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swapping from tbi to carb

This is a discussion on swapping from tbi to carb within the Technical / Maintenance forums, part of the General Discussion category; im wondering if anyone can tell me how hard it is to swap from tbi to carberated.im swapping the whole ...

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    swapping from tbi to carb


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    im wondering if anyone can tell me how hard it is to swap from tbi to carberated.im swapping the whole engine and just wondering what ill have to change or add.i heard something about the fuel tank.maybe the fuel pump but not sure.any help would be great.thank you.

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    Built, not bought. Bad Bowtie 91's Avatar
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    re: swapping from tbi to carb

    You would have to give us some kind of info on your truck, what year, trans, what motor is in it now, would be really helpfull.

    Also, there is a carbed section, and this has been covered extensively...

    http://lmgtfy.com/?q=chevrolet+1500+tbi+to+carb+swap
    Last edited by Bad Bowtie 91; 12-01-2010 at 07:13 AM.
    91 ECSB, 305 bored .30 over, Flat top pistons, Summit Racing 272/282 cam, Holley carb, Edelbrock intake, Accel HEI dizzy, 801 heads, 700R4, 3.42's open.


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    re: swapping from tbi to carb

    The fuel pump for TBI puts out higher pressure/flow so the injectors can spray a mist (hence, fuel pressure regulator and fuel return line). Depends what carb setup you're trying to put on there, but you'll need an adapter plate to get it bolted onto the intake manifold. Possibly an aftermarket bracket for the transmission TV cable.

    why bother changing to carb? Guys will claim either system as superior. I think tbi rocks, because it's so easy to maintain and troubleshoot. No sense throwing away cash to get rid of something that's good to begin with.

    Edit: see above post. use google.
    Last edited by helo; 12-01-2010 at 07:12 AM.

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    re: swapping from tbi to carb

    well the motor that is in it is a 350 and im not sure about the tranny.but both of them are way tired and need to be replaced and i have a stong motor and tranny sitting on the shop floor waiting to go in there.the truck is an 1987.it was a r10 from factory and some1 swapped it over to v8.

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    Registered User mjealey's Avatar
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    re: swapping from tbi to carb

    All right mine is an 87 and I swapped over to carb, and it is by far the best thing I have done. I am going to give you the easy way.

    1. You need a fuel pressure regulator. TBI fuel pressure is around 13 PSI I believe, carbs like it around 6 PSI. Here is the one most people run, you have to make sure it has a return line back to the tank:

    http://www.summitracing.com/parts/HLY-12-704/


    2. Next thing you need is a carb, to keep it simple I would suggest this one:

    http://www.summitracing.com/parts/EDL-1406/

    It has an electric choke on it, and my truck starts no problem in below freezing weather. That is the knock on going TBI to carb.

    3. You need a new intake. This is one of the most expensive, but I like it best and it works really good.

    http://www.summitracing.com/parts/EDL-2601/

    4. You will need a new HEI distributor, make sure it is a vacuum advance HEI distributor. This one should work just fine:

    http://www.summitracing.com/parts/SUM-850001R/

    http://www.summitracing.com/parts/MSD-8362/


    I took mine a step further. I pulled the tanks in my truck and put in the fuel sending unit designed for a carb. This gets rid of the electric fuel pumps in the tank. I actually went old school and put on a Holley mechanical fuel pump. I like it because it is easy to change. Or some people run an inline electric fuel pump and mount on their frame rail. Then run your line straight into your carb. This gets rid of the fuel pressure regulator on the firewall, and looks a lot cleaner in my opinion. Plus, if the fuel pump ever goes out, it is a lot easier to replace then pulling the fuel tank. Your trans should be fine. The TV bracket fits no problem on the edelbrock and will hook right into the carb.
    1987 Chevy 4x4, 6" Skyjacker (all spring), 35" Super Swampers, Dana 60 (front) GM 14-Rear 4.56 gears, TH400, Built 355.

    2007 Chevy 2500HD LT, Crew Cab, Duramax

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    re: swapping from tbi to carb

    Quote Originally Posted by mjealey View Post
    All right mine is an 87 and I swapped over to carb, and it is by far the best thing I have done. I am going to give you the easy way.

    1. You need a fuel pressure regulator. TBI fuel pressure is around 13 PSI I believe, carbs like it around 6 PSI. Here is the one most people run, you have to make sure it has a return line back to the tank:

    http://www.summitracing.com/parts/HLY-12-704/


    2. Next thing you need is a carb, to keep it simple I would suggest this one:

    http://www.summitracing.com/parts/EDL-1406/

    It has an electric choke on it, and my truck starts no problem in below freezing weather. That is the knock on going TBI to carb.

