Zed Head

Actually, it might be a direct short that only happens every few days. Second-guessing myself... Touch the fuse after driving for a while and see how hot it is. Be careful, it might be really hot. That will be a clue if it's a fuse on the edge of melting that finally does after a few days, or if it's a sudden direct short.

The plastic bulb sockets have been known to get hot and deform allowing the electrodes to move and touch things they shouldn't touch. You might pull all of your bulbs and check the sockets. The fact that the fuse lasts a few days suggests that it's not a direct short. It is a current leak to ground or another circuit that is overheating the fuse. See if any filaments are lit up that should not be or that are dimmer than expected. Might be a clue.

Maybe it's from one of the 4 cylinder NAP? ZAP? ... NAPS-Z twin plug engines. Apparently they were vertical. Did you measure the length? That's another possible difference. Gear ratios might be interesting also. From the cloud. I don't know much, just remember them from the wrecking yard in the small trucks. - https://en.wikipedia.org/wiki/Nissan_NAPS https://en.wikipedia.org/wiki/Nissan_A_engine

carpartsmanual shows that the change is at Jul/Aug 73. So, they might be right. http://www.carpartsmanual.com/datsun/Z-1969-1978/body-260z-280z/2-seater/seat-slide http://www.carpartsmanual.com/datsun/Z-1969-1978/body-240z/seat-slide/type-2-reclining-seat

Found it. @zKars

I forgot who made the universal base plates for the distributors. They're a member. That opens up options. For what it's worth, the brand name "Mallory" doesn't mean much for what you're trying to do. It might have some collection value, if it is an actual Mallory-made product from the past. But really, it's two advance mechanisms and a way to distribute the spark. Many ways to get that done. You might put a set of points back in while you're thinking. Then you can get on with carb tuning. Points work pretty well, they've been around for years.

You can see by their diagram that the module grounds through the distributor body and the mounting screws to get to the engine block and complete the circuit . Might be that by loosening all of the various mounting bolts you lost your ground. Attach a wire directly from the distributor body if you want to be sure the module has a good ground. It's actually the most important one for spark strength.

I found a test method for the module itself on Summit Racing's site. Worth reading... https://static.summitracing.com/global/images/instructions/pnx ignitor i tests.pdf

Bummer. Could be that you just lost a connection somewhere. Get out your meter. Don't overlook grounds. The Ignitor I is susceptible to overheating if the key is left on too long. Hopefully that's not what happened. https://images.carid.com/pertronix/products/pdf/1183-installation-instructions.pdf "2. Leaving the ignition “ON” with the engine “OFF” for an extended period could result in permanent damage to the Ignitor."

Did you try the coil main wire to check for spark? Maybe your ignition system is weak or dying and that's why you 've been having problems. You shouldn't be able to get a full twist on the distributor without one magnet at least passing by the sensor. You should be able to generate a spark. The twist is not meant to line up the rotor, it's meant to move the sensor past a magnet, to generate a spark. Make a spark then see if you can get the rotor pointed at a terminal.

Here's an old thread showing the green tape and the magnets underneath. There are six magnets. Might just help you absorb all that's been written so far. We're still at trying to get spark to happen on the #1 plug wire when #1 piston is at about 10 degrees before TDC on its compression stroke. You've pretty much covered all of the separate issues, just need to to put them together.

You could get everything aligned and set up the coil's center wire close to a ground where you can see the spark. Then turn the key on and twist the distributor until a spark happens. You'll be moving the sensor past a magnet instead of vice versa. Move it around until the spark happens where you like it and put your #1 plug wire at the proper spot on the cap. You should be close then.

You're working on a modified system so knowledge of how the ignition system works would help you a lot. Even if you installed the distributor and oil pump shaft exactly as Nissan instructs, the odd parts in the distributor will probably be off. You have Nissan, Mallory and Pertronix all combined. The Pertronix is a Hall effect sensor so you can use a meter to determine when the magnet passes the sensor. But...more knowledge required. If you remove the rotor and take a picture of the top of the magnet ring the position of the magnet might be apparent. It's important. And, just in case you bumped something, the gap between magnet and sensor needs to be right. It can cause sporadic spark if it's not.

Don't forget that the spark happens when the magnet on the shaft passes by the Pertronix sensor. One more thing to line up. Trigger, rotor, compression stroke on #1, plug wire. The magnets have been known to fall off.

Early low number Series(?)1 survivor(?) automatic 1970. Should be interesting. https://bringatrailer.com/listing/1970-datsun-240z-90/

You could probably pull from the top of the open block with a pump like that.

A big pipe wrench and lots of heat. Put it back on the control arm to get more leverage, use a long 5/8" bolt where the spindle pin would go to make it easy. Don't crush the tube.

From a chemistry perspective you'd want the solution moving in the block to keep fresh chemicals on the surfaces. It might be effective to rig up a hose loop from the thermostat outlet to the pump inlet and spin the pump with a drill or even rig up an electric motor and a belt. That would keep any sediment suspended also as it breaks free. Of course, the head needs to be on and sealed.

Today's auction... https://bringatrailer.com/listing/1973-datsun-240z-198/

Once the wheels lock up there is no "faster". Unless you go with wider tires. Then you might not be able to lock them up without more force. A bigger booster will give more force, it's a multiplier. A bigger MC will create less force it's done for volume, to get rid of the travel in the pedal. I'm just teasing out the details. cgsheen's story is a good one showing both feel and fade as concerns. But also in a competition setting. He chose pad and shoe material to achieve his goals. He also probably adjusts the system to remove all play in the linkage and air in the lines, so pedal feel is high and tight. I'd guess. I just saw a brake question on another forum and the guy was asking opinions about "caliper covers" and slotted drilled rotors. That's a whole different angle, the look.

In principle, it should work. The marks on the pulley are based on which wire is fired when they're passing by the pointer. You could also have just moved the timing light pickup to other plug wires until you found the one that was on target. Should have mentioned that. You can still do that if it makes the wires fit better.

What is the goal? Better pedal feel, less force required, racing performance? Can't say what's better unless you define what you're trying to achieve.

Put the #1 spark plug wire on the terminal that the rotor is closest to when all of your marks are linked up and the distributor is in a place which gives you adjustment range. You might get you timing light marks back then. Then you can set your timing and focus on the carbs.

The site has a For Sale sub-forum. Always good to just put your price out there. The scammers just want to make contact then persuade people. Put it out in public and you'll get a better response. https://www.classiczcars.com/forums/forum/11-for-sale/