Switching from FI to CARB

[blackk5350]

i need more power out of my truck and its going to be my toy soon after i get another car so i dont mind the gas prices. I would like to know what needs to come out, engine,computer wires ect. to run a new carb engine. So what im asking is what dont i need when i put the new carb engine in their? i dont want wires and everything hanging everywhere i just want a clean engine bay and the power of the carbed engines. Also any recomendations on small blocks? really want a 383 or a 400 sb. thanks alot

 

[dyeager535]

Your a member, I'd *seriously* consider finding someone on here local that wants TBI, to work with you on pulling it. There is money to be had!

To get the wires out, you'll need to pull just about all of them engine related, except the starter and alternator wiring.

 

[Wasatch K5]

I think you're making a mistake.

The '87 and '88 Blazers are to me the "Best of Breed". The TBI engine is superior to the carbureted engines in terms of power and economy. Personally I think the '85 - '88 styling is the best, and they have the improvements to the 700R4 (though I'm not sure if that's true for the '87's).

If you want more power, I think I would go the route of improving the TBI engine. A cam change and a new chip will help. If it has not been thoroughly rebuilt, that will help, too.

I don't know what kind of transmission you have. If you have a 700R4 the lock up is controlled by the ecm with some engine sensors. You'll have to change the torque converter lock up which isn't difficult or expensive, it's just one more thing to do.

I would stop and really think this through before you go back to a carbureted engine.

 

[lak2004]

Check out www.tbichips.com and look into the TBI mods he has listed. Good info there for gaining power for a lot cheaper than you can likely get an engine and you get to keep the advantages of FI

 

[chevyuser74]

I Agree Ditching The Injection Would Be A Mistake If U Want A Bigger Engine Keep The Tbi And Have It Programmed To Your Engine. plus you if u ditch it u will have to buy something to control the 700r4 lockup

 

[slyguy_22]

X3! But if you insist on removing your tbi find a local guy who wants it and just swap harnesses! will make life alot eaiser. Btw i have a 406 with my tbi on it. I dare you to build a carbed 383 or 400 that can keep up. also those truck avenger carbs suck!

 

[Chaddy]

I think you're making a mistake.

.

 

[blackk5350]

ok i guess you all changed my mind. but when you switch to a bigger engine as slyguy did (406ci) wouldnt you need bigger injectors, throttle body, and fuel pump,pressure? slyguy pm me and tell me what you did to get the 406 to run right in oyur truck. thanks alot guysfor steering me in the right direction. the next thing on my list then is straight pipes headers, cam and chip? sound Good?

 

[dyeager535]

I'm not going to get into an argument here, I'm just going to state facts. Every engine has different timing and fueling requirements. This is governed by the ENTIRE drivetrain, which is why every single drivetrain variation GM made had a different chip (as small a change as AC or not), and is why the 454 and 350 don't use the same injectors.

While you may get away with having improperly sized injectors or chip tuned, the chance of running lean is extremely great, and will not show until typically you hole a piston.

This is GM TBI 101: At throttle positions other than idle/cruise, the system has no way of compensating fuel delivery. Fuel delivery is governed by pre-programmed values in the chip in this case (and I'm talking about starting from a stop even) so if the engine is running lean, you won't know. Why is it this way? Because a narrowband O2 sensor is only accurate at 14.7:1 AFR, which is NOT optimum for power out of a gasoline engine, therefore under acceleration, it's input is worthless, and GM engineers knew this. There is no arguing this fact, it has been SHOWN on this board before. If you get *far enough* outside the parameters of the original engine, there is no one here that can say for certain if your engine will be safe or not.

Injection can make more power than a carb, so I'm not trying to get you away from it. But it takes a smart approach to EFI to make SAFE power.

 

[Thunder]

You can buy crate TBI 383s. Some even come with a chip burned for the engines specs.
http://www.blueprintengines.com/popular_configurations/index.html?topic=options&pcsci=5
These are a couple of nice engines. Altho the price seems a little high. Its not bad concidering all the goodys you get, Including the a chip & performance heads.

 

[k20]

I ripped my FI out and put on a carb. I got dog tired of problems. Go outside, wont start, its always a 40-80 dollar sensor.....gets old quick. With the carb its a heckuva lot easier to diagnose a no start condition.

Took me about 3 days to do the swap. I kept my intank fuel pumps and then put a bypass regulator on it to drop the 14psi from the tbi pumps to 6psi for the carb and I keep the benefits of a return system vs a non-return system.

I like the carb, and I get about the same mileage as I did with my fuel injection and power was about the same. After the swap I put in an even bigger cam that the fuel injection couldnt support, so I ended up gaining that way.