Underdrive Pulley 4" | Single Groove | 20R/22R/RE/RET

Underdrive Pulley

Maximize your engine's efficiency and free up hidden horsepower with our premium 4" Single-Groove Underdrive Pulley. Engineered specifically for high-RPM race applications, this ultra lightweight pulley reduces the drag on your engine by underdriving your belt accessories, allowing the engine to rotate with significantly less effort.

Crafted in the USA from premium T-6 6061 billet aluminum, this pulley replaces the heavy, 5-pound, 6" factory steel harmonic damper. By shrinking the diameter to 4" and cutting the weight down to just half a pound, you drastically reduce rotational mass while cleaning up your engine bay.

Key Features

• Built-In Degree Wheel: Features precision, laser-etched degree markings on the face of the pulley to help you dial in Top Dead Center (TDC) with absolute accuracy.
• Race-Proven Durability: CNC-machined from American T-6 6061 billet aluminum and hard anodized to withstand harsh track conditions.
• Single-Groove Design: Strictly intended for dedicated race setups running an alternator only, with no power steering, A/C, or extra belt-driven accessories.

Recommended  Additional Parts: 

• Crankshaft Oil Seal: Part number 1015042
• Adjustable Timing Tag: Part number 1016117

Need a Different Configuration?

If your engine requires additional accessory belts, we offer multi-groove variants and comprehensive setups:

• Double Groove Pulley (Alternator & A/C or custom accessory; no power steering): See part number 1016104.
• Triple-Groove Pulley (Alternator, A/C, and Power Steering): See part number 1016105.
• Complete Underdrive Kits: See part numbers 1016120, 1016123, 1016124.

• 1975-1980 20R 2.2L Engines
• 1981-1995 22R 2.4L Engines
• 1983-1995 22RE 2.4L Engines
• 1985-1988 22RET 2.4L Engines

CLICK HERE to download a printable PDF version of these instructions.

Installation Overview

The LC Engineering 4-inch underdrive crankshaft pulley installs exactly like your stock factory pulley. However, due to the modified dimensions, you must trim the factory timing tag on the oil pump to ensure proper belt clearance.

LC Engineering strongly recommends reviewing your factory service manual before beginning. If you have any questions during the installation process, please contact our Technical Support Line at 928-855-6341.

Step-by-Step Guidelines & Recommendations 

• Timing Tag Modification: To ensure proper belt clearance, the factory timing tag on the oil pump must be trimmed off. Because of this, we highly recommend upgrading to our Adjustable Timing Tag (Part number:1016117).
• Crankshaft Oil Pump Seal: The front crankshaft oil pump seal rides directly on the pulley hub. We strongly recommend installing a fresh Crankshaft Oil Seal. (Part number: 1015042) during this installation.
• Pre-Lubrication: Always apply a thin coat of fresh motor oil to both the new seal lip and the pulley's sealing surface prior to installation to prevent a dry start.
• Woodruff Key Inspection: Ensure the crankshaft key is properly seated in the keyway and in excellent, undamaged condition before sliding the new pulley into place. 
• Torque Specifications: Tighten the front crankshaft bolt to a final torque of 80 ft-lbs.