Zed Head

Are you losing spark or injection? The resistor is part of the 280Z tachometer circuit. Here are the instructions for the Crane modules. People often have problems when they use aftermarket ignition on the 280Z EFI systems. Not sure why. I have had odd problems with loss of injection if the ECU doesn't like the tach connection. https://static.summitracing.com/global/images/instructions/xr700 instructions.pdf

Edit - It might be just a partial conversion. Just realized that you did not read the CL ad. If you read it you'll find - "Nice V8 scarab conversion with engine still intact." https://datsunforum.com/the-scarab-legend-the-original-hybrid-datsun-z/ "As time has passed, the number of legitimate Scarab conversions have become cloudy – Some claim less than 200 “factory” Scarabs were ever produced, while others put that number upwards of 270. Adding to the confusion, many “customer cars” were converted by Scarab – and even more were converted on a DIY basis by owners in other states, as over a thousand conversion kits were sold during the life of the company with an approximate price tag of $1200. Some customers opted for all of the upgrades, some just wanted the V8 swap..."

The engine seems to be in the Scarab position. Jammed against the firewall.

Some sources call it the Auxiliary Air Regulator. AAR. If you look closely at where it attaches you should see a plate underneath it with heating cooling lines attached.

That would be because the coolant plate underneath the AAR has heated up. That means that the valve is not binding. All signs point to no electrical power through the AAR heating coil. Unlikely that a vacuum leak would disappear when the engine warms up. Just trying to be helpful.

This video just popped up. Interesting results.

The math is correct. That's about all that can be gleaned from your post. You'll want to match the pistons to the heads, not the block, to get the desired CR. The L28 was used for small and large combustion chamber heads, the pistons were changed to achieve the desired CR.

His problem is with the AAR, not the thermotime switch. The AAR has power as long as the fuel pump has power.

You can also stick a Noid light in the connector and start the engine. The light should stay on when the engine is running.

It's on the same circuit as the fuel pump. Looks like it grounds through pin 34. You can test the whole circuit at the ECU connector. The FSM instructions describe how to use the Start circuit to actuate the fuel pump relay to provide voltage. But you could also just disconnect the AAR and test for voltage at the AAR connector with the engine running. The AAR should get power when the fuel pump does and the fuel pump only gets power when the engine is running.

This is a sign that there is no electrical power at (edit - actually should say "passing through". The ground side must be there also to complete the circuit) the AAR plug.

There should be no skipping or jumping ever. You broke something. Probably not worth fixing, even if it's possible. Find a new diff. Consider an R200 conversion, Nissan started using them to take the torque of the L28 engines. p.s. please post pictures of the destroyed gears or shafts after you open it up.

Pretty easy to siphon from the Z cars. On your 75 you can see right down in to the tank through the filler neck. Use an Oklahoma credit card. Should easily get the level down to where you can at least try to replace the sender without dropping the tank. Looks cramped under there though. Good luck.

Unbolting the fuel rail would remove the heat path that Jeff G described. Insulation won't help that. Conduction, convection, radiation.

Did you do these three things at the same time? Maybe there's a problem with the transmission, not the rims or tires. Or maybe something got bent when the car was lifted to put the wheels on. If you used the rebuilt transmission with the old wheels and didn't have the problem then you can narrow it down to what happened when the wheels were put on. Since it worked well before it is most likely a problem that was created when the recent work was done. Don't get distracted by other things. Look at the work that was just done.

So, considering your last post about deadheading the metal rail, it seems that the big difference might be the rubber hose versus metal lines. Maybe the key is fuel temperature before it gets to the bowls. The cooler the better. We've talked about fuel differences in the various EFI heat soak threads. Fuel quality varies across the country. Might explain the AL versus MI difference. Could be a winter blend thing also. Jeff G were you running aviation or race fuel, or pump fuel?

That is pretty severe "vapor lock" if it happens just sitting at idle. Is this on a car without a fan shroud? Sitting out in the hot sun with the hood closed? The carbs need air flowing past them to cool, the coolant flow is for the engine. A quick test might be an electric fan under the hood pointing at the carbs. See what happens. Jeff G, is your deadhead mod using the mechanical pump or an electric pump? Your solution creates more pressure in the supply lines. I wonder if VaCat33 has the proper orifice in his return line. Or if a smaller one would help. A quick test might be to clamp the return line to create a deadhead system. If it helps then your solution should do the same. Things to "try" that might shed some "light".

Yes, they're both up under the dash behind the glove box. Easy to see. The vacuum cark has a vacuum hose connected to it. If I remember right if you lose vacuum to the vacuum tank it stops working, no heat. So your problem might be under the hood. I had a problem with the hose splitting, and got used to fixing it when I suddenly didn't have heat.

Could be the vacuum cokc. It controls coolant flow through the core.

Was the disc installed backward? It looks all beat up at the hub nose piece there.

A picture would be neat. You're saying that Mcleod's products are of low quality. Which do you have, it looks like there are two types of disc. https://www.mcleodracing.com/sport-compact/c28 Any aftermarket disc should work. Pick your favorite brand. https://www.rockauto.com/en/catalog/nissan,1976,280z,2.8l+l6,1209226,transmission-manual,clutch+friction+disc,10605

The play looks okay, but does it work? Don't forget to put the return spring back on. Also, with the rubber boot off it's more apparent that you probably have a short throwout sleeve/collar. The fork should start a little ahead of the middle of the hole. Yours is pretty far back. Probably close to hitting the back of the hole at full stroke. It will probably work. Earlier I think I said that problems might happen as the disc wears. But actually things should get better since the fingers get closer to the TOB as the disc wears.

The leak in the MC would be internal. Unable to build pressure at a certain point in its travel, then lets the fluid back in to the chamber as the piston retracts. The slave cylinder can contain a lot of fluid inside the dust boot without leaking. You need to get proper travel from the hydraulics. It's critical.

I had a weird situation where the slave cylinder was leaking and I only got 1/2 of the expected travel from the cylinder. It moved when I watched it but it wasn't moving far enough. Could also be a leaky spot in your MC. I would measure the travel distance to be sure that you don't have a hydraulic problem. I think that EuroDat has published the distance that the slave piston should travel. I haven't figured out if Nissan meant that available/possible travel was 1.38" or if the piston was supposed to travel 1.38" when the pedal was pushed. Not clear.. I think that they must mean that it should be 1.38" when you press the pedal, since the end of the bore is open, and full stroke would be essentially unmeasurable. Either way, it would be good for you to know the number. And, if you do take it apart consider getting a later clutch fork and use a self-adjusting slave cylinder. It's an improvement.