Cylinder Base Nut Wrench Set – 4-Piece | Continental & Lycoming Engine Tool

Be prepared for a wide range of cylinder maintenance jobs with this professional-grade 4-Piece Cylinder Base Nut Wrench Set. Designed for servicing Continental, Lycoming, and other compatible engines, the set includes the four most useful cylinder base nut sizes: 1/2", 9/16", 5/8", and 3/4".

Each wrench features a 15-inch span for reaching around engine cylinders and an extra-thin 0.14" wall for accessing cylinder base nuts in tight locations. The 12-point end works with both hex and 12-point nuts, while the 1/2" square drive allows use with compatible torque wrenches and breaker bars.

Forged from 4130 steel, tempered for strength, and finished with industrial chrome plating, this set is built for professional engine maintenance, cylinder changes, top-end work, and complete overhauls.

Set Includes

• (1) 1/2" Cylinder Base Nut Wrench
• (1) 9/16" Cylinder Base Nut Wrench
• (1) 5/8" Cylinder Base Nut Wrench
• (1) 3/4" Cylinder Base Nut Wrench

Product Features

• Complete 4-piece wrench set
• Hex Sizes: 1/2", 9/16", 5/8" & 3/4"
• 1/2" square drive
• 15" (381 mm) span
• Extra-thin 0.14" (3.5 mm) wall
• 12-point ends fit both hex and 12-point nuts
• Long-reach design fits around most engine cylinders
• Designed for tight cylinder base nut locations
• Forged from high-strength 4130 steel
• Tempered for maximum strength and durability
• Industrial chrome plating improves surface hardness and corrosion resistance
• Quality tested to meet or exceed engine manufacturer torque specifications

Engine Applications

Designed for cylinder service on a broad range of Continental and Lycoming engines using compatible cylinder base nuts.

Continental:
Most applications use 1/2" or 9/16" cylinder base nuts. O-470 and IO-520 applications commonly require the 5/8" wrench, with some configurations also utilizing 9/16" hardware. Select older Continental engines may require the 3/4" wrench.

Lycoming:
Designed for compatible Wide Deck applications, which most commonly utilize the 3/4" wrench.

Fitment Note: Engine hardware can vary by model, configuration, crankcase, and previous modifications. Verify your cylinder base nut size before use.

Ideal for Engine Maintenance

This complete set is ideal for:

• Cylinder removal and installation
• Cylinder replacement
• Top-end overhauls
• Complete engine overhauls
• Cylinder base nut removal
• Cylinder base nut installation and torquing
• Engine teardown and assembly

Important Torque Note

When using these wrenches with a torque wrench, the effective extension length can affect the actual torque delivered to the cylinder base nut. Follow the applicable engine manufacturer's torque procedure and apply the appropriate torque correction when required.

Airboat Solutions

For shops and airboat owners working on multiple Continental and Lycoming engine families, the complete four-piece set eliminates the need to purchase individual cylinder base wrenches as different engine projects come through the shop.

Set: 4 Pieces
Sizes: 1/2" • 9/16" • 5/8" • 3/4"
Drive: 1/2" Square
Span: 15" (381 mm)
Material: Forged 4130 Steel
Finish: Industrial Chrome Plated