Tbi vs carb

[Jawzjeep]

I see a lot of great opinions and thoughts in this thread I'd love to quote and add my two cents to, but there's just to many to quote them all. So I'll go at it like this. I completely agree that it is a better idea to keep what you have vs swapping one way or another, there aren't enough good benefits to make a swap like that worth while.

That being said I've worked on a ton of carb'ed GM engines, and TBI, more so back in the day. The biggest issue we saw with TBI was lack of understanding them and I think that to some degree still holds true. In a carb'ed vehicle for people use to carburetors it is generally easy to understand what problem causes what symptom, with modern fuel injection the slightest thing out of parameter and the system sets a code. But with TBI the computer systems were not so sensitive, so you could have a rig run like crap with no check engine light and the mechanic not knowing what direction to go in, but in reality the TBI system is very simple and reliable. To me the biggest benefit in the TBI system is consistency and less maintenance, which might not matter for all but in a daily not having to tweak the carb, or change the plugs as often is a benefit.

I'm rockin' an 84 C20 with 305 edelbrock the former owner put on. It runs right and good. Would I rather have a Q-jet yes I would, but will I remove a perfectly good carb to do it. No. And although I would prefer TBI to my carb, I'll never convert, not enough benefits given the work involved to do it right.

I would encourage the OP to consider selling his truck to someone that would like TBI and buying one that is carbed already. If you insist on the conversion please do it the right way. Get a carbed parts truck and put make it as close to factory conversion as you can unless you plan for a custom fuel system. Please do not be the guy that tries to regulate down the TBI pump pressure for the carburetor and don't use some sort of adaptor to adapt a 4 barrel carb to the TBI manifold. That will only lead to heart ache and pain.

I appreciate the opinion. I was asking which way people go if they swap. Im happy with the way my rig is and never was considering selling it. And im a cheap sob. If I was to swap from tbi to carb getting a parts rig is after all the smartest route. I'll resell most of it and make it just about free.

Much like you stated, im not looking to change for the sake of change. It works fine so I'll leave it. Im a firm believer in the phase, "what's worse, the devil you do know or the devil you dont?"

I do however have a 454 that I'll be swapping in later. This info I collect will help me make a choice on how I go with the big block. The 454 is stock and tbi already so unless I hear a fantastic reason to go Carbed its staying tbi. About as plug and play as I can get.

 

[SirRobyn0]

I appreciate the opinion. I was asking which way people go if they swap. Im happy with the way my rig is and never was considering selling it. And im a cheap sob. If I was to swap from tbi to carb getting a parts rig is after all the smartest route. I'll resell most of it and make it just about free.

Much like you stated, im not looking to change for the sake of change. It works fine so I'll leave it. Im a firm believer in the phase, "what's worse, the devil you do know or the devil you dont?"

I do however have a 454 that I'll be swapping in later. This info I collect will help me make a choice on how I go with the big block. The 454 is stock and tbi already so unless I hear a fantastic reason to go Carbed its staying tbi. About as plug and play as I can get.

I may have jumped the gun a little bit in my comments. The thing is at the shop I've seen engines switched in both directions. It seems like they are either done so well that you can't tell, or it's a half ass job, and comes in because it doesn't and has never run right at the owner can't figure out why. For that reason I probably have a somewhat skewed view of those sort of swaps. I'm a cheap SOB to so understand that one!

 

[Jawzjeep]

I may have jumped the gun a little bit in my comments. The thing is at the shop I've seen engines switched in both directions. It seems like they are either done so well that you can't tell, or it's a half ass job, and comes in because it doesn't and has never run right at the owner can't figure out why. For that reason I probably have a somewhat skewed view of those sort of swaps. I'm a cheap SOB to so understand that one!

Totally understand you on that. Im a painter and my 'do the job' price is significantly cheaper than my 'fix the job' price. I'd rather not deal with someone else's attempt.

Im asking for it too so dont be shy telling me how it is. First hand experience is always the best.

 

[harrismje]

Without starting a fuss, I know opinions vary.

