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#1 |
Registered User
Join Date: Jul 2014
Location: Kansas
Posts: 53
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Ditching the TBI for carb...
I have an 87 Silverado 4x4 with the 350 tbi and lock up 700r4. Trans was rebuilt and beefed up a couple years back, but the motor is getting in need of a freshen up. With that said if I tear this thing out this summer I'd like to dump the TBI and build something up a little that would give more smiles per miles per say. Dug around the last 45 minutes on the web with not much solid advice besides don't do it.
Soooo what does a guy need to know? Another question is the 700r4 in the 87 computer controlled? Would I be better to swap say a 350/400 turbo in, if so how extensive is that? Thanks in advance! |
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#2 |
Registered User
Join Date: Dec 2011
Location: Yuma Arizona
Posts: 1,526
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Re: Ditching the TBI for carb...
I'm assuming you don't have emission checks there? If so, how you going to get around it?
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#3 |
Registered User
Join Date: Jul 2014
Location: Kansas
Posts: 53
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Re: Ditching the TBI for carb...
No emissions check.
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#4 |
Registered User
Join Date: Nov 2009
Location: Haines City FL
Posts: 461
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Re: Ditching the TBI for carb...
I also advise against it, unless it is trashed and not working. I think you will not be gaining anything if you do dump the Tbi. Sure, you can tune, and do all kinds of stuff to carbs, but some engineer took all the guesswork out of it and put tbi.
Oh and the 700 is not computer controlled. |
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#5 | |
Registered User
Join Date: Jul 2014
Location: Kansas
Posts: 53
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Re: Ditching the TBI for carb...
Quote:
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#6 |
Registered User
Join Date: Jan 2014
Location: Swaledale, IA
Posts: 485
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Re: Ditching the TBI for carb...
I want to add to the above about the 700r4 - the computer does control part of it - the electronic converter lockup is controlled by the ECM.
Keith S may know more about you would lose/keep when you remove the TBI system. I considered it when I swapped to a rebuilt 350 with all different parts since TBI is very picky on what it likes. In the end I didn't want to lose my Cruise, A/C high idle & 700r4 Lockup which all run through the ECM and talk to the TBI system to get their parameters on when to do things. I went with the Dynamic EFI system which seems to work pretty well. I added the Holly TBI in place of stock as well which normally will give fits on the stock ECM, but the Dynamic EFI system can control it - it works very well. |
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#7 |
Registered User
Join Date: Feb 2012
Location: Morgantown, Wv
Posts: 294
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Re: Ditching the TBI for carb...
While I'm not sure on the 700r4 stuff. But I got rid of my tbi for a quadrajet and in my opinion it was one of the best things I've ever done to this truck. You'll need an intake, a carb of course, HEI distributor, and a fuel pressure regulator. My A/C still works, don't have cruise so not sure on that.
Don't worry I also had a lot of tbi Lovers telling me what a horrible idea removing the tbi was.
__________________
87 V20, Vortec 350, Sm465, Np205, Dana 44, 14bff 4.10's |
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#8 |
Registered User
Join Date: Jan 2014
Location: Swaledale, IA
Posts: 485
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Re: Ditching the TBI for carb...
I should clarify - the A/C will still work, but the high-idle when its on will be lost.
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#9 | |
Registered User
Join Date: Apr 2001
Location: DALLAS,TX
Posts: 21,964
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Re: Ditching the TBI for carb...
Quote:
That being said, I wouldn't necessarily just throw on a carb though. There has been recent development by multiple manufacturers for retrofit TBI set-ups that adapt to various combos, self tune using technology developed long after TBI's were new, and that don't cost an arm/leg.
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67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... Cubic inches is like Indiana Jones with a cheap pistol. |
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#10 |
Registered User
Join Date: Apr 2001
Location: DALLAS,TX
Posts: 21,964
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Re: Ditching the TBI for carb...
Carbs had AC idle solenoids that would adjust the idle automatically when the AC is in use. It was available since the early 70's.
