91 Chev 4x4 Dually TBI 350 and 4L80E considering TBI to carb swap

[GrahamV]

I have a 1991 Chev 1 ton Dually 4x4. I have done a total frame up restoration on it and have swapped in a 1971 4 bolt main 350 with flat top pistons, bored 30 over, bigger valves, headers, cam, distributor, edelbrock TBI intake, and all sorts of other fancy stuff. The motor has never run properly in there, and burns a sick amount of gas, and I was told to expect that by lots of mechanics and friends. I have been told that you can buy chips that will smarten this up and have also been told by some old school mechanis to do away with the TBI and put a carb on it. I have all the parts to do this but am not sure which is a smarter option. The motor is a slug trying to pull a trailer on the TBI and I have been told by the folks who machined it and built the motor that if it was runnin right it would pull like a *******. The other question would be if I swapped a carb onto it with the 4L80E transmission I am certain I would have to do something to make that transmission work right? I have talked to another mechanic friend and he said a PROM chip would be what I need. I am not wild about the TBI and always seem to be spendin money on somethin that doesn't make it run any better. I have also been told that because the truck is a 1 ton it didn't have as much emmision control on it and would be easier to make performance parts work. Whether there is any truth to that I hve no idea. Everyone has their own opinion so a few more wouldn't hurt. Especially if someone has done this before. I have good mechanical knowledge but this is my first go with the 88 and up body style trucks so fuel injection has never been a problem for me.

[Sneakysportsman]

Take it from expierience, any time or thing that is change on a TBI engine that effects flow of air and fuel the computer will not compensate for the changes. Yes, the computer can be taught to do exactly what you want it to. Depending on your specific parts 1 in 9999999999 million chances that you will get a custom mail order chip that will actually work. You can hire someone to sit in the Passenger side with a laptop and program it as you go down the road, and when finished that person can burn a chip to store the parameters. The truck is still basic enough to put a carb in it and every thing function well. You will have to clip a few unneeded wires and take out the Check engine light but all gauges will function properly. You can get a efi to carb fuel regulator made specifically to keep the pump in the tank and function properly. Go to Professional Products, Inc. - Guided by Technology. Driven by Knowledge. Excellence Through Innovation. Professional Video, Audio, Data & Control Solutions. and look for it. If you want fuel milage remember this bigger is not always better, I am talking about the carb, a 600cfm carb is more than adequate for and engine of your size and application. I have just converted back to TBI from a Carb for better fuel milage. YouTube - Broadcast Yourself. 95 chevy truck burnout is a small clip of my results. my current application is a 350 bored 60 over, flat top pistons and 906 vortec heads with 2.02in and 1.60 ex valves. I have double drilled vortec heads that allow me to use the original TBI intake. I get right at 25mpg from the engine but it has very little performance addition from the heads until you get up into the upper range of the RPM level. All this info is from total expierience. I have other post in here outlining gimmik TBI power bolt ons.

[don johnson]

Originally Posted by Sneakysportsman

Take it from expierience, any time or thing that is change on a TBI engine that effects flow of air and fuel the computer will not compensate for the changes. Yes, the computer can be taught to do exactly what you want it to. Depending on your specific parts 1 in 9999999999 million chances that you will get a custom mail order chip that will actually work. You can hire someone to sit in the Passenger side with a laptop and program it as you go down the road, and when finished that person can burn a chip to store the parameters. The truck is still basic enough to put a carb in it and every thing function well. You will have to clip a few unneeded wires and take out the Check engine light but all gauges will function properly. You can get a efi to carb fuel regulator made specifically to keep the pump in the tank and function properly. Go to Professional Products, Inc. - Guided by Technology. Driven by Knowledge. Excellence Through Innovation. Professional Video, Audio, Data & Control Solutions. and look for it. If you want fuel milage remember this bigger is not always better, I am talking about the carb, a 600cfm carb is more than adequate for and engine of your size and application. I have just converted back to TBI from a Carb for better fuel milage. YouTube - Broadcast Yourself. 95 chevy truck burnout is a small clip of my results. my current application is a 350 bored 60 over, flat top pistons and 906 vortec heads with 2.02in and 1.60 ex valves. I have double drilled vortec heads that allow me to use the original TBI intake. I get right at 25mpg from the engine but it has very little performance addition from the heads until you get up into the upper range of the RPM level. All this info is from total expierience. I have other post in here outlining gimmik TBI power bolt ons.

Sneaky, I also have a post here and want to trash the TBI on my 1995 454 and convert to carburator for many reasons. However I do not want to buy the $1,000 TCI or GM stand alone computer to manage the transmission. Can you walk us through the steps that are required to remove the TBI yet retain the factory computer to manage the transmission.

Thanks!