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 (http://www.summitracing.com/parts/SUM-700203/)
TV CABLE bracket (http://www.summitracing.com/parts/TCI-376700/)

Links for Holley carbs.
Throttle lever (http://www.summitracing.com/parts/HLY-20-121/)
TV Cable bracket (http://www.summitracing.com/parts/HLY-20-95/)

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.

[Bad Bowtie 91]

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?

An adapter plate for the carb you plan to run and a lock-up kit.
The adapter plate keeps the TV cable at the correct length for propper shifting, I'm not running a torque converter lock-up and haven't for over 13K miles, my trans shifts fine also.
The converter only locks up in 4th gear anyway, it's just for gas savings I guess.

TV cable bracket for Carter & Edelbrock carbs.
http://www.summitracing.com/parts/TCI-376700/

TV cable bracket for Holley carbs.
http://www.summitracing.com/parts/HLY-20-95/

[1ugly88]

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.

any pics of this assembled? am going to be carbing mine shortly and would like to have all the parts on hand before i start

[cttandy]

any pics of this assembled? am going to be carbing mine shortly and would like to have all the parts on hand before i start

I assembled it all to see how it would look and put it up.

Well, I have changed my mind and I am going with a LS engine in my truck. I could make you a good deal on everything.

[1ugly88]

I assembled it all to see how it would look and put it up.

Well, I have changed my mind and I am going with a LS engine in my truck. I could make you a good deal on everything.

you have a pm

[cttandy]

This is what the fuel line adapters look like on the regulator, as requested. It was a whopping 18 degree out so the braided lines would co-operate for me.

http://i332.photobucket.com/albums/m341/cttandy/Short%20GMC/IMG-20101214-00060.jpg
http://i332.photobucket.com/albums/m341/cttandy/Short%20GMC/CrossPlains-20101214-00061.jpg
http://i332.photobucket.com/albums/m341/cttandy/Short%20GMC/IMG-20101214-00065.jpg

[1badbowtie4x4]

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.

i don't believe the tbi distributors had a vacuum advance tho, which doen't mean that it wont run but just that it wont run as well.

[Bad Bowtie 91]

^ exactly

Just because you can, doesn't mean you should...

[350CHEVYROB]

when i swapped out my tbi all i did was just unplug all the sensors like for the injector,IAC,MAP,and moved them to the side and keeped the dizzy all hooked up.although i had a 4l60e i just made a bracket so i could mount it to the carb and still have the tps shift the tranny.i really didn't notice any problem with the dizzy's and it not advancing like it should.it all ran and shifted as if i had the tbi unit on

[350CHEVYROB]

This is what the fuel line adapters look like on the regulator, as requested. It was a whopping 18 degree out so the braided lines would co-operate for me.

http://i332.photobucket.com/albums/m341/cttandy/Short%20GMC/IMG-20101214-00060.jpg
http://i332.photobucket.com/albums/m341/cttandy/Short%20GMC/CrossPlains-20101214-00061.jpg
http://i332.photobucket.com/albums/m341/cttandy/Short%20GMC/IMG-20101214-00065.jpg

where you able to run the stock fuel pump for the tbi with that style regulator .

[1ugly88]

where you able to run the stock fuel pump for the tbi with that style regulator .

yes, to run the stock pump you need a return style regulator or you will burn the pump up.

[mjealey]

Hey, I am just curious where are you mounting your fuel pressure regulator in the truck?

[cttandy]

I was going to mount mine above the distributor on the firewall. Plenty of room around it and the good access to the adjustment and the guage was visible. With it being so cold out, I couldn't get the hoses up there to take a picture of it. It could be mounted virtually anywhere on the firewall however.

[tnkhackworth]

i have a 96 vortec 4.3 i am replacing with an older carbed 350 how are yall mounting your ac and alternator and things. the heads i have dont have to 3 holes for the accessory's like my vortec did

[1badbowtie4x4]

you might need the aluminum serpintine set up off a 350 tbi motor thats what i run.

[jwh432]

when i swapped out my tbi all i did was just unplug all the sensors like for the injector,IAC,MAP,and moved them to the side and keeped the dizzy all hooked up.although i had a 4l60e i just made a bracket so i could mount it to the carb and still have the tps shift the tranny.i really didn't notice any problem with the dizzy's and it not advancing like it should.it all ran and shifted as if i had the tbi unit on

Rob, did you do the carb swap in your 95 4x4? I have a 94 z71 that I am about to swap in a carb and nv4500 for my tbi and 4l60e.

I know I should not have any computer issues with the tranny or the carb setup by doing away with the ecm altogether, but I thought I read somewhere that the signal to activate the front diff. goes through the ecm. did you encounter any issues like that, and if so how did you get past them?

Were there any other trouble spots I should know about? The swap sounds straight forward enough, but I have been trying to plan for any unforseen circumstances. Any advice you might have would be appreciated.

-j

[350CHEVYROB]

Rob, did you do the carb swap in your 95 4x4? I have a 94 z71 that I am about to swap in a carb and nv4500 for my tbi and 4l60e.

I know I should not have any computer issues with the tranny or the carb setup by doing away with the ecm altogether, but I thought I read somewhere that the signal to activate the front diff. goes through the ecm. did you encounter any issues like that, and if so how did you get past them?

Were there any other trouble spots I should know about? The swap sounds straight forward enough, but I have been trying to plan for any unforseen circumstances. Any advice you might have would be appreciated.