__________________
67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... Cubic inches is like Indiana Jones with a cheap pistol. |
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#11 | |
Registered User
Join Date: Jul 2014
Location: Kansas
Posts: 53
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Re: Ditching the TBI for carb...
Quote:
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#12 |
Registered User
Join Date: Feb 2012
Location: Morgantown, Wv
Posts: 294
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Re: Ditching the TBI for carb...
Yup, pretty much. There were a couple of wires I had to splice together for the fuel pumps. If I'm remembering correctly.
__________________
87 V20, Vortec 350, Sm465, Np205, Dana 44, 14bff 4.10's |
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#13 |
Registered User
Join Date: Jan 2010
Location: Kansas City, Mo
Posts: 284
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Re: Ditching the TBI for carb...
Im pushing 320hp and 400tq from my 87tbi 350 silverado. Have a comp cam 90350 truck avenger camshaft,454 throttle body with 90pph injectors and 18psi fuel pressure springon a bored to match Edelbrock intake manifold, .060 over with 9.8:1 compression, and stock 89 heads. Yes i am limited to about 5000rpm because of the heads but the biggest problem with the tbi engines is the pathetic stock camshaft. Lots of low end torque amd very fun to drive as well as good as a daily driver, reliable.
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Thank a Veteran. They have sacrificed more than you will ever know! 2003 Chevy Z71 Tahoe 190,500 miles 2002 Chevy Silverado 1500 4x4 230,000 miles 1987 custom built Silverado 4x4 435,764 miles 1985 K5 Blazer 396 bb 4x4 project 1982 K5 Blazer Silverado 4x4 519,348 miles |
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#14 |
driving is in my blood
Join Date: Dec 1999
Location: Mesa AZ
Posts: 5,720
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Re: Ditching the TBI for carb...
Swap the carb on, wire in the lockup for the convertor manually or using a bowtie overdrives setup like I did with my 200-4R and it locks up in 4th automatically.
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-78 c10 short/step: 388cid, M20, 5/5 drop, lots more. Playtoy and first vehicle. -98 c1500 x-cab: 5.7L, 17" rims, 5/6 drop, flowmaster, helper bags,NBS rear disk brakes. -02 Suburban 4x4: leveled front -CBR600F4i, CBR600RR, CBR1000RR, and standup skis DISCLAIMER: I cant spell for the life of me. |
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#15 |
Registered User
Join Date: Dec 2011
Location: Regina, SK, Canada
Posts: 622
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Re: Ditching the TBI for carb...
Under 400 hp - stick with the tbi. It is a great setup, if already equipped I would spend the time to get it working for you. Just my 2 cents.
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1979 Chevy Dually Crew 4X4 454, D60 Tru-trac, D70 Detroit Locker, 3.73, 4L80E/NP205 1971 GMC 3/4 Ton 4X4 |
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#16 |
Registered User
Join Date: Nov 2016
Location: Dayton Texas
Posts: 67
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Re: Ditching the TBI for carb...
here is my two cents worth,
Started with a stock 1991 4300 pound Chevy truck with TBi, and about 16 mpg, then added injector spacer, and throttle body spacer, and a super hot coil, a set of headers, it went from the 16/17 to 21 to 24 miles per gal. on 89 octane, for what ever reason it seemed the coil made the biggest difference, every other week i drove from Houston to Denton Texas, at around 300 miles one way, so to experiment I would drive with windows down and A/C off, with factory coil, then hook the hot coil up, with out A/C and then with..ect ect.. the best thing about it was that there was no choke worries on a cold day, and it was super reliable, and idled smooth,... I have a stock 1981 Chevy with 4 barrel carb, and other than the killer sound it makes when you flip the breather over, it never can match my 91 for reliability and fuel mileage, |
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#17 |
Special Order
![]() ![]() Join Date: Nov 2004
Location: Mt Airy, MD
Posts: 85,859
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Re: Ditching the TBI for carb...
I have no complaints about Quadra-Jets or TBI. That's why I leave what came on the vehicle.
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"BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~ |
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