Is there I consensus here on this? Are more people swapping from tbi to carb or carb to tbi (or another form of injection)? Say on a basic stock engine with a 4 barrel already or stock tbi.
Does this opinion differ between a big or small block?

Asking for a friend...

If this is covered then point me in the right direction. Thanks.

If you have a carb and won't fuel injection remember for standard sbc the tuned port injection is easy wiring is basically ground,hot wire,ignition wire electric fuel pump holley blue works good

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[louu]

I'm in the planning stages of installing an aftermarket(based on the gm system)tbi setup.it will be a few weeks before the actual install.

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Are you talking about the performance fuel injection one? I just put that on my truck https://www.gmsquarebody.com/thread...ch-of-other-upgrades.32572/page-2#post-667520
It's iight, better than a carb for sure

 

[WebMonkey]

i love the fuel injection in my hemi truck and my polaris 4 wheeler.

i have the 85 k20 for the 'older school'.
the quadrajet has no fear of being replaced.

 

[dusterdude]

Are you talking about the performance fuel injection one? I just put that on my truck https://www.gmsquarebody.com/thread...ch-of-other-upgrades.32572/page-2#post-667520
It's iight, better than a carb for sure

Yes,that's it.I'm going to read your thread right now.

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[louu]

Yes,that's it.I'm going to read your thread right now.

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If you have any questions let me know, just post in the thread. I'm pretty happy with it for as cheap as it was compared to all the other systems out there. The only problem I had so far was it would throw a 42 code once and a while but still ran just as good with it. That code means change the ignition module. I changed it and the code stopped. My engine has a pretty big cam in it so at idle it still has a gasoline smell out the exhaust a tiny bit but the with the carb there was pretty much raw gasoline coming out the exhaust. Overall like I said it's wayyy better than a carb and it's hard to beat for the price

 

[dusterdude]

Groovy,ill keep you in mind.thanks

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[AuroraGirl]

My cousin had a firebird that would have been factory TBI but it was so butchered.. that I told him since it was still a regular SBC.. just put a carb on.. i helped him because the mess of wiring and hatchet job repairs(THEY USED DRYWALL SCREWS TO HOLD THE BATTERY CABLE ON THE BATTERY)
we figured trying to fix that wiring and systems was useless because the fact its not 100% self aware, it isnt exactly performance oriented, and the original wiring and components are setup year-to-year, model-to-model, emissions-to-emissions and trying to piece the proper electronics and wiring was just not realistic. a 400 dollar trip to oreillies fixed that. he had a 700r4 so i think he needed a bracket off the internet but otherwise worked okay, i cant remember if the fuel supply had to be messed with, as i believe tbi is low pressure electric?? Idk, but he got rid of that POS shortly later anyway

 

[Raider L]

I just prefer to not have a computer doing anything and for the reason of getting stuck in the woods. The way I have my carb and ignition system set up now I can do carb and distributor tune-ups, or overhauls on the side of the road, in the woods, wherever.
That's one reason why I have a Holley on my motor and that is the simplicity of that carburetor, and the ease of tuning and rebuilding. The last two times I over hauled my Holley I did it sitting out on the curb in front of the truck. I had a pan to put the parts in, a spray can of carb cleaner, and some clean red rags, the Holley rebuild box of pieces parts. And did it sitting out there under a big oak tree shade, where I park my truck, it was a nice day, I had my radio out there to listen to, my coffee and a stool to sit on, it was a most pleasant experience.

 

[K5ride]

Many customers have told me they prefer the TBI for off road and dirty environments. On a V8, each injector feeds 4 cylinders and has a much larger orifice than the multi-port. They are supposed to not clog as easily. I'm not sure if it's true or not. It would make sense, but you would think if you have a good fuel filter it would catch any debris. Maybe they are talking about fuel deposits?? I've never owned one, but my son has one on his 1991 work truck he uses for construction work. He's had it for decades and has never had any issues with the TBI. I'm still running a carb on my 75 and that works good too.

 

[Jawzjeep]

Raider L

This is my first time really building a rig with fuel injection that'll be taken out in the woods or mountains. All my other vehicles are carbureted for the exact reasons you mentioned. And I really haven't had any problems with them except for in my Jeep when I start flopping it sideways.

