Engines and Components› Crankshafts and Components

Molnar Technologies

4340 Forged Steel Crankshaft, 3.875" Stroke

$1,020.75

SKU: MOL-400-3875CB6F-585

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Overview

The Molnar Technologies crankshaft is a 4340 forged steel component designed for SB Chevy engines. It features a 3.875-inch stroke, 400 main, 2.100-inch rod journal, and is internally balanced. The crankshaft is heat-treated for tensile strength, shot-peened for fatigue life, and nitrided for wear resistance. It is also 100% mag particle inspected to ensure against cracks, with all Molnar cranks held to tight tolerances.
Show original supplier description
The Molnar Technologies crankshaft is meticulously crafted from 4340 forged steel, a material chosen for its exceptional strength and durability in high-performance applications. Each crankshaft undergoes a rigorous heat-treating process to significantly increase its tensile strength, ensuring it can withstand extreme operating conditions. To further enhance its resilience and lifespan, the crankshaft is shot-peened, a process that refines the surface texture to improve fatigue life, and then nitrided for superior wear resistance. This specific crankshaft is designed for SB Chevy engines and features a 3.875-inch stroke, a 400 main bearing journal diameter of 2.649 inches, and a 2.100-inch rod journal diameter. The rear main seal is a two-piece design. Molnar Technologies ensures the quality and integrity of each crank through 100% magnetic particle inspection, guaranteeing against cracks and holding all components to the tightest tolerances found in the racing industry.

Product descriptions are provided by our supplier partners and may not always be perfectly accurate. Not sure this fits? or call (760) 282-4645 and we’ll verify before you order.

Fitment

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Specifications

BrandMolnar Technologies
Part NumberMOL-400-3875CB6F-585
CategoryEngines and Components
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Returns & Fitment

Built for enthusiasts. Every order is backed by our 30 day return window on eligible items. Unused and uninstalled products may be returned with approved RMA and no restocking fees when received in new condition. Orders placed through the MOTORMIA app with a complete build qualify for our Fitment Guarantee — free return shipping if the part doesn’t fit your exact setup. The guarantee covers fit only; installation must follow manufacturer instructions, and we recommend a qualified shop for parts marked Difficulty 4–5.

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Shipping

Orders are processed in 1–3 business days. In stock parts ship promptly from our partner network. Special-order items either aren’t currently stocked or are built to your spec — expect 4–6 weeks. If a part goes on backorder while your order is in the queue, we’ll reach out and work through discounted alternatives together.

Free shipping over $200 in the continental US. Alaska, Hawaii, U.S. territories (Puerto Rico, U.S. Virgin Islands, Guam, American Samoa, and the Northern Mariana Islands), and international orders carry surcharges — most appear at checkout. Some exceptions (LTL freight, or suppliers who quote freight only after we place the order) won’t. In those cases we’ll reach out with the exact charge before your order moves forward.

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