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88 VG30i Carburetor swap


Cory74700
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I am looking to swap out my TBI for a Carburetor, anyone have any advice as to which 2bbl carb from Redline Weber would work, but especially I need info on intake manifold modifications, wiring, rerouting lines/ hoses etc... Any help is much appreciated and thanked for in advance.

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Years ago Jim Connor Racing sold a kit to swap the TB over to a carb but they were using a Holley carb, 500CFM, the kit included the intake manifold, air cleaner, linkage, etc, they were claiming a 45% increase over stock when used with their headers and cams. Unfortunetly JCR is no longer in business.

 

Can't recommend anything as far as a Weber, you may want to send them or one of their distributors an e-mail to inquire if they sell a kit for the Nissan V6 engine.

 

Original JCR catalog page shown below:

 

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Ok thank you both for such a quick response, ill get right on with emailing them and furthering my research, my whole intent for this is that I only see two forms of an intake, efi or a carb, tbi is just an effed up carb. efi guarantees no power increase but a carb is proven to even if it lowers my current 30mpg+ by 5-7mpg that's no big deal, I have an outstanding ability to be able to tune engines for better than optimal mpg.

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I would like to know how you manage to accomplish 'optimal' fuel mileage, especially since you claim 30 MPG with a TBI equipped motor?

 

You insight would be greatly appreciated by those in this community.

 

Thanks, and Merry Christmas.

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To start off I did some more calculating and I actually get right now 38mpg, but don't know if your familiar with California or not, but I live 50 miles north from Sacramento, and to Petaluma down along the coast is an additional 83 miles, and I can go from my house to Petaluma and back on 1/4 tank of fuel thats roughly 133 miles each way so 266 round trip, my fuel tank is 20 us gal. The first quarter is 7 us gal. the remaining is 3.25 us gal, don't ask how that works thats just what the capacity test showed, but I started off when I first got the Pathfinder by replacing all the spark plugs except the furthest back on the driver side, (if you've tried to replace the plugs on a vg30i you'll know why I didn't replace that one), then I got a K&N free flowing air filter, then replaced the fuel filter with two filters piggybacked to ensure my 108 octane mixed with ether was as pure as possible, replaced the injectors with Bosch low flow injectors, (which was a bad idea since 108 mixed with ether is on the thicker side requiring me to clean them thoroughly) but the mixture I run burns hotter and slower meaning I don't require as much fuel in the chambers to ignite and send the piston the opposite direction. Because of that I then had to modify the ECU to tell the fuel pump not to flow so much through the lines. Also to accommodate for the hotter slower burn, which makes a better explosion, (I'm at 2,700ft elevation) I use 25W-50 Royal Purple Synthetic Motor oil. Also I'm not sure if it made a difference to fuel economy, it sure as hell made a power difference, but I ran almost all my ground wires to my engine block.

 

That pretty much sums up my fuel efficiency tactics. If you don't want to believe that any of its true, then don't, but when you top 470,000+ original build miles and want more fuel efficiency you'll start to tinker too, I come from a family of mechanics that go all the way back to working on the 1908 Ford model T and model S cars through to this day.

 

 

Merry Christmas to you as well.

Edited by Cory74700
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:wackinit:

 

You'd need a Saudi vacuum advance distributor (good luck), or make your own. There's nothing wrong with the TBI per say and it works pretty well when it works right. MPFI from TBI is about a 15HP increase in power (I've done it). What did you do with the ECU? Rommulator and a Prius tune? Remove the full B+ relay so the ECU only sends the pump 9V? Stock FPR? What is your timing set at? Why do you have sludge for oil in a tight tolerance engine?

 

Back plug is easy to get to, give it a good ol' reach around.

 

Your tank is 21 7/8 gallon so basically 22 gallons. Is your odometer 100% accurate?

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I never said money for fuel was an issue, I want a clean burning motor that stays clean, with 450,000+miles my cylinders still look as they did from the factory, no scouring whatsoever no up and down ring lines that are common, my valves have no sludge period no carbon build up anywhere on the motor, you wouldn't believe it from the look of the outside of the motor but the inside looks, sounds, and performs as it did in 1988 if not a little better with all my grounded wires to the block, and 108 octane is $4.76 usd per gallon, and I get ether free from the shop lead he's an NHRA and NHRDA racer and his sponsors want him running ether for a cleaner burn which in turn results in a longer lasting motor. Btw this whole build isn't permanent, I have a pal who duplicates the vg30 block out of aluminum and makes diesel motors rated at 1,900 lb-ft of torque and 700 hp and he's going to hook me up with a killer deal. Yes that's right a v-6 diesel nearing 2k of torque.

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  • 2 years later...
  • 3 weeks later...

I could see 30MPG as I can reliably get 25MPG in my 86.5 V6 4x4 hardbody with long tubes, stock cat back and 10w30 Castrol Edge. I do have a HG41 rear end so I turn just over 2500RPM at 70MPH. My fuel mileage tanks quick in the city though. Boy will it eat fuel if I let it.

Edited by deerhurst
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I recently spoke to Mr.Conners .. he has an 87 Nissan gave him with every part he ever made on it .. looks good... mr conners has spare parts and the carb parts but he explained a few reasons why he wouldn't part with em and wished he kept this side of his empire but back then no one expressed interest in these trucks like now .. but he has a lot of stuff laying around.

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