The Standard-Bearer for GM Reliability

A Proven Workhorse with Massive Low-End Torque

GM's Most Trusted V8 Replacement

High-Flow Vortec Heads Unleash Superior Air Delivery

Largest Selection of L31 Vortec 350 Engines in the Country

WE HAVE L31's IN STOCK - ORDER NOW!

In Stock and Ready to Ship!

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Big Horsepower

Up to 255 HP

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Big Torque

Up to 330 lb.-ft.

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Perfect Displacement

Up to 350 cu. in. (5.7L)

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Torque-Rich Power

Delivers serious torque at a low 2,800 RPM, giving you the immediate low-end grunt needed for towing, hauling, and truck applications.

Built to Last

With a rugged cast-iron block, 4-bolt mains, and a forged steel crankshaft - the GM L31 LD Crate Engine a significant durability upgrade over standard 2-bolt main cores.

KARL L31 Cast-Iron Block
KARL High Flow Vortec Cylinder Head

Legendary Vortec Airflow

Features high-flow Vortec cylinder heads - some of the best production small-block heads ever made - that optimize airflow for superior efficiency and power.

Modern Reliability

A hydraulic roller camshaft and a one-piece rear main seal help this engine reduce internal friction and eliminate the common oil leaks found in older vintage small blocks.

KARL L31 Vortec 350
KARL L31 Vortec 350 Crate Engine Icon

Ready to Install

This long-block Vortec 350 L31 Crate Engine package from Karl Kustoms arrives with the oil pan, timing cover, valve covers, and harmonic balancer pre-installed.