EVIL ENERGY LS1 LS2 LS6 Cathedral Port Single Plane Intake Manifold & 650 CFM Carburetor Kit

LS1 LS2 LS6 Single Plane Intake Manifold & 650 CFM Carburetor Kit

Converting a compatible LS engine from EFI to a carbureted setup requires the intake manifold, carburetor, ignition control, fuel delivery, and mechanical interfaces to work together. This EVIL ENERGY LS carburetor intake kit combines a single plane manifold for compatible LS1, LS2, and LS6-style cathedral-port engines with a 650 CFM carburetor for performance-oriented LS combinations where higher-RPM airflow and adjustable secondary response are priorities.

The 650 CFM configuration provides a more moderate airflow option than stepping directly into a larger carburetor, but carburetor size still needs to match the complete engine combination. The single plane manifold is designed around higher engine speeds, so displacement, camshaft, cylinder heads, exhaust, gearing, ignition control, and intended RPM range should all be considered before ordering.

Fitment first: This intake is designed for compatible cathedral-port LS configurations. It is not intended for LS3, L92, L99, L76, or other rectangular-port cylinder heads unless compatible cathedral-port heads have been installed.

Is This Kit Right for Your LS Build?

Is a 650 CFM Carburetor Right for Your LS?

A 650 CFM carburetor should be selected from the airflow demand of the complete engine rather than displacement alone. Maximum RPM, volumetric efficiency, camshaft profile, cylinder-head airflow, compression ratio, exhaust, gearing, and intended use all influence the required carburetor size.

This combination can provide a useful middle ground for compatible performance LS builds that need more airflow than a mild street setup without automatically moving to a larger 750 or 850 CFM carburetor. However, an aggressively modified engine operating near the upper end of the manifold's intended range may require additional airflow.

The included performance carburetor uses an adjustable air valve secondary system. Secondary airflow increases with engine demand, while adjustment allows the secondary response to be better matched to the engine and vehicle combination instead of relying on one fixed response for every setup.

Why Use a Single Plane Intake with a 650 CFM Carburetor?

A single plane intake uses a common plenum feeding the intake runners and generally shifts the intake system toward higher-RPM airflow rather than maximizing low-speed response. This makes the manifold better suited to appropriately configured performance street, street/strip, track, hot rod, and carbureted LS swap combinations.

Pairing the manifold with a 650 CFM carburetor creates a different balance than using a larger carburetor. The 650 CFM unit can provide adequate airflow for many appropriately matched combinations while retaining adjustable secondary response, but final sizing still depends on actual engine airflow demand.

The manifold's listed RPM range describes its intended operating characteristics; it is not a safe engine-speed guarantee. Maximum engine RPM must be established from the rotating assembly, valvetrain, cylinder heads, camshaft, oiling system, ignition control, and calibration.

LS1 LS2 LS6 Cathedral-Port Fitment

This LS carburetor intake is designed around compatible GM LS Gen III and Gen IV engines equipped with LS1, LS2, or LS6-style cathedral-port cylinder heads. Compatible combinations may include 5.7L LS1 and LS6 engines, 6.0L LS2 engines, and other verified cathedral-port LS configurations.

Reference applications may include Corvette C5, Camaro, Firebird / Trans Am, Pontiac GTO, Cadillac CTS-V, Chevrolet SSR, Holden Monaro / Commodore / HSV, and LS-swapped vehicles using a compatible engine and cylinder-head configuration.

Do not determine fitment from the vehicle model or LS engine name alone. Engine swaps and cylinder-head changes can alter intake compatibility. Confirm the actual intake-port architecture installed on the engine before ordering.

Not compatible with LS3, L92, L99, or L76 rectangular-port cylinder heads unless compatible cathedral-port heads have been installed.

What Else Is Needed for an LS Carburetor Conversion?

An LS carburetor conversion requires more than replacing the EFI intake manifold. The carburetor controls airflow and fuel metering, but compatible ignition control, carburetor-pressure fuel delivery, mechanical linkage, choke operation, vacuum connections, and installation clearance still need to be established separately.

Package Contents

Additional Parts to Check Before Ordering

The exact installation parts depend on the engine and vehicle configuration. Check whether the build requires:

• Compatible LS ignition controller
• Intake manifold and carburetor gaskets
• Carburetor-compatible fuel pump and/or fuel pressure regulator
• Fuel filter, fuel lines, fittings, and adapters
• Throttle cable bracket and return springs
• Transmission kickdown or TV cable components where applicable
• Manual choke cable
• Vacuum and PCV fittings
• Air cleaner assembly
• Carburetor spacer or adapter if required by the final installation

Before Installation

• Confirm the cylinder heads: Verify LS1, LS2, LS6, or another compatible cathedral-port configuration.
• Check intake fitment: Verify intake-port alignment, bolt pattern, and intake gasket compatibility.
• Check the carburetor interface: Confirm mounting pattern, gasket, studs, and whether a spacer or adapter is required.
• Plan ignition control: Establish the ignition-control strategy before converting from EFI to carburetor operation.
• Verify the fuel system: Confirm the pump, regulator, filter, lines, fittings, and operating pressure are appropriate for carburetor operation.
• Check throttle operation: Verify throttle cable, bracket, return springs, and transmission linkage through the full range of travel.
• Check manual choke operation: Confirm cable routing and full choke travel.
• Check vacuum connections: Identify required PCV, brake-booster, and accessory vacuum ports before startup.
• Check clearance: Include the manifold, carburetor, spacer or adapter, and air cleaner when checking hood and surrounding engine-bay clearance.

Initial Setup & Tuning

A high performance carburetor still requires the supporting systems and initial setup to be correct before metering changes are made. Final calibration depends on the complete engine combination.

1. Inspect the intake manifold, carburetor base, vacuum connections, and fuel connections for leaks.
2. Confirm that fuel pressure and fuel delivery are suitable for carburetor operation.
3. Verify ignition control and timing operation.
4. Check throttle and manual choke movement through their full range.
5. Set and evaluate idle speed and idle mixture after the engine reaches operating temperature.
6. Evaluate throttle transition and secondary response before changing metering components.
7. Adjust the air valve secondary response only after the basic engine and fuel-system conditions have been verified.
8. Change one calibration variable at a time and record the result.

Rich, lean, bogging, unstable-idle, or hard-start conditions should not automatically be treated as a carburetor jetting problem. Check for vacuum leaks, incorrect fuel pressure, fuel-delivery restrictions, float or needle-seat problems, ignition faults, and timing issues before changing carburetor calibration.

Brand Summary

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