Zed Head

I was thinking of the wrong thing when I mentioned the PCV system. That is the flame arrester. You might be on to something with the anti-backfire valve. I don't know how to check it, but it appears to open the large passage when vacuum is applied to the small tube. You might check the hoses and see if the valve opens correctly.

Leaning out might be be going the wrong way. The anti-backfire screen in the PCV hose isn't for exhaust backfires. When you say "backfire" do you mean one big pop or a string of small pops? Seems like you're also suggesting that there were no backfires before installing the MSA exhaust system.

You can count revolutions in 5th gear. .745 is less than 3/4, .773 is more. 3/4 is fairly easy to lock in on. I had a .773 and that worked for me. Also had a .745.

There were two variations of the ZX 5 speeds, according to the FMS's. Only the 5th/overdrive ratio changed.

Could be that they changed over the years. "New OEM genuine Nissan exhaust manifold to exhaust pipe stud. Will fit Datsun 240Z, 1970-73. These are 8mm studs, 38mm overall length. *Starting around 1974-75 these studs changed to 10mm. See PT# 800-257." Z Car Depot IncExhaust Manifold Flange to Pipe Stud OEM 240ZExhaust Manifold to Pipe Stud Set OEM 240Z - 200-517 (). New OEM exhaust manifold to exhaust pipe studs with stainless steel serrated locking nuts.

No offense intended, I had OEM in mind after I made my own post. I was actually going to suggest calling your local Porsche dealer and getting "factory" boots. Knockoffs and counterfeits are a big problem these days. The injectors get pretty hot. I made the mistake of using shrink tubing with adhesive when I replaced my crunchy old connectors with Volvo connectors. I just spliced in the wires though, no depinning. After the first drive I had puddles of glue on the heat shield below them.

Are you sure that they are real OEM? The description implies knockoff. Here's a comment from the seller's reviews. Translated using Google. cgsheen1 pointed out the need for high quality. "I purchased this item in Austria to test its compatibility with my car (I would later purchase other items). They sent me a package from Thailand. In addition to the delivery time, I also had to pay a customs fee equal to the amount already paid. If I had known, I would not have bought anything. The seller is not recommended and uncommunicative, terrible."

This is typical AI slop. "L-Series to KA/SR Swap" doesn't actually mean anything. Replacing a bearing is not machining. It's not a "counter bearing". Just pointing it out. The garbage is collected with the good stuff then blended together, creating more garbage. The work required is actually pretty simple for a machinist. You could take the ZHome instructions to probably any machine shop that does automotive work and they'd get it. It's not really speed-shop level. Enlarging a hole, abrading away a relatively small amount of material inside the case, and maybe enlarging the countershaft beaing hole. You can swap the bearing instead. The bearing work requires the most precision Godzilla's deal might be a good one if it's real, considering machine shop rates. You'll save some money if you swap the countershaft bearing to the smaller one. The reverse switch work will cost you also, if you choose to have it done. You could mount a switch on the gear shift lever, otherwise. I've only done one, sounds like @EuroDat has done many. He might have other opinions/advice.

Like eBay Dubai or some other Dubai-based company? Just wondering why somebody in Dubai would have NOS Nissan parts.

Porsche dealership? https://www.autohausaz.com/pn/15238836-1287013003

What the heck is that? How does it spin? You can move the coupling sleeve by hand and try all of the gears. Looks like a great deal.

Re question #1 - there should be a thing with two mounting holes, apparently rectangular in shape. According to the Body Electrical chapter. Intermittent wiper speed control. You have a 1976 right?

Stretttccchhhh - the indicator bulb in the tachometer. Can't find it in the wiring diagrams but I know it's connected somehow. Found it. It's a branch off the main light circuit from the combo switch. Would still be the plain old filament bulb unless you changed those also. You're posting but I'm saving anyway...

What's going on with the front signal bulb and socket? It's part of the full turn signal circuit. I browsed back but don't see it mentioned. Might have missed it. Swap the bulbs or LEDs or whatever you have up there and see if it follows.

It's cramped but I think that you can use vision and feel to determine if they are working correctly. You'll probably see old crusty hose and signs of leakage and end up on a difficult weeks or months long repair project. Beware and good luck.

I meant electrical noise. For anyone browsing the threads - https://en.wikipedia.org/wiki/Noise_(electronics)

Other "things that run when the engine is running" - the fuel pump? Maybe it's noisy. It's in the vicinity. You can run the fuel pump without the engine running by propping open the AFM vane with the key on or by removing the small wire to the starter solenoid and turning the key to Start. If you have AC and have it turned on that's another possibility. p.s. I almost wrote this earlier but it seemed like might be a distraction - if it is electrical noise a condenser/capacitor on the power or ground lines might clean it up. I had a weird situation with a tachometer on my 76 that would only work if there was a condenser (like those on the alternator) on the coil negative circuit. Non-classical usage and not something that I can explain. But it was a real thing.

The difference between running (alternator power) and not running seems like it should mean something. Something odd like ground loop currents. I assume that the boards have small microprocessors. Maybe they're sensitive. Instead of trying to find a bad ground you might try adding new grounds. See what happens.

How do you know?

This seems like a voltage problem, since voltage would be higher with the engine running. Or possibly a voltage quality problem from the alternator. Ripples or spikes or noise or similar. If it was mine I think that I'd pull the boards and switch them for a test. If the problem stays on the driver side it's the harness, if it switches it's the board. Or if there's enough play in the harness switch the wiring. You might have a board that's sensitive to the higher voltage or the quality of it. Basically - collect more clues. Determine if it's the board or the harness. There are many components on the board, any one of which might cause a problem.

I had a similar thought about checking hose temperatures but realized that if the valves are closed flow will be stopped. No way to tell if it's valves or a core blockage just by hose temperature.

When I rebuilt my rear brakes I found that the shoes that I had bought didn't fit the drums well. Their curvature was a fit for a larger drum. They only contacted the drum at the ends. If your guy thinks the drums are too worn he'd only see contact in the middle or edges. Beside that, doesn't he have drum-turning equipment? But, as CO suggests, it's best to get the hydraulics working correctly before worrying about the hardware.

I'd buy a couple of 11 oz mugs if they were at $10 each. No offense intended, just my reality.

There are two water control valves for AC cars. One simple thing that you can do is to just stick your head under the dash and watch what happens. Not uncommon for the water **** cable to get bent and stop moving the ****. And the vacuum **** works on vacuum of course, which comes from the vacuum tank. I had a hard time keeping the supply line to my tank from splitting. No vacuum, no heat. That was my clue. You have to check all of those things.