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EFI to Carb


Chewievette

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I'm going to be building a street rod in the near future and since I have a 280zx engine available to me I'm going to use it. I'd like to convert it to a triple carb setup but I need to know how. The intake and the carbs are easy, I need to know how to convert the fuel system. Can I use the EFI fuel pump and regulate it down to the needed pressure? What pressure should I be aiming for? Or would it be better to use a carb fuel pump? I read that there are two pumps on the early cars, is that true? Would I need both? I have a couple more questions but I need to get going so I'll be back later. Thanks.

 

btw, I did do a search for this info but it consisted of everyone telling the inquirer to Not do it.

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Guest bastaad525

nope... unless there's some really creative way that no one has done yet, you can't use the EFI pump on carbs.

 

EFI likes ~30-40psi

 

Carbs like 3-5psi

 

Sure you COULD probably find some creative way of getting the pressure down but it'd be much cheaper and easier to just buy a low pressure pump. You could probably get away with just running the stock 240z mechanical pump if you have the opening on the side of the head. I ran the stock pump on my 2.9L motor, made 170whp and plenty rich on stock SU's.

 

low pressure pumps aren't even that expensive.

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I'm going to be building a street rod in the near futureQUOTE]

 

If your aim is to build a street rod then why not invest that 1800 plus that youd spend on a triple carb and intake set up on a chevy v8 engine and transmission, if you look around youll be able to pick up an engine transmission combo for about 500 in good working order and youd already have more power than you could make with a triple carb setup on an l28, unless you had a few grand into the engine after the big chunk for the carbs. If you are dead set on going with carbs on the l-28 check out some of the threads on the 4 barrel conversion from arizonazcar.com. Its a one carb set up for less than half the price of a 6 pack. That is the set up that i am ordering today to run in my 78 until i can build up my 350 v-8, so I can build it and beat it at the same time!

 

 

and fyi hotrod=v-8 :-)

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http://www.arizonazcar.com/manifold.html

 

and go onto jegs to get the carb, a holley 390, model 4160 i think, and get the accessory kit for it, it comes with diaphraghm springs and an inline fuel pump. for the holley with the kit and free 1-2 day shipping i paid 324.96. From what i understand the carb works great right out of the box, and they reccomen a 5-7.5 psi pump, you can get an inline rated for that at napa for like 40 bucks

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Guest tony78_280z
http://www.arizonazcar.com/manifold.html

 

and go onto jegs to get the carb' date=' a holley 390, model 4160 i think, and get the accessory kit for it, it comes with diaphraghm springs and an inline fuel pump. for the holley with the kit and free 1-2 day shipping i paid 324.96. From what i understand the carb works great right out of the box, and they reccomen a 5-7.5 psi pump, you can get an inline rated for that at napa for like 40 bucks[/quote']

 

DO IT!! This is something I wanted to do. When I choose to go with a carb I had to make the choice of keeping the L6, or go v8. I choose to go v8, and where I don't regret it (I think I bit off more than I could safely chew at the time), I still wonder "what if" I would have kept the L6 and put on a carb, cam and headers. I would encourage you to go with the holley 390 and ArizonaZs intake. Tune the carb acuratly and then give me (us) some good stats on performance.

 

From what I hear, you can get a pressure regulator that has a return line and regulate the efi pump down to the carb requirements. Don't do it without doing further research as I am not positive.

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I've got a triple weber setup lined up to purchase in the next week or two. I've decided to buy an electric pump for carb'ed engines so I dont have to install extra fuel lines. I might also be getting a new head in the same deal as the triple setup, but I'm not sure yet. I've been planning on a new cam and headers from the start so when I get it on a dyno I'll let you know how it does. Its not an out of the ordinary setup by any means but it'll be good to get something on the dyno again and I'm sure you guys wouldn't mind hearing the results.

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i know if i switch to a 280z round top carb, with all that emissions crap, i could pass visual.

EFI to carb is not CARB legal. ANY smog tech will fail you as soon as they open the hood. Smog isn't what it used to be. The penalties for passing cars that aren't legal are getting a lot stiffer, and the techs are A LOT more knowledgeable.

Nothing like going back 20+ years in technology.

20+ years huh? How old is the crappy FI on a 75 280Z? My math says 31 years. And the FI sucks, and it would be EASY to make more power with carbs. You may say more sensors and electronics are better, but I'll take the hp anyday.

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If you want to know why I'm switching to carbs its because I have a business where all I deal with all day are efi cars with computers that are always a pain in the behind and my daily driver has the most idiotic computer system that you or I can imagine so I just dont want to deal with that right now. I have used carb systems before and they are very very Simple and that's what I'm going for! I dont really care if I have to constantly adjust the carbs, that's half the fun! If your not tinkering with your car then its just sitting there, I'd rather be working on it.

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