Captain Obvious

You don't have to unload the suspension when you loosen those bolts. In theory, you can leave it on the ground and loosen them. The inner rubber of the bushing should spin to it's neutral point once the bolt head is loose. Of course, this assumes you can actually fit enough of yourself under there to loosen and re-tighten those bolts with the car on the ground. I don't remember exactly what I did... It think it may have involved rolly dollies on wheels.

I believe the importance of getting the float level-ish is to prevent it from hitting the underside of the lid. Here's a description of the problem I've had. This is what was happening that made me add some weight. Level is too low, adjust the tang. Level is still too low, adjust the tang some more. Level is still too low, adjust the tang some more. Bam! Carb overflows. At that point, the float is probably hitting the underside of the lid, or maybe even or the inside of the bowl if the angle is extreme enough.

I'm no radio expert, but I believe the purpose of that capacitor is a filter to only allow signals through in the range that the radio cares about. It also blocks any DC voltages, so you won't ever be able to shock yourself by grabbing the antenna or some other strange fault like that. You could put that filter either in the plug (as they have), or inside the radio case, but the sooner you get rid of the stuff you don't want (noise), the better. That's my take.

So you have like three quarters of an inch less toe just by changing the inner bushings? Am I interpreting that right? If so... Wow. Can you take some more pics of the bushings you took out. Shadows in the pic you posted above are making it look like there's some real weird stuff going on with them. Might just be light, or might help explain what was going on? And lastly... You did remember to leave the big bushing bolts loose until the suspension was loaded, didn't you?

So my inserts were made on a lathe (because I have a lathe and I'm not afraid to use it), but you could probably find something store bought that would perform the same task. My thoughts on that are... Brass has higher density than steel. And steel has higher density than aluminum. I used brass because it was the highest "bang for the buck" in the density department meaning that the insert could be made smaller to get the highest mass (as compared to steel and aluminum). If for some future reason, the ballasts I put in there are deemed too heavy, I can switch out to steel or aluminum in the future to lighten them up. I'd be happy to talk on the phone about your frustrations. If you want, send me a PM and we'll do some of that. I feel your pain.

My thoughts? I spent a bunch more time trying to get the 72 floats to work without adding weight and I failed. Nothing I tried could get them to work, so I added weight. Again. Here's some pics of my latest incarnation. This time I made a threaded insert so I could change the weight in the future if necessary:

Me too. I mean, I've only done two sets, but the old used ones I took out looked good enough that I think they could be re-used if really necessary. Steve's look hammered!

Yes, the pivot points are different between the two lids. And the mounting surface depth for the float valves into the lids is different too. I took a bunch of measurements of the lids a while ago an think I posted some details. And about the bent float hinges, I'm wondering of the severe bending of your hinges was done by ZT in order to get them to work right. They shouldn't be like that, but that might be the only way they could get it to work? Ideally, here's what you want your float to look like when the level is correct: And absolutely check the float levels wet. If the levels are OK, then you're done. if not, use the wet set method to get them right. You can't just measure them dry and assume that's good to go.

Wow. That's way cheaper than I would have predicted. Did he supply the stock material as well? Cut them out to shape? Looking at the pics, it appears to be black and red sick screening on a white plastic substrate? Are they thicker than the originals?

Actually it doesn't matter which side the force comes from. If it's not supported correctly, you run the risk of bending something. And you're not really "pulling", you're just pushing on the other side. In order to PULL it, you would need to put the bushing shell in tension, and you're not. So pedantic aside... The bottom line is you are correct. You need to support the correct area and press in a normal direction in the correct different area.

That should be fine. I got zoom on my screen.

Wait... Poly everywhere? I sure hope you can still get some rubber stuff.

Well I'm not claiming to be qualified to check anyone's work, but I have a couple comments... First, the metal portions of those floats looks like they have bent away from the floaty portion of the float. And one of them worse than the other. From what I've seen, the metal hinge part of the float should be pretty much parallel to the top of the float foam portion. Yours look like they have been pulled away from the foam. Second, you are working on a pair of three screw round tops and they were designed to operate with different float levels in front and rear. So if you mechanically set both floats the same distance from the underside of the lid, I'm not positive that's going to translate to the same level once they are wet in the car. The other changes may come out in the wash, might not. And last, don't forget that the mechanical set you did there is just to get them in the ballpark. A wet set with a clear tube is the way to confirm that the levels are correct. Any mechanical means is just a preliminary ballpark setting that must be confirmed wet.

So I assume from the banter about burning out the mustache bushing... I'm assuming you're putting poly in the old shells? And if you've got the hydraulic press, dealing with the outer rear bushings isn't that difficult either. Getting something fixtured square and supported correctly underneath is always the hardest part. In other words, once your sure you are getting all the force on the correct parts and in the correct direction, the rest is usually easy.

Now that's cool. You had those silk screened? That couldn't have been cheap.

Haha!! Trust me... It'll be worth it. The video will help a lot of people understand what's going on.

Naaa. A trace on a scope just wouldn't have the same impact as watching the needle swing. I think seeing the needle swing with the current switching would give the best sense of what is going on. I think that would convey the concept the best. I'm not sure I have an analog meter around here anymore either. I'll take a look, but I don't think so.

Yup. It would be cool to run that test again using an analog ammeter in series with the gauge. That way, you would be able to see a better representation of the PWM regulator current.

