Zed Head

A dead tach could be a problem also. If it is shorted out it might be hindering the "break" part of the make-it-break-it spark generation cycle, since it's connected to the coil negative terminal. Has it always been that way? Yes, the module is up in front of the fuse panel. The parts on the 280Z EFI cars are interconnected. Problems with one system can cause problems with another. You might have some troubleshooting ahead of you.

That's a brand new thing. Looks like somebody at MSA came up with it. You raise a good point about the rubber. It looks like the part you have will dramatically increase travel before bottoming out. Not sure it's meant for just a one or two inch lowering. Too bad they didn't add adjustability. You're kind of on your own. No offense but I'm not seeing a big benefit to that part. I've not seen many people at all complaining about bottoming out after using lowering springs. To be blunt, I'd return them if you can. I think that they're meant for the "slammed" cars, not Eibach lowering springs. I'm surprised that MSA advertises them the way they do. Kind of worrisome. People don't really have that problem.

Post a link to the parts page. Never seen those parts before. Also, not clear what car you're working with.

The fact that it starts easily by push starting kind of suggests weak spark. Could be poor current flow through the coil and ignition module. You need high current to generate a good spark when the module cuts it. The low voltage during starting won't help. There's a color wiring diagram in the Downloads area. You could trace the path and check the likely spots for resistance/crud. Clean up the path for power to the coil and on to the module where it's grounded. 78 has the plug-in module, maybe remove it and clean it with some contact cleaner like Deoxit. Might also be that your coil and ignition module are just getting old.

I think that the process is described Honsowetz's or Monroe's book, or both. I've thought that torque plate would be best for machining. It would take some ingenuity, maybe counterboring or even threading the bolt holes. But then you could flatten it via bolt torque to the top surface and skim just the odd high spots on the mating surface. When it's bolted on to the block it will be the same as on the torque plate.

I got curious about the need to shave or skim the head if it was out of spec. for flatness. My head was at the limit, bowed up in the middle, so I put it back on with no head gasket and tightened it back down to see how much it would take to make it flat again. It didn't take much to close the gap. I'm pretty sure that the How to Rebuild book uses a wider range also, I seem to recall .007", not the .004" that Nissan uses. The resurfacing has always bothered me because it leaves the valve train spec'ed to a different surface than the bottom of the head after skimming. The valve train is still warped. But if you tighten it back to flat using bolts then the valve train should straighten out also. Just a thought.

You can make your own tool from a piece of wood. Not much to them. Head gasket seems most likely. I haven't seen much about cracked heads, especially the later years. But, it's usually overheating that causes the HG to leak, which also causes the head to warp. But, also, I found that it really doesn't take much force to bend the head. You can "reflatten" it with a single head bolt and a short wrench.

He's using the same picture for both pumps, which he borrowed from Rockauto or some other site, or Airtex themselves. So you don't really know which pump you're getting. He might be selling the $30 pump for $67.50. I'd call and ask for the brand and where he gets them before buying. https://www.rockauto.com/en/moreinfo.php?pk=60014&cc=1209260&jsn=364 https://www.rockauto.com/en/moreinfo.php?pk=60014&cc=1209260&jsn=364

I think that they reduce the odds of leaks. Maybe also strengthen the seal for when you bump the bottom of the pan on something.

If stopped working means it just quivers and jumps or it doesn't read right, that sounds like the ignition module. They go bad often these days after 40+ years.

I was going to mention that you don't have to be exact on the rotations. For example, in first gear you'll have 3.592, 3.321, or 3.062, for example. 3.592 is between 3 1/2 and 3 3/4, 3.321 is between 3 1/4 and 3 1/2, 3.062 is almost right on 3.0, for one complete turn of the output shaft. Set your tail shaft indicator straight up, estimate the turns to get a full rotation and see what you get. The 1/4 turns are easy to eyeball. Once you look at the possibilities and try a few counts you'll say "it has to be ____".

Aren't you missing the reinforcing plates on the edges? Maybe they got rid of them with the F54 block. http://www.carpartsmanual.com/datsun/Z-1969-1978/engine-280z/cylinder-block

Forgot to say, you could put a little indicator on the tailshaft that's easy to see. Turn the input shaft 3.6 turns and you should see one rev on the back.

