I need help changing to a Carburetor - 78 280z

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01-01-2004 | 08:10 PM

Zach280z78

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I need help changing to a Carburetor - 78 280z

I have a 1978 280z coupe non-California model. I just got it repainted 2003 Viper Red 1 Stage Coat. My fuel injectors have gone to **** and I really don't like regulators. I guess it is just the rebel in me. So I went out and got the 4-barrel Intake Manifold from CarTech, but I'm not 100% positive about the other parts I need to modify to go along with the Fuel-Injection to Carburetor Conversion. Do I need to change the Fuel Pressure Regulator, Fuel Damper, Fuel Pump, etc? Do I just rip out the whole ECU system and all the Fuel-Injection Intake? What sensors do I leave alone? I'd like to think I know what I'm doing out there, but I would rather not take the chance of doing anything wrong.

So PLZ if anyone has done this before or knows what I should do PLZ give me as much information as possible and in detail and if there are any websites you could give me it would be very appreciated THANKS.

01-02-2004 | 01:48 PM

auxilary

the Dude

Joined: Mar 2002

Posts: 381

From: Bay Area, California

if you're swapping to carb, easiest thing to do is get a stock set of SU round top carbs with stock intake manifold. you will need to procure a set of choke cables, yank out your ecu, and probably not use half of your wiring harness. everything forward from the intake ports can go in this case.

01-02-2004 | 02:26 PM

Zach280z78

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I want a carburetor with secondary's. I like the feel of the kick. So the SU's isn't really what i was thinking

01-02-2004 | 03:37 PM

auxilary

the Dude

Joined: Mar 2002

Posts: 381

From: Bay Area, California

weber dvg/a 32/36 carbs

01-02-2004 | 03:45 PM

Zach280z78

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I know what's out there and my options. I already decided on a 4 - barrel. I know what 4 - barrel im going to use. I just need to know what stays, what gets modified, and what gets junked as far as the fuel system goes. If anybody has done this modification going from fuel injection to carburetor plz explain to me what you did. Any input would be appreciated.Thanks

01-05-2004 | 02:40 PM

Bleach

The Evil Twin

Joined: Mar 2001

Posts: 9,296

From: Seattle, WA

You will need to change your fuel pump and not use a pressure regulator. For the 4-barrel, you'll probably utilize the return fuel line. A carb fuel system runs about 3-4 psi where the FI runs about 40psi. Use a fuel filter for carbs.

01-05-2004 | 06:01 PM

Zach280z78

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why cant i use the fuel pump i already have since it is electric the new 1 i get will just be electric 2. why not just stick with the pump i got now and get the new regulator?

01-06-2004 | 11:39 AM

Bleach

The Evil Twin

Joined: Mar 2001

Posts: 9,296

From: Seattle, WA

Carbs dont' use a regulator! That fuel injected pump will be pushing way too much pressure I believe. A fuel pump meant for carbs pushes through the same size tube, but at a much lower pressure and they use a simple valve and floats in the carb to "regulate" the fuel level in the bowl. The rest just goes through the return line. You may be able to use your current fuel pump but its probably not a good idea. You may end up flooding out. ummm... do some research into how carbs work. You'll understand.

Its easy too. Just get the electric fuel pump from a late 240Z or 260Z.

01-07-2004 | 11:00 PM

stev240z

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Ive tried using the stock pump and regulating it down it doesnt work.... I got it to regulate correctly but the pump failed quickly

i spent more $$$ on the holley regulators (2 cuz i ran SUs) than I did on an aftermarket fuel pump

FYI

The FI wiring harnesses are all stand alone from the rest of the system. You can take it out. It goes onto the intake manifold, across to the battery, and under the dash. There are abut 4 wires under the dash (one goes to the same wire for your tach) and the main harness for the ECU.

You can take all that out. Thats it. The rest of the sensors and stuff on the engine can be left alone.

Good luck!

11-23-2014 | 07:06 PM

#10

Doug Horvath

Registered User

Joined: Oct 2014

Posts: 17

4 Barrel 280z

I've done it and it's easy... I even used the original plenum, just cut a hole in the top and built my own adapter. The fuel pump can be used, just use the return line to take the pressure off. Put a crimp in the return line if you need more pressure, no problem. The whole of the FI elec wiring can be trashed w/o issue. I agree w/ the thought of the "kick" from the secondary cause it is very cool and your z will take off. Here is a pic of the install. cool... ckya dj