240Z, 260Z, 280Z Performance / Technical Discussions related to performance motor enhancements, upgrades.

carb conversion

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Old 10-13-2009, 08:31 AM
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carb conversion

im going to be putting my L28E into a 260 roller. im changing heads and i want to run carbs. whats the best way to go? SU's, webbers or 4 barrel? im just looking for your input thankyou
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Old 10-13-2009, 08:59 AM
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Best? Welp... sounds like there's no $ limit on your project.

Build it like Rebello: http://www.rebelloracing.com/nissan1.htm DIY would cut the cost from $10k to about $6k.





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Old 10-13-2009, 12:56 PM
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Id say find you some Early SUs (70-72 240Z Carbs) And try them out first their a little cheaper and even more so if you find them used but not rebuilt
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Old 10-13-2009, 01:40 PM
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they all function just fine, its everything else that makes the difference.
budget, engine specs, personal preference ect.
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Old 10-14-2009, 07:45 PM
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ive heard the 4 bbl isnt all that nice due to different runner lengths. if the motor is better than stock it can cause rich in the center 2 and lean everywhere else. id go su's if you have them, plus they are cheaper and easier to tune and great for stock. if you have more mechanical abilities and have a set of webers near by, or cheap, id go those if your motor has a cam, high cr. etc.
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Old 10-14-2009, 08:44 PM
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Originally Posted by SHADY280
ive heard the 4 bbl isnt all that nice due to different runner lengths. if the motor is better than stock it can cause rich in the center 2 and lean everywhere else. id go su's if you have them, plus they are cheaper and easier to tune and great for stock. if you have more mechanical abilities and have a set of webers near by, or cheap, id go those if your motor has a cam, high cr. etc.
I want to know what su's you are tuning that are easier to do than a 4 bbl carb!! SU tuning is most definitely not for the unexperienced. Not cheaper either. If you are a diy person.

My car ran great with this Frankenstein setup. 2bbl motorcraft carb with a hand made manifold adapter, ported head, and a cam (forgot the specs). It got great mileage (28mpg on 100% hwy) and it was uber easy to tune/ jet down-up. Reliable. Not the prettiest though lol.
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Then I slapped a set of 240z su's on it. Much prettier lol. I never really got them tuned perfectly. And my mileage went to dookie.
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I miss my s30 now :/

Last edited by Sweets; 10-14-2009 at 08:51 PM.
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Old 10-14-2009, 09:30 PM
  #7  
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I was actually thinking of finding a way to use a chevy TBI unit on my Z for ***** and giggles. Not carbs bout would be kinda neat to see. These engines are so simple you can pretty much make anything you want for them lol
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Old 10-14-2009, 11:28 PM
  #8  
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Originally Posted by BlueKitsune
I was actually thinking of finding a way to use a chevy TBI unit on my Z for ***** and giggles. Not carbs bout would be kinda neat to see. These engines are so simple you can pretty much make anything you want for them lol
wont work unless you have something custom controlling it.
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Old 10-15-2009, 01:18 AM
  #9  
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carbs

well i apprecieate everyones input. im 100% tied up into the military, and in iraq at the moment, so i think im just gana take some advice from eirler and just get ahold of rebello. im makin the money to be able to do it. i just dont have the time to rebuild an engine. when were stateside by the time the weekend comes i just wana drink and re-coop. now the problem im having is finding the right cylinder head for my build. ive heard numerous things about n42 and e88 and have no idea what direction to go. im defineatly building a N/A engine, but i want the most bang for the head goes.
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Old 10-15-2009, 01:59 AM
  #10  
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just give rebello a call, they will give you all the info you will ever need. Stay safe over their.
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Old 10-26-2009, 11:14 PM
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Yes, rebello will give you decent information. But you still have to know what you want: no company can set your goals for you. You seem clear about the N/A option: this is my preference as well. I like it for the sound and the particular kind of throttle response. For a N/A zed engine, I think that the true classic datusn sports car sound and feel is achieved by multiple carbs. Call me old fashioned but I just don't think the L-26/28 breathes well with a single four barrel ('tho it is easier to maintain and tune). This leaves SU's, dellorto's, Zenith Stromberg, Mikuni's or webers. Unless you are into making points for restoration, or just looking for the cheapest multi-carb option, set aside SU's. They are not competitive from a performance perspective.

I love webers, and triple 45 MM weber set ups (with manifold) can be found regularly on flea bay or at various zed fora. 45 MM sidedraft's are the minimum: don't get 40's. But while the initial purchase price can be competitive (used, new they are more than Mkuni's), webers can be expensive to tune, not just for the time, but also the parts. The corresponding advantage is more flexibility, but if the car is just a street car with predictable environmental factors (ie you don't drag it to racetracks across the country) this advantage is not huge. A second, more serious disadvantage to webers is that they have harsher shift from primary to secondary: there tends to be a flat spot before they come on strong (a point I recall well from my first webers on a datus 510). I liked that sudden surge in those days, but it does not lead to a smooth powerband experience. But you gotta love the sound of the webers, and they are in the end a fun carb, with good backup in parts and technical knowledge.

The Mikuni's by contrast have a better accelerator pump design, allowing a smoother throttle response. I have been told they sound as good as webers, but I have never run mikuni's so can't confirm. I can confirm mikuni's are cheaper to buy and tune, though, and it is reported that they get better mileage than the weber. But Mikuni parts are harder to find.

I have heard good reports from at least 2 zed owners about dellorto's but I can't confirm one way or the other.

Good luck with your search.
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