TBI to Carbed: What it takes.

[2LNBLKTOP]

I have a 305 tbi in my 1993 chevy and it smokes like a bitch. Changed the valve seals and it still smokes like a bitch. It runs great idles and drives great but still smokes like a BITCH. I can't find a tbi to replace it that's worth the money 305 or 350. So I decided to drop in my 383 stroker but I don't know what all it takes. If u know let me know and in a hurry please.

[Bad Bowtie 91]

There is a few threads on this already, but I'll type it again.
What trans do you have, 4L60 or 700R4?

NEEDED PARTS: Older HEI distributor, Fuel pressure regulator with a return line ( Holley 12-803BP or Mallory 4309) Carbed intake for your motor, Carb.
If you have a 700R4, you might be able to use the TV cable bracket off your old TBI motor, or buy the bracket from Summit for your specific carb.

Links for Edelbrock, Carter, Quadrajet carbs.
Throttle lever for Edelbrock carb
TV CABLE bracket

Links for Holley carbs.
Throttle lever
TV Cable bracket

Now if you have the 4L60, you'll have to use a TPS on the carb.

Step 1: you'll have to use a fuel pressure regulator with a return line if your gonna use the in-tank pump, without a return line you'll burn up the pump fairly quick.
I'm using a Holley 12-803BP $80. shipped through Summit.

Step 2: Hei distributor, use the pink & white wires that power your coil to power the HEI.
Cut the wires going to your coil, Pink = power, White = Tach. and attach them to the HEI dizzy.

Step 3: keep your Oil pressure, water temp, alt, and AC wiring and hook up like normal and all your factory gauges will function the same as stock.

Step 4: remove all unused wiring like O2 sensors, TBI, and anything else not being used and heat shrink them.

Step 5: drive it like you stole it.

It's a really simple swap and I'm sorry for the novel but that should answer your question.

[2LNBLKTOP]

I have a 5 speed, tranny but can convert to automatic if need be. IThe motor I'm runnin is a 350 4bolt main block bored .030 over, sportsman2 2.02 heasds roller rockers and studgirdles and a compcams 2 cam that will have to be toned down. The carb I'm runnin is a proform 750 double pumper.

[Bad Bowtie 91]

With your 5 speed you wont have to worry with the brackets.

Just grab a fuel pressure regulator and a HEI distributor and your set.

[SierraDan]

Have you tried ebay for a TBI unit or any local pick and pull yards? If you have no luck there contact TBI Chips, shoot him an e-mail to see what he recommends. I see no point in going backwards as far as fuel delivery technology.

[rickg86]

hey, my builder says i wont need a new distributor doing this swap. is that true? i have a 91 ecsb with 305 tbi.

[85-bowtie]

I ran the factory tbi style distributor on my 90 that was carbed. No problems at all. I really don't see the need for the older HEI unit myself.

[rickg86]

Oh okay. Everywhere I read its required. So I just wanted to know if it was required so I could factor it into my already tight budget. Wich is going great, todays scores, 60$ used shorty headers and 60$ performer intake. Both used/good condition. (Canadian prices)

[speedracer326]

I'm doing the carb thing on the Crown Victoria and it really makes me appreciate my EFI. That's definitely the last time I do an EFI to carb swap, especially now that I know how to tune EFI myself.

[SierraDan]

Something i've been wondering: you can change stuff like transmission shift points with a tune if you have EFI, but how would that be changed if you have a carb? How are tranny shift points controlled with no computer, is it mechanically set in the tranny itself, or like vacuum controlled? How would you change it?

[speedracer326]

For a 700R4 you buy a weight set for the governor to set WOT and part throttle shifts. There's a heavy and light weight inside it. You still don't have as much control with the 700R4 as you do with a 4L60E.

[stltwinturbo]

does anyone have pics of they setups

[mjealey]

What does everybody do with all the TBI wires if they convert to carbs? Just leave them in the engine compartment or what?

[cttandy]

Everyone says to cut them out. I am leaving mine, but going to attempt to hide the unused wires some how. I am thinking of trying to use a small plastic box or something.

The only reason I am leaving mine, I might want to change it to a TBI 454 down the road when I get bored with the 350.

[mjealey]

Yeah i thought about trying to hide mine, but it is hard to hide them under the hood. I am currently trying to cut mine out right now. Bought a wiring schematic, but I am affraid to go cutting stuff as some is hooked in with the fuel pump, and I am affraid to cut too much and then I have a problem.

[creechkilla]

Just to throw in my two cents, I have a '92 reg can step side and have been through everything you can imagine. Originally a 4.3l v6 5sp, I did a complete conversion to 350 700r4. No corners cut, I replaced everything to make it like stock except performance mods along the way. I change the computer to an EBL Flash, (Flashable EPROM USB chip insert), pulled a wiring harness out a wrecked 93, Holley TBI, small cam, MSD ignition, exhaust, headers, etc. I have a way longer list but I'll keep it short so I can get to the point. I tuned it several times and don't get me wrong, it ran pretty strong. Now is my point. If you want performance, dump the TBI. It's a complete waste of money unless you want to have a "stock" style setup. I've now pulled that motor and am near complete with the new setup. Carbed and blown 383. I'm in the middle of cleaning the wires out from under the hood simply because I'm very picky with cosmetics. I've had this truck since '98 and my receipts are over $40k. Roughly $10k of that was to peak out a rather disappointing TBI 5.7. Other costs were paint jobs, suspension, interior work, and front end upgrades (I've had two phantom grilles, inserts, new and old style clips, and now a '00 Denali clip with '02 sierra bumper.) If you have any questions regarding motor or tranny swaps, I'm sure I can help. As far as keeping the wires for a TBI 454, it would be cool but way more expensive and less HP than carb. Main advantage with the TBI would prolly be better MPG, or like I said, a "stock" style setup. Sorry about the long reply, but I do custom car work for living and don't mind helping you guys out. My expense loss and experience can help you save a lot of money.

[gimmel1]

I was wanting to gp carbed with my 94 step side with a 4l60e i know i need a tps but how do i attach it to the carb and what else do i need???

[creechkilla]

I'm not too sure on the 4l60e, but that tranny is basically an electronic 700r4. You might be able to pull the electronics out of it and give a throttle valve cable and hydro lockout. Or, there might be a company that makes a computer or harness to retain electronics only for the tranny itself. Check with TCI or Painless, that would be my first choice. Sorry I can't be of anymore help.

[1992Jim]

Thanks. You answered a lot of the questions I had when I starting checking out this forum. Your thread doesn't mention what's needed if you have a 700R4 trans. Can you tell me if any mods need to be done for the tranny in this swap?

[cttandy]

OK, thought I would share for other people. My truck has the stainless flex fuel lines. After playing around with different adaptors for the lines, I came up with this.

http://www.summitracing.com/parts/HLY-12-803BP/
http://www.summitracing.com/parts/EAR-916166ERL/ x2
http://www.summitracing.com/parts/EAR-9894DBHERL/
http://www.summitracing.com/parts/EAR-9894DBJERL/

My regulator (didn't get it from summit) came with a fuel line adapter for the feed to the carb. Hope this helps someone in the future.