Chevrolet Corvette 427/435 Intake Manifold, Holley Carburetors, and Air Cleaner

1967–1969 Chevrolet Corvette L71 (427ci/435hp) is one of the most famous setups in muscle car history. Known as the “Tri-Power” system, it utilized three two-barrel carburetors to provide massive airflow at full throttle while remaining relatively streetable at lower speeds.

1. The Intake Manifold

The L71 utilized a high-rise aluminum intake manifold designed for rectangular-port cylinder heads.

• Casting Number: 3894374 (most common for 1967) or 3919852 (for 1968–1969).

   

• Material: Cast Aluminum.

• Key Identification: Original units feature the “Winter’s Snowflake” logo (a small snowflake-shaped casting mark) indicating the Winter’s Performance Products foundry that cast them for GM.

   

• Design: A “3×2” configuration with three distinct mounting pads for the Holley two-barrel carburetors.

2. The Holley Carburetors

The Tri-Power setup consists of a central primary carburetor and two outboard secondary carburetors.

• Total Airflow: Approximately 1,282 CFM.

• Operation: Under normal driving, you only run on the 350-CFM center carburetor. When the throttle passes roughly 60%, vacuum diaphragms pull the two outboard carburetors open, unleashing the full 435hp.

• Finish: Original units featured a distinct Gold Dichromate finish to prevent corrosion.

   

3. The Air Cleaner Assembly

Because of the triangular arrangement of the three carburetors, the air cleaner has a very specific “triangular” or “shovel” shape.

• Lid: Chrome-plated steel with a triangular footprint.

• Base: Deep-drop steel base designed to clear the high-rise manifold and fit under the Corvette’s “Stinger” (1967) or “L88/Power” (1968-69) hood.

• Filter: A unique reusable polyurethane foam element supported by a metal mesh screen.

   

• Decals: Features the “Turbo-Jet 427” cross-flag logo and a separate “435 HP” sticker.