280z EFi to Triple Webers

[Classic Z]

Hi

I have just ordered a set of triple 45 webers with mangoletsi intake manifold for my 1977 datsun 280z. Just removed all EFi (harness, ECU), inlet manifold and exhaust manifold. Also removed charcoal canister and what I beleive is the AC vacuum chamber/canister.

I have been looking on the internet, including YouTube and can't seem to find a detailed list or video of what do do with the following bits. If there is a good thread or link please let me know or if someone has done this already and willing to help that would be great.

Following queries:
1. There is a vacuum line from the top of the rocker cover to the old intake manifold. Do I just plug that with a sort of air filter as I have seen in various pictures? If so where can you buy one from?

2. There is a pipe coming out of the block. I beleive it is a crankcase ventilation pipe. There was a pipe from this going to the old intake manifold. Again, do I just plug with an air filter or run a pipe somewhere?

3. There seem to be 4 steel fuel lines running from the back into the engine bay. One is the main line, one is a return line and one seems to be for the charcoal canister which I have removed. The 4th I am not sure yet. Do I only need the main line now that I have removed the other bits? Do I just plug the rest or is it possible to remove them and just run 1 line from the tank?

4. Now that I have removed the Efi harness; if I wire up my low pressure pump in the back of the car will the car start or do I need to rewire it somehow? I am just installing a low pressure pump without a fuel pressure regulator. The car has had a distributor from a 280zx installed before I bought it.

5. Lastly, does anyone know if I can simply remove the fuel vapor/fuel vent tank in the quarter panel. It seems like a very complex system. I cant see why its all needed. I wonder if its of value or just for the emissions reasons. Was thinking of just removing it and all the hoses and just running one hose to the fuel filler neck for breathing purposes.

 

[jonbills]

1 & 2, yes, thats right. you can get all sorts and sizes on ebay.

I'd keep the return line, but do what you have to to keep the pressure at 2-3 psi.

 

[moggy240]

When I fitted my Mangoletsi manifold the mounting studs for the carbs were imperial and not metric which surprised me, but it should come with the mounting nuts.
I had to change mine for mounting jenvey's that's how I found out.

 

[Classic Z]

1 & 2, yes, thats right. you can get all sorts and sizes on ebay.

I'd keep the return line, but do what you have to to keep the pressure at 2-3 psi.

Great. Thanks.
With regards to the brake servo vacuum line that use to go into the old intake Manifold. Does that just plug into the new intake Manifold?

 

[moggy240]

Great. Thanks.
With regards to the brake servo vacuum line that use to go into the old intake Manifold. Does that just plug into the new intake Manifold?

Yes

 

[Toe-B]

Has anyone figured out what to do with the fuel pump after the efi harness is removed? I'm doing the same conversion and am a little stuck.

 

[Classic Z]

Hi

You need to fit your low pressure fuel pump in place of the high pressure fuel pump on the car for the EFI system.

You then need an electrician to check the wiring as when you remove the EFI system and ECU your car may not start.

I had to have some wiring work done on mine. Once that all done and all is installed take it to a rolling road specialist so they can set it up properly. This makes a huge difference and will drive really well after.

If you need any more help let me know as I have been through all of this recently.

 

[Toe-B]

Hi

You need to fit your low pressure fuel pump in place of the high pressure fuel pump on the car for the EFI system.

You then need an electrician to check the wiring as when you remove the EFI system and ECU your car may not start.

I had to have some wiring work done on mine. Once that all done and all is installed take it to a rolling road specialist so they can set it up properly. This makes a huge difference and will drive really well after.

If you need any more help let me know as I have been through all of this recently.

What exactly did the electrician need to do to get the fuel pump and other computer controlled components to work? This is the home stretch of my conversion and I'm getting a little confused.

 

[Classic Z]

Sorry. Can't help with that bit. That's why I sent it to him. I tried for a while to figure it out but had enough.

 

[richiep]

Hi

I have just ordered a set of triple 45 webers with mangoletsi intake manifold for my 1977 datsun 280z. Just removed all EFi (harness, ECU), inlet manifold and exhaust manifold. Also removed charcoal canister and what I beleive is the AC vacuum chamber/canister.

I have been looking on the internet, including YouTube and can't seem to find a detailed list or video of what do do with the following bits. If there is a good thread or link please let me know or if someone has done this already and willing to help that would be great.

Following queries:
1. There is a vacuum line from the top of the rocker cover to the old intake manifold. Do I just plug that with a sort of air filter as I have seen in various pictures? If so where can you buy one from?

2. There is a pipe coming out of the block. I beleive it is a crankcase ventilation pipe. There was a pipe from this going to the old intake manifold. Again, do I just plug with an air filter or run a pipe somewhere?

3. There seem to be 4 steel fuel lines running from the back into the engine bay. One is the main line, one is a return line and one seems to be for the charcoal canister which I have removed. The 4th I am not sure yet. Do I only need the main line now that I have removed the other bits? Do I just plug the rest or is it possible to remove them and just run 1 line from the tank?

4. Now that I have removed the Efi harness; if I wire up my low pressure pump in the back of the car will the car start or do I need to rewire it somehow? I am just installing a low pressure pump without a fuel pressure regulator. The car has had a distributor from a 280zx installed before I bought it.

5. Lastly, does anyone know if I can simply remove the fuel vapor/fuel vent tank in the quarter panel. It seems like a very complex system. I cant see why its all needed. I wonder if its of value or just for the emissions reasons. Was thinking of just removing it and all the hoses and just running one hose to the fuel filler neck for breathing purposes.

1: you need K&N breather filter #62-1340. E.g.
https://www.ebay.co.uk/itm/274557300514

2: K&N filter #62-1420.

1,2: alternative is to route one or both to an oil catch can of some kind mounted in your location of choice in the engine bay. Doesn’t really have an advantage on a road car that isn’t used very often and isn’t chucking lots of blow-by muck out!

3: you just need one send and one return line, with a low pressure regulator somewhere in the system to bring down to 3-4psi. Note: for triple setups you can run without a return line. My 71 Fairlady Z with triple Dellortos has run that way for 13 years without an issue. I use a Sytec regulator for carbs mounted just before the carbs (it’s actually mounted to the rear-most carb).

4. the typical fuel pump/regulator setup with triples is a Facet Red Top pump with some sort of inline fuel filter and regulator. If running like mentioned above, regulate in front of carbs; if using a return line, put the regulator after the carbs. Pressure 3-4psi, depending on how it feels (I run my 40s on 3.5psi).

5: ditch the expansion tank and simplify/plug extraneous hose outlets at the tank. Non-US cars didn’t have all that junk from factory, so go ahead and delete.

On the subsequent post about computer controlled components - there shouldn’t be any after the FI is removed for a carb conversion. The low pressure fuel pump can (should? IMO) be added with its own new wiring, and something like an oil pressure cutoff safety switch at the oil pressure sender. It’s dead simple to wire up and can be connected via a relay to the battery positive for constant 12v with a switchable source, e.g. at the starter solenoid or similar. Ignition - use 280zx dizzy or something like a 123ignition, as has been documented on the forum. Everything else that may have been connected to the ECU is unnecessary, e.g various sensors.