Chevy TBI To Carb Conversion: 8 Most Important Parts

‍What parts do I need?

Intake manifold

An intake manifold on a throttle body injection powered vehicle distributes plenty of fresh air from the outside straight to the vehicle engine's cylinders. They serve a bit of a different purpose when paired up with a carburetor fueled vehicle, and instead send that air from the outside to the carburetor for fixing.

There may be differences between the intake manifold on a TBI powered vehicle and a carb powered. The connections are likely different when sending air to cylinders vs sending to a carb. It is possible to find an adapter for the purpose that sends out out on a different path.

Distributor

You'll need a different distributor when switching to carburetor – in part because your existing distributor runs by a computer, and removing the TBI takes that computer out. You'll want an HEI distributor – which stands for High Energy Ignition. HEI allows for a more powerful spark, and makes better use of wider spark plug gaps. The result is more complete, more powerful combustion than with TBI – and better for modified performance engines.

Adjustable Fuel Regulator

The throttle body system sends fuel at a higher pressure than a carburetor needs, so the two aren't exactly compatible. You'll want to add a adjustable fuel pressure regulator to the fuel line.

Fuel Pump

Instead of putting in a adjustable fuel regulator, you do have the option of installing a fuel pump. A fuel pump is more simple than a regulator, and there is a chance that your existing fuel pump is aged anyway.

Transmission

Your current transmission with a TBI uses sensors that tell the vehicle when to shift. You do have a couple of options though: You could get a transmission controller computer online or from a dealership or install a different transmission that doesn't use electronics. It's possible that you'll also need a throttle kick down cable for the purpose with a non electronic transmission.

Air cleaner or filter

While not every installation needs it, you might also require an air cleaner or filter. Like a vacuum, your intake manifold is sending high pressure air into the carb and could use something to keep debris from getting clogged in ther.

A carburetor

This is probably the most obvious, so we saved it for last. You'll need a carbureator with appropriate hoses. We suggest doing some research in regards to which one will give you the durability and setup you want – though in truth they aren't all that different. Other factors like the abilities of the intake manifold have an impact too.

Why switch from TBI to carburetor?

There are a few reasons to switch to carburetor. Some people who modify old Chevrolets and Fords find that TBI messed with modified engines and results in error codes and performance issues, in part because TBI is computer controlled and not exactly setup for a more powerful engine that takes fuel differently.

Others also like the sound made with a carburetor – maybe out of nostalgia. Every seen a parade of vehicles leave a car show – or better yet heard older cars leave a car show? You are hearing the sound of older fuel systems at work – and let's be honest, they sound pretty cool compared to today's rather quiet vehicle.

Carburetors are otherwise considered original equipment on older cars. As someone who has been to a few car shows, many attendees find original cars invaluable. Original cars from before the 1980s certainly do have a unique sound, smell, and look to them, and their preservation is definitely something we stand by!

Are there any disadvantages to a carburetor?

Yes, in their own way. Carburetors can get gummed up by fuel and require cleaning, which is practically non existent with fuel injector systems. Cold weather can also cause issues with carburetors and require a bit of warm up time. Drivers who haven't operated a carb driven vehicle might also get confused about why it responds differently than a injection powered vehicle and could have a hard time starting it.

In reality, carburetors were ushered away by newer technology – and the Environmental Protection Agency. Carburetors, while capable of delivering powerful performance, are not computer controlled and are incapable of effectively operating at peak efficiency constantly. A fuel injector powered vehicle has a computer capable of delivering different amounts of fuel at different times, including while idling, which a carburetor is a consistent – sometimes unnecessary fuel flow.

Are carburetors illegal to use?

In a word, no. Carburetors are more heavily regulated than they used to be. Attempts to make carburetors more efficient made them significantly worse and harder to run. In many ways, fuel injection replaced carburetors not because carburetors are “illegal” but because fuel injection systems are easier to maintain and better for gas and the environment overall.

California is a bit more strict about this. They restrict the advertising, selling, and using of performance parts for road worthy vehicles unless those parts comply with the CARB Executive Order. The same executive order also gradually restricts the use of carburetors in smaller engines like lawnmowers, snowblowers and weed whackers.

Look at your state laws regarding what kind of setup you aren't allowed to have in your vehicle. The idea of being pulled over by the police because your setup is not legal sounds unpleasant – and you might have to undo the hard work and time you put into your vehicle.

Can I do this myself or will I need help?

If you know your cars well, it's always possible. One option that we've read about is to go to a performance car shop and ask that they setup the specifications within your carburetor parts to mimic the specs of the original – or use a template that makes the most sense. Some performance car shops have done enough of these to put together a system that effectively works to provide the performance you want out of your carburetor without having to dig into the science yourself.

Where should I buy all of these parts?

It's pretty easy to buy auto parts online. We suggest finding a place that can match or exceed your expertise. Replacing a TBI system with a carburetor isn't easy, and you'll want a store or retailer that can answer any specific questions you might have about your vehicle. While these places could cost a little more, their experience will be invaluable. Look up the best performance parts store and you'll find one online or in person that fits your needs.