Captain Obvious

The manual says it exists to prevent hysteresis in the advance mechanisms. No idea... Makes me think they were having some small issue in the field and management went to the engineering department and said "Don't care how, but fix it". No idea if there really was a problem, but that's what it smells like to me.

Wait!! I knew you looked familiar!! You're D-Day, right? You almost ran over me one night while I was playing guitar on the stairs!

I believe that is the "contactor". We discussed it some in this thread a number of years ago: https://www.classiczcars.com/forums/topic/42650-distributor-question-the-contactor/?tab=comments#comment-384319 Unfortunately the pics are gone, but I can reload them if it would help. I don't know if the page numbers are the same in everyone's FSM, but in mine, the contactor get's mentioned on pages EE-25 and EE-26.

kinser, Thanks for the gauge details. I had found the datasheet, but didn't see that gauge mechanics document. It looks identical in theory of operation to the one I have. If it works as well as mine, you're gonna love it. So it sounds like the car is running well enough to drive it now? That's a great improvement from when you started! Your next task... Clean some electrical connections and double/triple check for vacuum leaks. It's likely you have several small leaks throughout the system.

Oh. I was going from the text above when the OP said "At this point I felt the fuel pump was too much for the car and we pulled it and replaced it with a Delphi stock replacement." and "With the stock pump replacement, the fuel pressure still seems a little high but not as high as with the previous pump." I didn't have time to sit and wait for all the videos to load and run calculations on multiple gauges and stuff. I was just going off the text and assumed there was a reduction in fuel pressure with the stock style pump.

I take the tank off my motorcycle every year for winter storage. Drain it completely and then (on a nice sunny dry fall day), let it outside in the sun to dry for the day. Once it's completely dry inside, I put it in the basement where there is a dehumidifier. Doesn't rust if you keep the humidity low with the dehumidifier.

Well for twenty-five bucks, it's certainly worth a shot. If it works as well as mine, it'll answer any questions about the real pressure that the injectors actually see. I took a quick look at Ashcroft's website and I couldn't find a diagram that explained the basic theory of operation for the internals. I did see some mention of magnet(s), so I assume it's the same magnetically coupled meter movement concept as the one I have, but I couldn't 100% determine. This whole thing sounds like a typical 280Z story to me. Most of us have been through it. So far, you made a simple mistake and screwed up your ignition timing and vacuum hose routing, Your PO put in a fuel pump that was incompatible with the stock pressure regulator. And you paid for an injector cleaning that had to be done twice because the first time didn't work out as intended. Nothing unusual so far. Admiral goal to keep that sort of stuff from happening to anyone else, but I wonder if you're trying to prevent the un-preventable.

I didn't dig into the specs of that Ashcroft differential gauge, but the biggest thing you would have to watch for is something compatible with gasoline. The Orange Research gauge I have is all metal body and piston and has Teflon seals. It also magnetically couples the internal piston to the meter movement so the gas never gets to the needle. It's completely segregated. I don't know anything about the Ashcroft, but if it can handle the gasoline, then it should work fine. I don't remember what I spent on mine, but its very convenient having it at my disposal. No math. No units conversions. Direct reading.

Haha!!! "Never do this." I understand completely!

Haha!! Looks like something out of Tron. He better be careful going out like that or he might get uhhh... shot - key? I'll be here all night, folks. Seriously. Where else am I gonna go?

Thanks for the info guys. Maybe next engine I overhaul will get a similar treatment.

Here's the theory for the differential pressure gauge I have. It's essentially just a piston (which also happens to be a magnet) sliding back and forth in a tube. That magnetic piston is coupled to the gauge needle so there is no process fluids (whatever you are measuring) in the meter movement area. Operates like this: And this is hooked up to the car. Too big to leave in there all the time, but it's fantastic for diagnostic purposes. One side pushes while the other side pulls. The pressure reading would go down if you disconnect the vacuum side because that side isn't pulling:

They didn't bond the neutral. The full alternator output is Line to Line in a 3-phase "Y" configuration and for normal stuff, you don't need it at all. Just run full wave rectification between all the L-L and the neutral is unnecessary for the 12V alternator output. One side of the six diodes becomes ground and the other becomes alternator output. No neutral needed. However, they brought the neutral out to supply a couple things like the brake check relay and the voltage regulator. Not sure why they did that instead of just using the full output, but that's what they did. For some reason, they thought using Line to Neutral was a more reliable indication that the engine was running and the alternator was turning and working. Maybe it has to do with losing one phase or something? Someone here with more 3-phase experience could maybe provide input? How's that for a thread diversion?