Looks like the 620 has the 240Z ratios, doesn't it? Better measure the length. It might be shorter. Leader...that's a good one. Just 'cause you're in the driver's seat doesn't mean you know where you're going. Especially with a whole car full of backseat drivers.

I've had good luck looking through the fill and drain plugs at the synchro and coupler sleeve teeth. I think it's third gear. They should be sharp and symmetrical. Rounded teeth is a sign of abuse.

It's your money and time. Cheaper than the wrecking yard. Good luck.

The ad says the brand is "Martin" and the eBay store is Martin's auto parts. Looks like he's selling cheap Asia knockoffs. $30 + $65 = what I paid back in 2009 for an Airtex. My Airtex pump has lasted probably 40,000 miles or more, still works great. So $65 for a known quantity (IF the zcardepot pump is an Airtex) or $30 for a mystery pump.

Eurodat and Dave WM have both been deep in to the 5 speeds. Seems to me that most of the parts are available so as long as the adapter plate bearings haven't blown up, which they do sometimes, and the gear cones, for the brass synchro to ride on, aren't rusted or worn out, it should be rebuildable. Another common wear area is the nose of the input shaft, if somebody let the pilot bushing go bad. The tail shaft housings tend to get chipped from dropping also. The "snout" of the front cover, that the throwout bearing rides on, can get pretty worn. They've been known to break off if very worn. The output shaft bushing, in the back case, can get very worn also. Some of the guys have found a fix for that problem. I bought a mystery 5 speed that turned out to be destroyed inside. It went in to each gear when I was looking at it but once it got spinning on the end of a motor it started crunching. I thought it might have problems though so I tested it in the garage. I only paid $50 for it and used the front case for a 71C swap. That story probably doesn't make you more confident. The drain plug magnet will tell a story. If it's been freshly cleaned, that's a concern. @EuroDat @Dave WM

Any chance your bulbs are just burned out? It seems like you've tested the circuit from end to end. One thing that can happen when testing using a meter is that the meter will measure proper voltage or continuity through an iffy connection (loose or dirty), then when current flows through the circuit the iffy connection gets hot and opens up. Pretty common for starter problems, because they draw a lot of current. In your case, since you have high beams, it might be a bad connection at one of the connectors on the way back to the dimmer switch. It looks like C-2 is on the low beam circuit, it doesn't branch off to the high beam indicator. Red with black stripe by the color diagram. Good luck. It's a tough one. High and low share the same power source so it has to be on the ground circuit if the high beams work.

So you're making progress. Not clear what "proper wires switched on" means. Sorry. Just don't know. Based on the diagram you should be able to take the pug that connects to the combo switch and jump the wires to see if it's the lights or the switch. Be the switch. Make sure you pick the right pins, and use a test light as the jumper if you want to be safe. The test light will stop you from creating a dead short.

Bad gas is hard to diagnose. It just doesn't light up like good gas. You could drain your float bowls and refill them with known fresh gas as a test. Did you check that when you pull the choke knob/lever that it's actually moving at the carburetor? You might be pulling the knob but nothing really happens. I'm just throwing out guesses that I might try if I had the car and the problem.

Pumps are actually getting cheaper. The zcardepot pump picture looks like an Airtex. They used to cost ~$99. You should post the actual links. The pictures aren't worth too much for figuring out value. https://www.rockauto.com/en/catalog/nissan,1977,280z,2.8l+l6,1209248,fuel+&+air,fuel+pump,6256

That's a good clue then. Here's another clarifier - were you driving it when it "stopped working" or do you mean it just wouldn't start one day? Any chance you got some bad gas? Did you follow the proper starting procedure? Maybe your choke cable came disconnected and you've lost choke. Only posting to get some carb time. Don't really know much.

Try starting fluid through the carbs before getting too crazy. Confirm that it is actually a fuel problem. I've had weak spark that wouldn't start on gasoline but would on starting fluid.

It might, but there's not a lot of range there if I remember right. The slot is small. There is also some adjustment possible on the pickup coil, maybe. There is on the two pickup distributors, for phase adjustment between the two. Do you still have the old one? You might examine it and see if it has been adjusted. Might b that the PO was one tooth off and made his own fixes.