Zed Head

You could also cut new threads a size smaller. But then you'll be the "idiot PO" if you ever sell the car. I would still do it if it was my car. Maybe even use standard thread size for stronger effect. I think that there's about 5 mm of extra stud when they're installed. You might not need the messed up part.

Yes, that does look like an R200. The rectangular piece of metal under the drain plug is one of the things I look at, along with the curvature of the bottom (of the diff). And the lack of a bolt-on side cover for the half shafts. What car is it from? No idea on what else to do while it's out, I've only swapped old diff for old diff, for ratio reasons. The side seals seem pretty easy to replace, from what I've seen. That thing is very greasy.

Bummer. It's still not clear though if the wires get hot when you're holding the key to Start, or if you let go of the key and the wires get hot. One implies that the starter just can't turn even though the solenoid is activated, the other implies that you have an electrical problem that keeps power to the solenoid after you let go of the key. The little yellow wire is where things start- it gets power when you turn the key to Start, which activates the solenoid, which pulls the internal piston in the solenoid down to press the relay button at the bottom of the solenoid cylinder, which then makes contact to provide power to the starter motor through that braided copper cable. The solenoid moves the gear in to the flywheel teeth AND is a relay for the starter motor. Think of that chain of events and maybe something will make sense. Measure some things with a voltmeter: key off, On, and at Start.

Looks right. My mistake, I didn't realize the alternator charge wire was in the picture. Also didn't read all of the previous posts. Did anything significant happen between Post #49 and #53? And what did you mean in Post #52? Something weird happened, you had the wires right before, why do you think that they're wrong now? When you say they get hot, do you mean when you turn the key to Start, all the time, or when the key is just On? And, if you mean when you use Start, do you hear a click from the solenoid first? Heat comes from current flow, and if you have current flowing but nothing's turning that would indicate something bound up. Or your battery is just too dead to turn the engine, but has enough juice to generate some heat. That's a possibility. Charge the battery and retry.

Show another picture of what you have now, including a better shot of the actual lugs on the solenoid that you're using,and a shot of the battery posts. Looks like you have things backwards in post #53, but it's not clear which of the cables is positive and which is negative. I hope you're not leaving the hot-to-touch wires connected for long.

.5 mm x 1.5 mm or 5 mm x 15 mm or 50 x 150?

Edit - deleted my "mean" sarcasm. You'll have to add more detail if you want some ideas.

Well then, either way, you don't have to worry about metal transfer on the points.

This is assuming that the mechanical/centrifugal, and vacuum advance are/were working. Have you checked timing while revving the engine?

Tomohawk has a 1978 with electronic ignition. I would guess that the capacitor is for absorbing electronic noise, similar to the alternator capacitor. Size probably not as important. Any old capacitor would probably do the job. Some multimeters have a capacitance measuring function (Fluke 115 for example). If you want to get a reading on the old one to match it. Even though it may not matter much. edit - Tomohawk, aren't you using Pertronix?

It's the same as the common potentiometer installation (isn't a two terminal connection more properly called a rheostat?). Seat of the pants or an air-fuel ratio (AFR) gauge or nose are the ways to measure effect. It changes the response curve across the complete range of conditions, I believe. If you want to change the idle AFR only, it would be be better to use the idle air screw on the side of the AFM. That's the one where a "sniffer" is recommended, by the FSM instructions.

Surprising that that is still a problem. Most modern electronic modules are designed to remove this issue. Also surprising that Pertronix doesn't have an add-on solution. Maybe that's where some of the Pertronix failures come from. You could run the output through a GM HEI module and let the HEI control the coil. Module triggering module. The HEI module doesn't put full current through the coil unless the engine is running. It would be kind of goofy but I think that it would work. $25.

If you're on the Oregon side of WA ST. there are a couple of 240Z's in the local salvage yard.

I didn't look at the wiring diagram but if the running lights switch is on the circuit that could be your drop. It's combined with the headlight switch, in the same box on top of the steering column. Does the top of the shell behind the steering well get hot when the lights are on?

The relay you bought should work, if that's what you need. The Ford relay is popular because someone that knows a lot used it and described it and likes it. And, apparently, it triggers at a fairly low voltage, which is good. They both work the same way. The test I described will show you if the relay offers anything though. If jumping the solenoid directly to the battery doesn't solve the problem then the relay won't work either.

I've always left the mustache bar in, never actually left it attached to the diff, only seen it done that way. Thought it was worth mentioning. As madkaw says, the diff will hang from the two studs in the bar without the nuts, giving time to practice lifting and moving it before bumping it forward it and letting it down. I've also found that the inner half shaft nuts can be removed using a bunch of extensions on a ratchet handle, working from the wheel well, if you rotate the shaft to the right spot. Leave the outer nuts for last so that you can use the wheel to rotate the shaft. Also, the half-shaft flange can be a tight press fit on its locating center. You might need a punch or chisel to knock it loose, on the inner and outer sides both. If you use a chisel to split it, make sure that you don't leave any burrs on the surfaces when you put it back together. In principle, it's pretty simple but there are few spots that you can get stuck at.