    3. You need a new intake. This is one of the most expensive, but I like it best and it works really good.

    http://www.summitracing.com/parts/EDL-2601/

    4. You will need a new HEI distributor, make sure it is a vacuum advance HEI distributor. This one should work just fine:

    http://www.summitracing.com/parts/SUM-850001R/

    http://www.summitracing.com/parts/MSD-8362/


    I took mine a step further. I pulled the tanks in my truck and put in the fuel sending unit designed for a carb. This gets rid of the electric fuel pumps in the tank. I actually went old school and put on a Holley mechanical fuel pump. I like it because it is easy to change. Or some people run an inline electric fuel pump and mount on their frame rail. Then run your line straight into your carb. This gets rid of the fuel pressure regulator on the firewall, and looks a lot cleaner in my opinion. Plus, if the fuel pump ever goes out, it is a lot easier to replace then pulling the fuel tank. Your trans should be fine. The TV bracket fits no problem on the edelbrock and will hook right into the carb.
    thank you very much.thats all i wanted was a simple explaintion on it.not some smart ass coment.i googled it before but i wanted to hear from ppl that have done it before. what about the wiring?no changes there? what im doing is pulling my motor out of the buick regal.its not a buick motor its a 350 with lots of go.the whole top end is edelbrock and i got a msd distributer in it. im also putting my tranny in to cause the tranny in the truck is killed and the one in my car shifts good and hard.

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    re: swapping from tbi to carb

    That response assumes that you have the 700R4 transmission, and while it's mostly correct. If you have a 4L60E trans, it's not as simple, It's computor controlled
    You need to tell us what year and model your truck is, 2wd, 4wd, 2500, 1500...
    I swapped mine awhile back, and wouldn't mind helping, but you got to tell us a little info on the truck.

    You can also use the intake fuel pump, just get the Holley 12-803BP fuel pressure regulator instead of the one in that link and you won't have to run new fuel lines.
    91 ECSB, 305 bored .30 over, Flat top pistons, Summit Racing 272/282 cam, Holley carb, Edelbrock intake, Accel HEI dizzy, 801 heads, 700R4, 3.42's open.


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    re: swapping from tbi to carb

    im not sure what year the engine is cause it was a 6 banger truck from factory.its an 1987 chev shorty. the engine is newer then the truck.the valve cover bolts are on top the cover not on the sides.2wd 1\2 ton truck.and as for the tranny im not to sure but some1 said it has an electronic kick down on it thats not hooked up if that tells you anything.

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    Registered User mjealey's Avatar
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    re: swapping from tbi to carb

    I am about 95% sure you have the 700r4 then. Look under the truck at the pan. The pan for the 700r4 is perfectly square. If it is a 700r4, all of the shifting is controlled by what is called a TV cable. It runs up the transmission and is connected on a mount that is on the drivers side at the rear of the intake. Then runs up and is connected to the TBI unit, at the bottom under the throttle cable. The TV cable also controls the kick down. You wouldn't make it very far at all if the TV cable wasn't hooked up and the truck wouldn't shift. So you should be able to get the truck to kickdown. The TV cables are picky and need to be properly adjusted.

    My truck shifted fine when I converted to carb. The only thing I had to do was get a lockup kit for the torque converter. If you switch to a carb and don't do this your torque converter won't lock up.

    I am pretty sure about all of the above, somebody back me up on all of this?
    1987 Chevy 4x4, 6" Skyjacker (all spring), 35" Super Swampers, Dana 60 (front) GM 14-Rear 4.56 gears, TH400, Built 355.

    2007 Chevy 2500HD LT, Crew Cab, Duramax

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    Registered User mjealey's Avatar
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    re: swapping from tbi to carb

    I am about 95% sure you have the 700r4 then. Look under the truck at the pan. The pan for the 700r4 is perfectly square. If it is a 700r4, all of the shifting is controlled by what is called a TV cable. It runs up the transmission and is connected on a mount that is on the drivers side at the rear of the intake. Then runs up and is connected to the TBI unit, at the bottom under the throttle cable. The TV cable also controls the kick down. You wouldn't make it very far at all if the TV cable wasn't hooked up and the truck wouldn't shift. So you should be able to get the truck to kickdown. The TV cables are picky and need to be properly adjusted.

