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LS1 Carb Swap - Tech

Replacing The Stock EFI System With A Four-Barrel Carb On A Gen III Chevy Engine
From the October, 2009 issue of Street Rodder
By Ryan Manson
Ls1 Carb Swap Carburetor
Ls1 Carb Swap Stock
Here's our LS1 engine in its... 
   
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Ls1 Carb Swap Stock
Here's our LS1 engine in its relatively stock guise. Note the coil packs, fuel rails and injectors and the molded nylon intake manifold. Not the prettiest small block that Chevy made.
Ls1 Carb Swap Edelbrock
At first glance, you'll notice... 
   
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Ls1 Carb Swap Edelbrock
At first glance, you'll notice how similar Edelbrock's Gen III carburetor kit looks compared to standard four barrel intake/carb setups of the early Gen I variety. The dual-plane Performer RPM intake and carb combo provide a broad torque curve from 1,500-6,500 rpm. Since the Gen III engines don't feature a boss for a mechanical fuel pump, a 6.5psi, 120gph electric unit will provide the fuel to the engine.
Ls1 Carb Swap Intake Gasket
Individual port O-ring seals... 
   
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Ls1 Carb Swap Intake Gasket
Individual port O-ring seals are one major improvement over the classic Gen I and II intake gaskets. Note the port design unique to the Gen III series of engines.
Ls1 Carb Swap Intake Manifold
With the carbureted intake... 
   
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Ls1 Carb Swap Intake Manifold
With the carbureted intake manifold on the engine, it's easy to overlook the valve covers and headers and mistake the engine as a Gen II.
Ls1 Carb Swap Timing Control Module
The MSD 6LS Timing Control... 
   
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Ls1 Carb Swap Timing Control Module
The MSD 6LS Timing Control Module replaces the stock EFI hardware and allows the user to map a timing advance curve using Pro-Data+ software and fits with matching factory connections for a direct fit installation. Other features include a two-step rev limiter, a vacuum advance curve for cruising economy, and a step retard for use with Nitrous.
Ls1 Carb Swap Throttle Position Sensor
When the stock EFI components... 
   
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Ls1 Carb Swap Throttle Position Sensor
When the stock EFI components were removed, with it went a couple of items that we need to replace. One of those is the TPS, or throttle position sensor. The original unit attached to the throttle body and sent the throttle position information to the engine ECU as well as to the 4L60E transmission's TCI electronic control unit. For our carbureted system, we'll be using this TCI remote TPS that will give the TCI trans control unit the information that it needs to control the electronic transmission.
Ls1 Carb Swap Edelbrock Intake
The Edelbrock intake attaches... 
   
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Ls1 Carb Swap Edelbrock Intake
The Edelbrock intake attaches to the heads using ten 6mm x 50mm hex bolts. Intake bolts are torqued in a rotational sequence starting at the center to 11 lb-ft.
Ls1 Carb Swap Hose Fitting
An 1/8-inch NPT to 1/4-inch... 
   
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Ls1 Carb Swap Hose Fitting
An 1/8-inch NPT to 1/4-inch hose fitting installs below the carb base. This will attach to the manifold absolute pressure sensor or MAP sensor after the carb is installed.
Ls1 Carb Swap Edelbrock Thunder Series
Handling the fuel delivery... 
   
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Ls1 Carb Swap Edelbrock Thunder Series
Handling the fuel delivery duties is an Edelbrock Thunder Series 650cfm (#1806) carb.
Ls1 Carb Swap Edelbrock Intake Manifold
The Edelbrock intake manifold... 
   
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Ls1 Carb Swap Edelbrock Intake Manifold
The Edelbrock intake manifold has provisions for the LS1 timing control module to bolt directly to it, easing installation. The timing control module's harness is designed as a plug-and-play unit with corresponding connectors for the crankshaft position sensor and the MAP sensor. This is one of the other items that went with the original EFI components that needs to be replaced. This attaches to the rear carb stub and a 1/4-inch hose connects the sensor to the fitting below the carb.

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