Redneckmudslinger
Registered Member
hi everyone i have a 88 gmc jimmy sierra classic it has a 350tbi with fuel injection system on it and i wanna to known how to swap it out with a 4 barrel carburetor thanks everyone
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
tbi to carburetor swap help
- Thread starter Redneckmudslinger
- Start date
Why go backwards?
step 1: figure out why you want to take out the tbi
step 2: realize that that is a dumb reason and accept that tbi is superior to carb
step 3: save yourself a lot of money and pita only to lose performance.
step 4: drink a beer and relax.
wasted wages
1 ton status
IDK......q-jets do a pretty good job offroad.....
and carbs don't have any electrical gremlins and "codes" to deal with out in the middle of nowhere...
and carbs don't have any electrical gremlins and "codes" to deal with out in the middle of nowhere...
OR
step 1: find a guy smarter than you who has a carb now and offer to trade.
IDK......q-jets do a pretty good job offroad.....
and carbs don't have any electrical gremlins and "codes" to deal with out in the middle of nowhere...
If you do very mild wheeling (like just driving around on mountain roads just for fun/camping...stuff like that) than yeah, a q-jet does just fine. But I feel like most people go through a natural progression that as you start wheeling a bit, you realize how fun it is and you want to try harder trails. Once you start down that path, you will find yourself cursing carbs your entire wheeling trip. That was my last outing...hence why I am almost done with a TBI motor swap.
Unless you really want to build a high horsepower motor that you know a TBI unit can't handle, than I truly don't understand why you would want to get rid of the reliability of FI. Especially TBI's which are some of the most simple FI units out there. Just my $0.02
a big thing out here is that i live at an elevation of like 5', an hour and a half from me i could be wheeling at 8k'. i dont feel like rejetting every 5 minute (actually i dont even know enough to try so i wont bother), thats why i want to go efi. yes a quadrajet or a truck avenger do a good job of bridging the gap, but they are still bound by the limitations of their design.
even on the street with out any wheeling, a properly setup efi will always perform better and drive smoother than a carb
even on the street with out any wheeling, a properly setup efi will always perform better and drive smoother than a carb
I actually have helped a couple of friends do just this, on 92 and 94 half ton Chevy's, they both got tired of the computer being outsmarted by rain and little puddles.
And the 92 would just throw random fits of not starting, we never figured out why, now its a 4 barrel Holley, a WORLD of difference.
I'm not sure what all was done, but it for both of them it was in the space of a few hours, from running, to taking it apart, to running again.
Im not sure of what sensors there are and what they do, but I think they just unplugged them after they put the other intake on.
Both of these guys have since taken their trucks through stuff I wouldnt even think of trying with the Blazer, they have also got stuck in said places.
The day before we did the conversion on the 92, we spent the night stuck on a steep, muddy hill after it decided to die on us. Me and a few friends of mine were out with two trucks, the two we converted to carbs.
We couldn't go back the way we came in, so we had to keep going forward, up the steep, rocky, muddy, hill with some deep ditches toward the top, pulling a dead truck. Sure enough We slid in the ditch and took the truck pulling us with us, stuck in mud up to the doorhandles on the passenger side, the driver's side was off the ground.
What a fun day that was.
And the 92 would just throw random fits of not starting, we never figured out why, now its a 4 barrel Holley, a WORLD of difference.
I'm not sure what all was done, but it for both of them it was in the space of a few hours, from running, to taking it apart, to running again.
Im not sure of what sensors there are and what they do, but I think they just unplugged them after they put the other intake on.
Both of these guys have since taken their trucks through stuff I wouldnt even think of trying with the Blazer, they have also got stuck in said places.
The day before we did the conversion on the 92, we spent the night stuck on a steep, muddy hill after it decided to die on us. Me and a few friends of mine were out with two trucks, the two we converted to carbs.
We couldn't go back the way we came in, so we had to keep going forward, up the steep, rocky, muddy, hill with some deep ditches toward the top, pulling a dead truck. Sure enough We slid in the ditch and took the truck pulling us with us, stuck in mud up to the doorhandles on the passenger side, the driver's side was off the ground.
What a fun day that was.
Last edited:
If you do very mild wheeling (like just driving around on mountain roads just for fun/camping...stuff like that) than yeah, a q-jet does just fine. But I feel like most people go through a natural progression that as you start wheeling a bit, you realize how fun it is and you want to try harder trails. Once you start down that path, you will find yourself cursing carbs your entire wheeling trip. That was my last outing...hence why I am almost done with a TBI motor swap.
Unless you really want to build a high horsepower motor that you know a TBI unit can't handle, than I truly don't understand why you would want to get rid of the reliability of FI. Especially TBI's which are some of the most simple FI units out there. Just my $0.02
This post nailed it!
I am soooo much happier with my TBI than I was with the carb.
The reason people get rid of FI is because they never take time to learn how it works. It's a "grass is always greener" mindset. But carbs just bring different issues. It's hard to make a good case that moving away from the stock setup will increase reliability (with a few exceptions, like points ignition, but that's another topic). Instead, you will spend money to bring on new issues, burn more gas and probably hurt off-road performance. It's almost always cheaper and easier to fix what's already there.
