Convert 454 Tbi To Carburetor - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1badbowtie · 05-23-2006, 01:22 AM

Has anyone converted a 454 TBI to Carburetor setup?? If so, any ideas or suggestions for me.

THANKS,

ANDY

87 STEPPER · 05-23-2006, 07:08 AM

I haven't but i don't know why you would want to do that.

If this truck is gonna be a daily driver id'e leave it alone.

If your gonna race it then rip it outta there.

With that said,

The TBI system isn't the best system out there but it beats any carb you can slap on there.

If your reason or thinking you will get better fuel mileage with a carb you wont it's a 454 they like fuel and lots of it.

If your dead set on this swap over heres what i can think of off the top of my head that you will need or have to do.

An intake and carb, new is best if you can swing it and gasket set.

A new or another air filter to fit the carb.

A mechanical engine fuel pump or an electric pump to support the carb. 15PSI! and associated plumbing carb to pump, pump to tank.

You will have to deactivate the in tank fuel pump for the TBI removing it is best but not necessary and removing the TBI plumbing at the rear of the eng.

You will probably need to get a new TV & Throttle Cable's but im not 100% on that it just depends on how far fwd the cables have to go to hook up on the carb.

You will need to unhook all the electrical connectors for all the TBI sensors and stow out of the way. I.E. The Injectors, IAC, TPS, CTS, MAP, O2, and so on you will have to locate and disconnect the EST so the ECM won't try to adjust the timing once the other sensors are taken out of the loop and you will probably have to reset the base timing since the ECM won't be making the cailbrated adjustment's any longer you may need to install a vaccum adv. distributor.

I can't think of any thing else and im sure there is but that should get you started.

Like i said before id'e leave it alone TBI is a good FI system and your not gonna improve that much with a carb.

Good luck

1badbowtie · 05-23-2006, 04:09 PM

Well my main objective is the engine light is always coming on and then it Falls on its face as far as acceleration goes. I checked the code and it was 44 for Lean Exhause condition. I just replaced the Distributor and timing set, because they were both wore out. I adjusted the timing to 6 degrees advanced. I hoped replacing these 2 would solve my problem, but it didn't. I don't think it's the fuel pump cause I stilll go through a ton of gas, so maybe I just need a new O2 sensor, or possibly the Converter is plugged, because I only have this problem when I try and step on it and go fast, but if I baby it and accelerate slow, no engine light, and it runs fine. Any ideas??

MylilBowTie · 05-23-2006, 05:09 PM

Fuel filter?

87 STEPPER · 05-24-2006, 05:24 AM

The O2 sensor sounds like a good place to start and the cat could be partially melted internally and causing that if neither one have ever been replaced and the truck has alot of miles on it then it's probably time to put new ones on it.

Probably not a bad idea to replace the plugs too if you haven't allready.

If you replace the cat id'e go with any good brand name high flow version!

05-23-2006, 01:22 AM	#1
1badbowtie Registered User Join Date: Mar 2006 Location: Southern Oregon Posts: 23	Convert 454 Tbi To Carburetor Has anyone converted a 454 TBI to Carburetor setup?? If so, any ideas or suggestions for me. THANKS, ANDY

05-23-2006, 07:08 AM	#2
87 STEPPER STILL PLAYS WITH TRUX Join Date: Nov 2002 Location: Melbourne, Fla. Posts: 2,764	Re: Convert 454 Tbi To Carburetor I haven't but i don't know why you would want to do that. If this truck is gonna be a daily driver id'e leave it alone. If your gonna race it then rip it outta there. With that said, The TBI system isn't the best system out there but it beats any carb you can slap on there. If your reason or thinking you will get better fuel mileage with a carb you wont it's a 454 they like fuel and lots of it. If your dead set on this swap over heres what i can think of off the top of my head that you will need or have to do. An intake and carb, new is best if you can swing it and gasket set. A new or another air filter to fit the carb. A mechanical engine fuel pump or an electric pump to support the carb. 15PSI! and associated plumbing carb to pump, pump to tank. You will have to deactivate the in tank fuel pump for the TBI removing it is best but not necessary and removing the TBI plumbing at the rear of the eng. You will probably need to get a new TV & Throttle Cable's but im not 100% on that it just depends on how far fwd the cables have to go to hook up on the carb. You will need to unhook all the electrical connectors for all the TBI sensors and stow out of the way. I.E. The Injectors, IAC, TPS, CTS, MAP, O2, and so on you will have to locate and disconnect the EST so the ECM won't try to adjust the timing once the other sensors are taken out of the loop and you will probably have to reset the base timing since the ECM won't be making the cailbrated adjustment's any longer you may need to install a vaccum adv. distributor. I can't think of any thing else and im sure there is but that should get you started. Like i said before id'e leave it alone TBI is a good FI system and your not gonna improve that much with a carb. Good luck __________________ ~~Bruce~~ MY 87 STEPPER MY 99 2D/WD TAHOE

05-23-2006, 04:09 PM	#3
1badbowtie Registered User Join Date: Mar 2006 Location: Southern Oregon Posts: 23	Re: Convert 454 Tbi To Carburetor Well my main objective is the engine light is always coming on and then it Falls on its face as far as acceleration goes. I checked the code and it was 44 for Lean Exhause condition. I just replaced the Distributor and timing set, because they were both wore out. I adjusted the timing to 6 degrees advanced. I hoped replacing these 2 would solve my problem, but it didn't. I don't think it's the fuel pump cause I stilll go through a ton of gas, so maybe I just need a new O2 sensor, or possibly the Converter is plugged, because I only have this problem when I try and step on it and go fast, but if I baby it and accelerate slow, no engine light, and it runs fine. Any ideas??

05-23-2006, 05:09 PM	#4
MylilBowTie Right turn Clyde Join Date: Nov 2002 Location: Cincinnati, Ohio Posts: 2,911	Re: Convert 454 Tbi To Carburetor Fuel filter? __________________ 1974 C25 LWB: 454 4bbl Carb / TH400 / 3.73 1992 Camaro RS 305 TBI

05-24-2006, 05:24 AM	#5
87 STEPPER STILL PLAYS WITH TRUX Join Date: Nov 2002 Location: Melbourne, Fla. Posts: 2,764	Re: Convert 454 Tbi To Carburetor The O2 sensor sounds like a good place to start and the cat could be partially melted internally and causing that if neither one have ever been replaced and the truck has alot of miles on it then it's probably time to put new ones on it. Probably not a bad idea to replace the plugs too if you haven't allready. If you replace the cat id'e go with any good brand name high flow version! __________________ ~~Bruce~~ MY 87 STEPPER MY 99 2D/WD TAHOE



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