All that said, I'm intrigued by the reduction in valve mass. I don't know what a typical valve weighs, but you mentioned that you took off 2g of material. What is that in percentage of total? Anything significant? And if so, are there any performance gains possible from such a change? (Thinking less valve float at high RPM for example due to the reduced momentum?) I'm beyond my pay grade with evaluations like that, but it seems possible. Have you experience that deep with engine details?

I bought a differential pressure gauge. Hook one side to the fuel rail. Hook the other side to the intake manifold. My fuel pressure "seemed" like it was all over the place, but when measured differentially (as you really should), it was rock steady at 36psi even when you goosed the throttle. It's really deceptive when just measuring one side. So why doesn't everyone do that? Because they're expensive and delicate. I got lucky and found one on ebay for cheap. I'll post a pic when I get a chance.

Could be a grounding issue or a faulty proportioning valve. Or a faulty parking brake switch. Why does it look like it's only lighting up half the "BRAKE" letters on the speedo? Like light is bleeding through from the left side. Or the bulb isn't inserted into the hole in the back of the speedo completely? Even if it's dim, I would expect it to light up the whole "BRAKE" indicator evenly. Have you stuck a hand up there behind the speedo and gently wiggled stuff around to see what happens?

You are not wrong. In the original system, the brake check relay is designed to pull in at a voltage less than full alternator output. It is connected to the "N" terminal* of the alternator which should supply a voltage of alternator output divided by the square root of three, or approx. Alternator output / 1.73. So I'm not surprised that your original relay went all crispy when you powered it from the full alternator output. Probably lasted for a little while, started to smell a little, and then went open circuit? And yes... It sounds like a simple solution would be to use a relay that can handle the full alternator output (12-15 volts) on the coil all day long. * For those who care, the "N" terminal is actually the neutral terminal from the three phase generator that is the alternator. And because of the three phase voltage, the L-L voltage is 1.73 times the L-N voltage. Conversely, the L-N voltage ("N" terminal) is L-L voltage divided by 1.73

And don't get me wrong... I'm not poo-pooing the work. I think it looks cool. And it would certainly be on the "build sheet" of things to tell people about the motor. Would look great on the mods list if the car is ever sold (but let's hope that doesn't happen. )

Oh. In that case, forget about what I said. If it's still glowing even with the dash lights completely off, it's not light bleed.

Haha!!! I didn't know Atlanta was Coke's main hive. Kinda like parking your Nissan in GM's lot, huh? Looking forward to seeing the HVAC stuff Wayne. Should I bring anything from my end to help out? Give me a call if there's something I need to bring along.

My guess would be that there is nothing electrical wrong with your e-brake light. There is a little rubber shroud inside the speedo that is supposed to separate the e-brake light from the dash illumination lighting, and I suspect what you're seeing in your e-brake light is bleed over from your dash illumination bulbs. The rubber shroud gets dry and brittle over time and maybe yours has deteriorated to the point where it's not sealing properly and it's allowing light to get where it doesn't belong. That combined with the fact that your speedo lights are very very very very very cornea burning bright.... So... Does the e-brake light glow go away when you turn off the dash illumination bulbs?

My honest opinion is that you're working in the minutia. I don't think there's any meaningful performance benefit to what you did to the valves. Looks pretty? Certainly. Bragging rights? Absolutely! Performance gains? I would have to see the dyno sheet before and after. I'm no engine builder, but I think there are waaaay bigger fish to fry before you start seeing any changes from the surface finish on the valves. Cam changes. Intake tract improvements. Combustion chamber design improvements. Exhaust tract improvements. All that stuff. I think the valves are in the .1% at the very end once everything else has been optimize. The NASCAR and Indy guys who have already squeezed out the other 99.9% elsewhere might see a tiny improvement, but not us. That's my uneducated non-expert read.

So what's the bottom line? It sounds much better. Are you calling this a success now? The thread was about severe driving problems. Are you claiming victory? That would be sweet!

You better. I'm going back into mine this off season.

LOL. MacGyver is still looking over his shoulder after all this. So the tubes on the small engine two-cycle thing... One is supply from the tank to the carb, and the other is the return from the carb back to the tank. The system operates just like the Z. The fuel pump pulls more then necessary from the tank, some of it is used by the carb, and the excess is pushed back into the tank. Continuously circulating. And the closed system operating under a slight vacuum is what allows it to be used in any position without spillage. Like chain saws. And as the fuel is used up, the duck--bill valve on the cap allows air into the tank to replace volume of consumed fuel. I've had that duck-bill check valve plug up on some of my small engine stuff and what happened to me is it runs great for a little while and then will stall and not restart. Too much of a vacuum in the tank and the fuel pump can't pull fuel out anymore. Loosen the cap and it'll run for a little bit and then quit again. So a little vacuum is good, but too much vacuum will starve the engine lean. I don't know why your clogged tank valve resulted in a puddle of fuel. (And it still bugs me. )