Zed Head

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.

Wouldn't it be much easier to just put some fluid in to the diff that's in the car now?

It might be a multilayer construction. Fluroelastomer on the inside for chemical/oil resistance and cost, silicone on the outside for strength and durability. Multilayer is how fuel line is made, if you get gasoline on the outside of your fuel hose you'll see that it really doesn't like it and will get soft and a little gooey, and bleed black material on to your hands. There was a pretty good discussion on zcar.com about this a month or two ago.

Datsun 280Z Fuel Tank L28E (From Jul.-'76) Nissan Parts, NISMO and Nissan Accessories - Courtesyparts.com

All I hear at 1:10 - 1:20, besides the engine, is beeping. Your first video had more weird noise.

Any chance you have a head bolt or two bottoming out? Torque wrench working incorrectly? Dry bolt threads giving high torque wrench readings? Warped head?

You got me. I just went out and checked a replacement plug I got at a hardware store and it was 22 mm. I always use my big crescent wrench, so never really knew.

One year is not much. But, with the plugs out, you could probably get it to turn with the average length ratchet handle. Or, if you have room, you could put the transmission in to high gear and push the car to turn the engine. 22 seems big. Probably in the 14 to 17 range.

You meant half of a millimeter, right? Not half an inch. And the groove should be on the cam shaft retaining plate, matching a notch in the sprocket. The groove doesn't move, but the notch of the sprocket does. Make sure the engine was being turned the correct way when setting TDC. Otherwise you can get slack in the chain and the mark won't be where it would be when the engine is running. "After adjustment" is close to where you want to be.

A slipping clutch generates lots of heat, enough to destroy the flywheel. Crawling to the shop while it slips might not be a good idea.

Second on checking for pressure build-up. That will narrow it down. Take a piece of hose of the size of the bleeder and run it in to a container to avoid spraying. It seems unlikely that it's mechanical unless your brake pads are so thick that they barely fit between the caliper and rotor and bind when everything expands. Even then, clearance should get looser, not tighter, unless the rotor steel expands more than the caliper steel. I think that you can have pressure build-up in only the front system since the reservoirs are separate. You might just have a bad MC. Maybe it was assembled incorrectly. Maybe there's debris in the return port acting like a check valve.

Actually, I think that timing at 4,000 RPM would tell something. If you know your advance curve, and disconnect the vacuum advance, you could calculate initial. And with a good light I think that you can get timing just from cranking. Or a better way to guesstimate initial timing is to look at where the points open, or the rotor passes the pickup coil or the led gets blocked (or unblocked), rather than distributor rotor position. That doesn't tell anything about timing, since the it doesn't tell where the distributor body is positioned. When you have no clue, you can't rule anything out is the essence of my post. Things should be more clear after 87 posts than "revving to 4,000 RPM is the only way to to keep it going". What good will a vacuum reading at 4,000 RPM be? No offense intended but a methodical approach would help get to a solution. Get good solid basic information and a path will become clear. This thread is jumping all over the place.

You didn't mention what the timing light showed. Just for the record.

Grab a tool, of any kind, open the hood and go loosen one screw, bolt or nut that will need to be removed to fix any one of the problems that you know of. If you find yourself an hour later with most of what you're working on disassembled, keep the car. If you can't even get the motivation to turn one bolt, sell the car.

I took your thread title literally, so described how it's supposed to work. The FSM description should help, attached. It shouldn't work like your describing yours as working.

Yes, it would be from an exhaust valve not opening completely. Pressure pops back through the intake valve in to the manifold. It might not be that at all, hard to tell from the video. You'd probably hear more noise all the time, so maybe not. On a carbureted V8 you'll actually see fumes coming out of the carburetor when it happens. The other possibility is knocking (detonation) from timing too advanced or from low octane gas. Again, just possibilities that sound somewhat like the noise on the video. I don't know what SeaFoam does to the octane rating of gasoline. Timing too advanced could be from a stuck advance plate in the distributor. That might be more sporadic. These are all just guesses. You might just check timing first, rev the engine while checking and make sure it doesn't stay advanced when the throttle is back at idle.

If you mean that noise that sounds like popping inside the intake manifold, you might check your valve lash settings again. One of them might have loosened up. It sounds like other engines I've heard with a bad cam lobe (common on small block chevys), but in your case maybe just a valve that's not opening completely because the lock nut has backed off and the pivot screwed itself in. Easy to check.

The AAR should have power supplied to the internal heater as long as the engine is running. It's on the same circuit as the fuel pump, I believe. So it should only cool down when the engine is not running. If your idle stays high at a light, it's most likely not the AAR causing it.

madkaw touches on another possibility, or maybe is referring indirectly. Maybe your timing is just off. Too many posts to go back and see if it's been verified. By the way, my post #64 was in reference to Steve's post #62. Although, it could apply to anyone looking to avoid all of the module and coil resistance matching stuff.