-j

well if you have a 4l60e in your truck right now and you rip the EMC out of the truck. your 4l60e with not shift right and you'll end up blowing up the tranny within days .the TPS sensor and ECM is what tells the tranny when to shift without that it won't work

thats why it built a lil bracket on the side of the carb to bolt up a tps sensor to trick the tranny thinking the tbi unit is still there. i didn't disable the emc just unhooked some sensors like the injc,map,IAC, and keeped the rest hooked up .run great shifted fine and had a lot more power than the 670 tbi holley i had on it before i did the swap.

heres some pics of my setup
http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs254.snc4/40028_135560869819940_100000980835233_170846_66786 35_n.jpg
http://sphotos.ak.fbcdn.net/hphotos-ak-snc4/hs280.snc4/40339_135560756486618_100000980835233_170844_43320 07_n.jpg
http://sphotos.ak.fbcdn.net/hphotos-ak-snc6/hs022.snc6/165196_165948410114519_100000980835233_315306_3789 606_n.jpg

[jwh432]

i'm doing away with the auto and swapping in a nv4500 (5 spd granny) so I don't have to worry about the tranny.

that does answer my question about the other computer controlled items though. I was just talking to a buddy and we came up with the same solution. I had thought about ripping out the computer altogether, but If I just disconnect the stuff I don't need for the carb + manual tranny setup and let the computer run all its other routines, it sounds like everything else that may run through the computer will be unaffected. thanks for the response.

-j

[MREYNA]

Have u done the swap? any pics

[La 90sierra]

well i wanna do my truck carb'd. i've read a lot of good thing about it but what is your mpg. i know it will suffer drastically. how bad??

[MREYNA]

I'm getting 14 mpg.mine is a 350.ext cab,and has headers.n crank pulley,and a 650 double pumper carb.
http://i703.photobucket.com/albums/ww38/mreyna3879/7cd39606.jpg
.it used to do 10 mpg when it had 3000 stall n lunati cam..what part of texas r u from bro?

[MREYNA]

I'm getting 14 mpg.mine is a 350.ext cab,and has headers.n crank pulley,and a 650 double pumper carb.
http://i703.photobucket.com/albums/ww38/mreyna3879/7cd39606.jpg
.it used to do 10 mpg when it had 3000 stall n lunati cam..what part of texas r u from bro?

[La 90sierra]

i'm from weslaco bro. i got an account on rgvtrucks too. la nighty5er. well mine was wrecked so i got me another one. rvsb 90 silverado. 350. did you ever find your blue ex-cab

[MREYNA]

Cool cool .Nah I never found the truck.but that's how it is.ratas everywhere bro...dam i just got this acct bro.who else is in here ?

[La 90sierra]

what did you get now. i found naranjas and julio. the one with the slammed white sierra. the one that had the obs stepside. i just dont know what their usernames are.

[La 90sierra]

http://i816.photobucket.com/albums/zz82/gsalinas88/IMG147.jpg

http://i816.photobucket.com/albums/zz82/gsalinas88/IMG149.jpg

http://i816.photobucket.com/albums/zz82/gsalinas88/IMG148.jpg

this is what i got myself. it was a faded red color. its primed now. waiting to paint it. wanna carb it out. thats why i subscribed to this thread. so i wont loose the info.

[MREYNA]

I'll help u out bro .just pm me ur #

[La 90sierra]

will do. just gotta get the coins first. i've spent a couple hundreds getting it up to date. damn it was way out of timing and so forth bro. its running better than what it was. but thats what i wanted. a project/daily driver.

[chevyfan87]

just because ive done it before... when swapping from tbi to a carb the earlier tbi blocks still had provisions for a mechanical ppump. i did the swap on the old 92 and just pulled the fuel pump fuse and installed a mechanical. the pump had no problem pulling through the stock one. never ran short on fuel

[jfsjr92]

my 95 k1500 z71 i am buying is carbed already w a 350. does a TBI 350 and Carb 350 have the same exhaust pattern?

[cttandy]

yes, they should be the same. The port shape might be a little different, but the manifolds will bolt up.

[jfsjr92]

cool, it has longtube headers on it but its in the way of front driveshaft so i need to replace them w shortys

[JaredW]

just because ive done it before... when swapping from tbi to a carb the earlier tbi blocks still had provisions for a mechanical ppump. i did the swap on the old 92 and just pulled the fuel pump fuse and installed a mechanical. the pump had no problem pulling through the stock one. never ran short on fuel

did your gas gauge still work

[farmboy1466]

I'm getting 14 mpg.mine is a 350.ext cab,and has headers.n crank pulley,and a 650 double pumper carb.
http://i703.photobucket.com/albums/ww38/mreyna3879/7cd39606.jpg
.it used to do 10 mpg when it had 3000 stall n lunati cam..what part of texas r u from bro?

What gears are you running?

Also I have some questions on this subject as well. I've heard from some that if you do the carb swap, your computer can throw too many codes and make the transmission not shift right. Is this true?
Also, when you swap from a 4L60E tranny to a 700r4 tranny, how do you get your speedo to work?

[dpmalibu]

I need to know that very question. when swapping from a 4l60E to 700 R4 how do you get the speedo to work. Sorry if I hi-jacked your thread.

[cttandy]

Should just plug in.

[farmboy1466]

I don't know much about the 700r4. Does it have the vss just like the 4L60E? If so, does the computer run the speedo in the 88-92 (or whatever the last year they used the 700 was)?

[cttandy]

Depends on what year 700 you use. But the right year will have a vss as well.