Datsun put one regulator device in each of the gauge cases. So the TEMP/OIL gauge has one regulator that is in series with both of the needle moving heating strips, while the FUEL gauge has it's own regulator. Note that the AMP and VOLT gauges do not use a regulator because they do not use a heated bi-metallic strip to move the needle. The AMP and VOLT gauges use a D’Arsonval permanent magnet method instead of the heated strip, and hence do not need a regulator. So the TEMP/OIL gauge "can" contains one regulator shared (in series with) by both of the meters, and if that regulator develops a problem, that problem will show up in both gauges. As for what may be happening... If the shared regulator has dirty contacts and isn't making good contact, both gauges drop to zero at the same time. Note that the problem may be in the incoming power wiring and not the regulator at all, but based on the cyclical nature of the issue, I suspect the regulator. When it's stone cold, key just turned to ON, the regulator strip will be it's coldest and the pressure on it's contacts will be at it's greatest. Once that strip warms up and the system moves closer to equilibrium (PWM equilibrium), the contact pressure will decrease. I'm thinking when it's stone cold, the higher contact pressure makes a contact, but once it warms up and the contact pressure decreases, it goes intermittent. Of course, troubleshooting electrical stuff over the interwebs is never an exact science. But that's my read from a distance.

I just pulled the gauge theory stuff together in a standalone thread: https://www.classiczcars.com/forums/topic/67803-how-the-gauges-work/ Have a nagging suspicion that I did that already some time before, but couldn't find anything?

Here's a pic of one of the gauges. You can see the two different heating coils wrapped around two different "U" shaped bimetallic strips. Interesting to note that internets research indicates that "U" shape is part of the compensation as well. The concept is that the unheated side will compensate some for changes in ambient temperature. "They say" it doesn't get rid of all of the temperature based effects, but it helps some. Between that "U" shape and the compensation stage, the gauges seem to be really stable. So this is an example of the compensated gauge with the two stages: And here's a closer-upper pic of the compensation stage showing it's parts: The switch opens and closes to keep the temperature of the compensation strip at a constant temperature (ave). If you put a Voltmeter on the sender unit, you'll see that it isn't a steady voltage, but is instead a square wave.

So the basic gauge system described above works, but there are inaccuracies caused by ambient temperature (cold day vs. hot day), and variations caused by system voltage (low alternator output voltage vs. higher alternator output voltage. In order to compensate for those real world conditions, the gauges are a little more complicated than the simple system described above. There are two "stages" to the compensated gauge. One of those stages is he simple gauge we already talked about above. The other stage is the compensating or regulating stage. It's job is to compensate for changes in ambient temperature and varying system voltage. The compensation stage consists of another heating coil wrapped around another bimetallic strip. This bimetallic strip forms an electrical switch such that when the strip heats up, it breaks contact. And when it cools down, it re-establishes contact. The trick is, that it makes and breaks contact to it's own power source and the power source for the simple gauge stage. The result is that this second strip/heating coil combo will make and break the power source such that it will always achieve the same average temperature. Of course the temperature is rising and falling some, making and breaking connection, but the AVERAGE is always the same. Colder day? Power to the compensation strip will have to be on longer to reach the temp that bends the strip to the point where it breaks the switch connection. Hot day? Just the opposite. Power will be on for a shorter time. Low system voltage? Again, power will have to be connected longer in order to heat the strip to the desired temperature,. And conversely, if the voltage is higher, it'll take less time. The result is that the compensation stage creates an ON/OFF/ON/OFF pulse train whose duty cycle and frequency will change depending on the ambient temperature and system voltage. This effectively creates a voltage source that will always supply a constant amount of POWER to the gauge system under all conditions. Clear as mud? Connect that constant power source to the simple gauge from above, and you have this: If you put your key in and turn it to "ON" you should see the gauges start to rise. Don't start the car. Just pick a needle and watch carefully. You'll see the needle start to rise, but probably before it reaches it's final position, it'll pause... Then start rising again. Then pause again. This will continue until it finally reaches it's final position. And even then, if you watch carefully, you'll see the needle actually wiggles a tiny bit. This effect can most easily be seen with a needle that's moving well above minimum like a full tank of gas. That pausing and wiggling is the compensation stage opening and closing.

Many moons ago I promised to describe how the gauges work... So in order to understand how the gauge system works, I think it would be a little easier to first understand how they DON'T work. I think everyone already has a good handle on this simple system, but it's an important place to start. Here's a pic of a simple (uncompensated) gauge design. Wrap a heating coil around a bimetallic strip and mechanically attach that strip to the linkage of a gauge needle. Flow current through that heating coil and to a sender unit who's resistance reflects the level of whatever you're trying to measure (temp, oil, fuel, whatever). As the resistance of the sender unit changes, the current through the heating coil changes and that changes how hot the bi-metallic strip gets. The lower the sender resistance, the higher the current. The higher the current, the hotter the bimetallic strip gets The hotter the strip, the more the needle moves. Here's a pic: This simple uncompensated gauge system does "work", but it is subject to a few real-world outside influences that can affect the accuracy: First, since the whole thing works on the temperature of the bimetallic strip, the gauge will read differently on a hot day than on a cold day. And second, since the gauges are powered by the battery system of the car, changes in that system voltage will affect the gauge readings. The gauges would read differently sitting with the engine off than they would with the engine spinning at 3000 RPM when the alternator has kicked up the voltage a bunch. The system voltage can vary from about 12V to over 14V and the gauge readings would change as the voltage varied. So the basic gauge system above sorta works, but these two real-wold effects are undesirable. If the above basic gauge system makes sense, I'll get into how they compensate for those two real-world effects.

https://www.classiczcars.com/forums/topic/64427-no-oil-pressure-after-rebuild/#comment-607221

Yeah, you and every other Z owner who didn't buy it new. Figuring out what previous owners did do, didn't do, and/or screwed up... It's a sport.