As for "codes", these are a feature, not a detriment. When's the last time a carb gave you clues about why the car isn't running right? Just wait until the carb starts giving you problems and then you will really be scratching your head and hardly any shop will be able to help.
As for "codes", these are a feature, not a detriment. When's the last time a carb gave you clues about why the car isn't running right? Just wait until the carb starts giving you problems and then you will really be scratching your head and hardly any shop will be able to help.
ccarley
1/2 ton status
Let me tell you, checking codes anywhere is easy on these trucks too. Both my Chilton's and Hayne's manuals have the instructions on how to pull the codes & see what they mean. All you need is a short piece of wire, a bent nail, or paper clip even.
Even with all the trouble I've had, a swap to carb never crossed my mind. When I had my Jeep Grand Wagoneer, the hot thing to do was to go from carb to TBI. Totally worth it. I like to tell people that it always runs the same. Super dependable/ reliable. I can let my Suburban sit for a month, hit the key, and it fires up like I was driving it yesterday.
Even with all the trouble I've had, a swap to carb never crossed my mind. When I had my Jeep Grand Wagoneer, the hot thing to do was to go from carb to TBI. Totally worth it. I like to tell people that it always runs the same. Super dependable/ reliable. I can let my Suburban sit for a month, hit the key, and it fires up like I was driving it yesterday.
Well said
(rant on) Why does everyone always jump all over someone for wanting to do what they want to do? From his screen name I would think he has a preference for slinging mud. That probably means high horsepower, which I believe isn't very TBI friendly. Now with a custom tune and a lot of trial and error it would probably work, but that isn't his choice.(rant off)
Now to the OP............I'm not sure everything involved, but some of the stuff you will need is; a four barrel intake, carb, non-computer controlled distributor, fuel pressure regulator to drop the fuel pressure to 4-6 psi
Now to the OP............I'm not sure everything involved, but some of the stuff you will need is; a four barrel intake, carb, non-computer controlled distributor, fuel pressure regulator to drop the fuel pressure to 4-6 psi
Bravo Chris.
y5mgisi
1 ton status
I agree with everyone saying TBI is better than a carb on an otherwise TBI motor.
To answer the OP's question, There is very little you NEED to do. What trans do you have?
The basics are just to unbolt the TBI intake and everything attached to it, drop a four barrel intake on, bolt the carb on, drop a normal HEI distributor in, run keyed power to it, and your done with that part.
Then comes fuel. You have two options. Keep your existing electric fuel pump and put in a regulator that will drop it to the 5 or so psi required by the carb. OR, splice into the lines and run a mechanical fuel pump off the motor. THis option wold also require at least a cam swap, if not a whole block swap as most TBI motors didnt have a fuel pump lobe on the cam or the machining done for a fuel pump push rod.
After all that comes the electrical. For the most part you can just keep it all and tie it up out of the way. Or you can just cut everything injection related out of the harnes. OR you can do a good job and spend time with electrcial diagrams and remove all un needed wires properly.
To answer the OP's question, There is very little you NEED to do. What trans do you have?
The basics are just to unbolt the TBI intake and everything attached to it, drop a four barrel intake on, bolt the carb on, drop a normal HEI distributor in, run keyed power to it, and your done with that part.
Then comes fuel. You have two options. Keep your existing electric fuel pump and put in a regulator that will drop it to the 5 or so psi required by the carb. OR, splice into the lines and run a mechanical fuel pump off the motor. THis option wold also require at least a cam swap, if not a whole block swap as most TBI motors didnt have a fuel pump lobe on the cam or the machining done for a fuel pump push rod.
After all that comes the electrical. For the most part you can just keep it all and tie it up out of the way. Or you can just cut everything injection related out of the harnes. OR you can do a good job and spend time with electrcial diagrams and remove all un needed wires properly.
Redneckmudslinger
Registered Member
well i didnt known everyone would actually like the piece of junk tbi system its junk when it comes to power i want power im still young i really could care less about fuel mileage so
ok now can i just stick any 4 barrel 350 manifold on it or do i have to get a certian one just for the tbi motor thanks for help
ok now can i just stick any 4 barrel 350 manifold on it or do i have to get a certian one just for the tbi motor thanks for help
Redneckmudslinger
Registered Member
i forgot to mention i got a 700r4
y5mgisi
1 ton status
Any. BUT, the center two holes on left and right side are angelled steeper. So they will need modified but its easy.
http://persh.org/pickup/TBI%20Intake%20Manifold.htm
http://www.hotrod.com/techarticles/hrdp_1304_late_350_chevy_tbi_heads_on_a_carbureted_1970s_short_block/
http://persh.org/pickup/TBI%20Intake%20Manifold.htm
http://www.hotrod.com/techarticles/hrdp_1304_late_350_chevy_tbi_heads_on_a_carbureted_1970s_short_block/
