposed to be gas charged and all of the gas has leaked out, it's not healthy like a new one, but assuming it's not worn out inside, it will still damp like a new one until you foam the oil. So, I'm certainly not telling you that you weren't due to change your strut inserts, but your old ones might still provide reasonable damping despite not being gas-charged anymore. Please forgive if you knew this stuff already. I worked on cars for many years and didn't... Here's hoping I wasn't the only one.

I second the mylar transparency suggestion. You should be able to find something at the craft store. I wouldn't cut it into strips though. I would try to find a sheet large enough such that you could wrap the whole thing into a full cone shape and stuff it down into the speedo hole to use as your ramp. This approach hasn't worked for me in the past, but it's been so long that I don't remember why. YMMV. And as for pulling the speedo out through the back... It's a hard "No". Doesn't come out that way.

No, and no. Sorry.

I have found the same thing. And that high of a gas pressure damps the spirits of those around me. Shocking, huh?

Back when I had my first Z, the fuel injection used to scare me. It doesn't scare me anymore. The only things that bothers me now are 1) The lack of visibility into what is going on inside the black box, and 2) the ability to do anything to change it. In my limited Z experience, I've found the performance of the carbs (once up to operating temp) to be about the same as the FI. The FI seems to be a lot more stable when cold, but other than that, I've not noticed a huge difference. I've found the fuel economy about the same as well. I don't have any insight into HC, NO, and CO though. The published belief was that the FI systems were put into operation as a result of continuing stringency of the emissions standards and even the open loop EFI systems we have might be better in that regard. I don't know... I do know that neither system work right unless you do it right and pay attention to all the little details. Personally, I'd love to have my Z on a dyno with the original EFI and then swap to SUs and run it again to see what happens. Of course, I'd also to toss on a pair of flat tops and run it a third time!

At the risk of being pedantic... Just because you can't press the shock down by hand doesn't really mean it'll be stiffer in application. Most of what you're doing by pressing it down on the bench is fighting the internal gas charge. You might not even be collapsing it quickly enough to get a real sense of the hydraulic valve damping. It's not the gas charge that does the damping, it's the oil. I'm no suspension guy, but it sounds like you're equating a high amount of gas pressure with a high amount of damping function, and I don't think you can legally do that.

So you're switching to carbs for this next engine build? Did you mention that before, or is this a new revelation? I've considered the same... I find beauty in the simplicity of operation.

Haha! It was for me! We can sure keep each other entertained! Worst part about it though is that Labatt's keeps all the better stuff for themselves up north. We get the Americanized versions.

I see what you did there.