    My truck shifted fine when I converted to carb. The only thing I had to do was get a lockup kit for the torque converter. If you switch to a carb and don't do this your torque converter won't lock up.

    I am pretty sure about all of the above, somebody back me up on all of this?
    1987 Chevy 4x4, 6" Skyjacker (all spring), 35" Super Swampers, Dana 60 (front) GM 14-Rear 4.56 gears, TH400, Built 355.

    2007 Chevy 2500HD LT, Crew Cab, Duramax

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    re: swapping from tbi to carb

    Quote Originally Posted by 87shorty View Post
    im not sure what year the engine is cause it was a 6 banger truck from factory.its an 1987 chev shorty. the engine is newer then the truck.the valve cover bolts are on top the cover not on the sides.2wd 1\2 ton truck.and as for the tranny im not to sure but some1 said it has an electronic kick down on it thats not hooked up if that tells you anything.
    If it's a 700R4 trans, without the cable hooked up it won't shift properly.
    Sorta sounds like you might have a TH350 trans. Does your trans have OD? Or do you have a black cable coming from the trans to the TBI unit?


    Either way here's how to do the swap.
    Get a bypass fuel pressure regulator, Summit part # HLY 12-803BP. And that will take care of the fuel.
    That should pretty much complete your swap, just use the pink and white wires from the distributor to power the HEI dizzy ( pink is power, white is the tach feed)
    swap over the oil pressure sending unit( sits right beside the dizzy) and water temp sensor ( on the drivers head) and all your factory gauges will work like factory.
    91 ECSB, 305 bored .30 over, Flat top pistons, Summit Racing 272/282 cam, Holley carb, Edelbrock intake, Accel HEI dizzy, 801 heads, 700R4, 3.42's open.


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    Built, not bought. Bad Bowtie 91's Avatar
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    re: swapping from tbi to carb

    Quote Originally Posted by mjealey View Post
    I am about 95% sure you have the 700r4 then. Look under the truck at the pan. The pan for the 700r4 is perfectly square. If it is a 700r4, all of the shifting is controlled by what is called a TV cable. It runs up the transmission and is connected on a mount that is on the drivers side at the rear of the intake. Then runs up and is connected to the TBI unit, at the bottom under the throttle cable. The TV cable also controls the kick down. You wouldn't make it very far at all if the TV cable wasn't hooked up and the truck wouldn't shift. So you should be able to get the truck to kickdown. The TV cables are picky and need to be properly adjusted.

    My truck shifted fine when I converted to carb. The only thing I had to do was get a lockup kit for the torque converter. If you switch to a carb and don't do this your torque converter won't lock up.

    I am pretty sure about all of the above, somebody back me up on all of this?
    You're pretty much dead on, execpt that the 700R4 and the 4L60E use the same 16 bolt square pans...

    I haven't done the torque converter lock up kit yet, but after 20K miles on my carb swapped motor it still shifts perfectly. I might do it one day.....
    91 ECSB, 305 bored .30 over, Flat top pistons, Summit Racing 272/282 cam, Holley carb, Edelbrock intake, Accel HEI dizzy, 801 heads, 700R4, 3.42's open.


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    Re: swapping from tbi to carb

    anybody have a link to the TC lockup kit they prefer im converting to carb in my mudder and hadn't herard anything about this
    92 K1500 6.5" stage II DC lift, Homemade shackle flip, ORD Shackles, 2" BL, 37" KM2s. carb'd mildly built 383 stroker, SAS/14bsf underway!!!!!!!!

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    91 ECSB, 305 bored .30 over, Flat top pistons, Summit Racing 272/282 cam, Holley carb, Edelbrock intake, Accel HEI dizzy, 801 heads, 700R4, 3.42's open.


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    Re: swapping from tbi to carb

    BB 91,
    question sir, i just completed the same swap, (87 chevy V10 350), wiring the in tank pump & using the 12-803BP, fuel press at 5psi. fuel out vent tube. cleaned, changed n & s, float, adjusted float,. set reg to 3psi. same problem..just swapped carbs, dbl checked press (3psi), same...fuel out vent tubes. any ideas? i'm running out of them.
    thanks for any response. these forums & all you guys are the bomb.
    thanks again
    wildb

    (not sure if it makes a difference, but all my testing of fuel press & carb problems are without truck running)
    Last edited by wildb; 03-30-2013 at 06:11 PM.

 

 

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