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280zx- converting to carbs


Guest dawg95_2000

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Guest dawg95_2000

What is necessary to convert a fi zx to SU carbs? Carbs, manifold, proper fuel pump, and regulator and what do you do as far as ignition? Do you replace the distributor with one from a 240 or 260?

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Guest bastaad525

You live in a state where smog wont be a problem? If not converting to carbs is a big no-no. otherwise it's a basic swap. All you'd need (assuming you're going with SU's?) the carbs, manifolds, balance tuble, throttle linkage, mechanical fuel pump... and that's it. I dont think there's a pressure regulator... Ignition can be left alone.

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  • 1 year later...
Guest DoTheDrew888

Sorry to bring up an old thread but I couldn't find the info anywhere else.

 

Ok I am going to covert my 280ZX to SUs also. I know I need the above mention parts but I have a few questions. First, will the mechanical fuel pump work with an N47 head? What do I do about the electric fuel pump? Are there any unexpected problems I might run into when I do this conversion?

 

If there is some one here who has converted a 280Z or ZX to carbs and is willing to help I would love it if you posted a "How To" kind of thing.

 

Thanks a lot,

 

-Andrew

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Yes, i agree with ed. The problem with most 914 owners is that when they get fed up with the fuel injection, instead of fixing the problem, they swap over to carbs. Fuel injection is far superior to carbs! I have noticed this happen to a few 280z's over the years, and in the long run, maintenance becomes more of an issue. Tuning on a carb car can be tedious if you don't know what you are doing, and FI is foolproof, for the most part. Make sure you know what you are getting into.

 

N47 had no fuel pump hole, P79 did not either, but the N42 and the P90 still had the holes.

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I'll speak up in favor of the SU carbs. My 75 280z had a 'gone for a CRAP' FI system on it, and I could have easily spent thousands of dollars and countless hours trying to fix it. Instead, I bought some SU's w/ manifold and a 280zx distrubutor fairly cheep, and basicaly 'slapped' them on. (spent a few hours disasembling and cleaning them up, a few gaskets and they're ready to go!) I love the SU's in part because they are so easy to set up and tune.. they are much simpler than the arcaic mid 70's FI system. I'm not running a meckanical pump though; I just got an aftermarket fuel pump intended for 1980's chev P/U trucks w/carb motors. It pushes 4 - 5 psi and I havn't had a problem yet (going on 2 years like this now) mind you it cost me $60 for the pump.. :icon8:

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I wouldn't refer to EFI as "arcaic" when your using carbs that are older than EFI... If you like mpg and you don't like messing with your car alot I would stay EFI and just fix the problem those systems are not that complicated at all. Easy to tweak also.

 

If you want to have something to play with and don't mind the low mpg.. then go ahead and swap to carbs. I have triple webers and I work on them routinely... if your going webers... you can't use your current dizzy very well. I believe the SU's will work fine with vacummn advance dizzy.

-Ed

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Heh.. we gota stop meeting like this Nismo.. :) Well, I'm gona keep refering to it as arcaic.. Sure I'm using carbs 4 years older than the STOCK 75 FI system, BUT I cleaned them up and made them work almost as good as new for a very little amount of money and time. (price out all the required sensors and what not required to make the FI like new.. :shock: ) Besides.. these carbs were 'tried and tested' by the early 70's, while the nissan FI was still in it's infancy so to speak.. oh and I set my carbs ONCE, and drive all summer with NO messing around with them every few days/weeks. As for MPG, if thats a big deal for you, I'd say buy a honda civic or something.. :lol:

 

Have you done a lot of tuning on the old FI system? From all I've learned it's a little hard to work with, and doesn't respond that well to engine modifications... Hell, even trouble shooting is a PITA. Lets see here.. AFM with flaping obstrucion, a throttle valve switch; two positon.. not really too acurate... (although, the zx went to a position sensor, better.) No O2 sensor, a thermotime switch that tells the ecu how hot the engine is, and then decides what to do with igniton and fuel.. AND.. it's all 30+ years old and getting worn out.. YECH!!!! Sorry, I'm not into playing with that crap.

 

Simple answer to the question asked; Pick up SU's w/manifold, keep zx dizzy, get a low presure fuel pump. Good to go.

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Guest DoTheDrew888

Nismo, one thing I am not too worried about is mpg haha. I knew my car was going to be a gas gozzler when I decided to go crazy on the engine. Also, I am constantly playing with my car and fixing/tuning something so one more thing to mess with is a good thing haha. I am really not a big fan of FI, especially my stock 280ZX FI. The system just cannot handle the cam that I put in. I know carbs might be a hassle to begin with but in the long run I think I will be happy with them.

 

Datsunlover, after a little research and talking to a few people I have a pretty good idea on what needs to be done. Still, any input would be apprieciated.

 

Thanks guys,

 

-Andrew

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