 

[Jawzjeep]

I'm definitely keeping the Tbi set up thats on there now, it's working fine and I see no reason to change it for the sake of change.

For my future 454/5 speed swap I was planning on throwing some cash into the engine, tossing the tbi, and building for some power. But, I may have to reconsider and just go a basic rebuild and stick with the tbi. It kind of depends on what the economy ends up doing. Things aren't getting any cheaper real quick.

Thanks for everyone's feedback

 

[eric 87]

I see a lot of great opinions and thoughts in this thread I'd love to quote and add my two cents to, but there's just to many to quote them all. So I'll go at it like this. I completely agree that it is a better idea to keep what you have vs swapping one way or another, there aren't enough good benefits to make a swap like that worth while.

That being said I've worked on a ton of carb'ed GM engines, and TBI, more so back in the day. The biggest issue we saw with TBI was lack of understanding them and I think that to some degree still holds true. In a carb'ed vehicle for people use to carburetors it is generally easy to understand what problem causes what symptom, with modern fuel injection the slightest thing out of parameter and the system sets a code. But with TBI the computer systems were not so sensitive, so you could have a rig run like crap with no check engine light and the mechanic not knowing what direction to go in, but in reality the TBI system is very simple and reliable. To me the biggest benefit in the TBI system is consistency and less maintenance, which might not matter for all but in a daily not having to tweak the carb, or change the plugs as often is a benefit.

I'm rockin' an 84 C20 with 305 edelbrock the former owner put on. It runs right and good. Would I rather have a Q-jet yes I would, but will I remove a perfectly good carb to do it. No. And although I would prefer TBI to my carb, I'll never convert, not enough benefits given the work involved to do it right.

I would encourage the OP to consider selling his truck to someone that would like TBI and buying one that is carbed already. If you insist on the conversion please do it the right way. Get a carbed parts truck and put make it as close to factory conversion as you can unless you plan for a custom fuel system. Please do not be the guy that tries to regulate down the TBI pump pressure for the carburetor and don't use some sort of adaptor to adapt a 4 barrel carb to the TBI manifold. That will only lead to heart ache and pain.

Well that is at least a sensible offering of opinion. I am doing this swap probably in the next couple weeks. I have an 87 305 TBI. I am chasing the tail. I have had the throttle body rebuilt last week by a guy the knows them and loves them. I have replaced the computer. TPS MAP IAC AND TEMP Sensor...oh and O2 sensor as well. Even the new parts were checked with volt ohm and or vacuum as needed . The signal wires and voltage on them tested. Well lo and behold the thing that was causing the lady finger firecracker popping on accel was the pick up coil. Oh the fuel reg was rebuilt when doing the Throttle body.
NOW I have this idle issue up and down. REAL low and shutting down sometimes at stops. Then on restart it goes to about 1800-2200 rpm and unlike a carb there is no kicking down a choke. But that is how high it is idling at times.
Now I have this shutting down issue as I am driving down the road. Lose all power. I coast to stop and it will crank...but I have to do the no no and pump gas a couple times for it to start which I know you shouldn't do. Pressure has been tested etc.
Oh and did I say I replace the computer? OH I did.

So to ditch the computer I and all the sensors etc I am ditching TBI. Also the pass tank primes but the minute I flip the switch it kills the engine so that will be address on the swap. I intend on pulling pumps from both and using an electric pump for the carb. I don't like moving the tanks to the single bed since then wife would have to flip the cover back on bad weather days. Frankly not my idea of fun either. Slush all over the clothes!
I am swapping distributor and intake as well. Was looking for a good parts list from others. It is a stock 305 and it actually is running strong when it isn't trying to leave me on the side of the road. When it shut down it took the stereo out as well for a minute or two. I think this might be electrical but the idle issue going real low and real high....
This swap is more of a lets get back to basics sort of dependability. Wife now will not drive it and loves the truck. I don't blame her. Last night I was getting ready to list it as is on Facebook. It is solid shortbed.