Sounds like the ignition switch works correctly but the solenoid may not be getting enough current to make and hold the contact. I don't know if there are multiple contacts in the switch or just one that splits though. You could remove the small wire from the starter solenoid and attach a jumper. Take other end of the jumper and touch it to the battery positive post (basically a home-made remote starter). That should activate only the starter solenoid and the starter. That will take all of the wiring and relays out of the picture and focus only on the solenoid and starter. If it works correctly, the problem is somewhere in the wiring and relays/switches. If not the problem is still at the solenoid and starter. Make sure the car's not in gear when you do that, since you won't have a foot on the clutch pedal or know where the shift lever is. People have run over their own feet doing this.

Have you checked your flexible lines? The ones that run from the body to the suspension. You might have one about to blow. Expanding when pressure's applied, contracting when released. Might need help to watch while the pedal is pressed.

The other typical switches are for top gear and neutral. Most are normally open and close when the condition occurs. An ohm-meter should tell the story. Wouldn't mind seeing a picture of the plastic collar if you haven't tossed it yet.

When I installed the HEI module on my 76 car, I left all of the wires to the coil and ballast connected. I only disconnected the two trigger wires from the distributor, and the factory module in the cabin. I used two jumper wires directly from the coil posts. A jumper from the coil positive to the B terminal, and a wire from the coil negative terminal to the C terminal. The two wires from the distributor, a green and a red, were connected green to G and red to W. If you have two blue wires from your distributor, you'll probably find that they are spliced to green and red inside the distributor. If you connect them backwards it won't hurt anything but your timing will be retarded and jumpy. If you find that just swap them. I also ran a separate wire from the wide mounting grommet on the HEI module to a verified good ground. If you're positive that the screw through the mounting hole is a good ground that would be unnecessary. Eventually I removed the ballast and made other modifications but that setup worked fine for quite a while. On your 78, you can do the same thing, the absence of the ballast won't matter. It's all about coil power control.

My mistake, thanks for the correction. I wish they had extended the fuel cut to a lower RPM. I think that's a big part of why these cars tend to be gassy smelling. 3200 RPM is pretty high, even 2800 is. Regualr driving gives no fuel cut most of the time. My 95 Pathfinder, apparently, cuts fuel when the throttle is shut at any RPM if moving. They learned. p.s. to my other post - My BCDD and TPS both check out. I think that my AFM is a little bit funky and has an uneven enrichment curve. Not super relevant to the OP's problem. Enough about my car...

A 5 is actually a hotter plug than Nissan recommended. Not sure why NGK would show differently. For many short trips where the engine might not heat up completely a 5 would be good. Extended freeway or constant speed trips (normal driving) a 6 might be better. 7 would be for extended trips with expected high engine temperatures and high loads, or racing.

What RPM are you talking about while decelerating? The ECU also has a fuel cut function, from 3200 to 2800 RPM on the way down. Page EF-12. The BCDD's purpose is HC reduction (EC-5). Not idle control. It's not clear how though, the FSM just says it's for "maintaining manifold vacuum at the proper operating pressure". Maybe to provide extra air to allow proper burning of any fuel injected. Implied by the word "operating" in the FSM description. I'm glad this came up because I've been catching one sharp whiff of unburned fuel right as I stop. Noticeable since it's warm now and the windows are down. Off to check the BCDD... Edit - just realized what that one connector with the plug in it is for, up by the coil. It's the BCDD, and maybe other, "function test connector". Looks like a pain. Edit 2 - the instructions in the FSM for checking the BCDD are confusing. Check resistance and voltage on the same circuit at the same time. Might take more thinking. Edit 3 - I think that instructions in the FSM for the BCDD are incorrect up to 1978 (says that 0 volts is good for everything - incorrect). The 1979 FSM has a whole new test procedure with new diagrams and a chart. That makes sense.

Didn't realize they'd go bad so quickly. He didn't give any gory destruction details. I've replaced mine several times using jack stands on the rear only. They're heavy so if you used an auto lift you better be able to maneuver about eighty pounds over your head easily, or have a transmission jack. Doesn't sound like a whole lot but it's an awkward load. On the ground on jack stands you can either bench press it or use a floor jack, balancing carefully. I've always used a floor jack for ease and to stay less greasy, plus it makes it a one man job. There are basically two ways to do it, leave the mustache bar on and it will drop straight down and go straight back up, or wiggle it forward to release the studs from the mustache bar, and reverse that to install.

I think that the bigger gap came when they went to a better ignition system. They got rid of the ballast resistor, changed the coil, and most likely improved the internals of the ignition module to take the higher current. This apparently gave enough juice to open the gap. A guess.