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Schley Tools 88800 valve adjustment tool for 12mm jam nut

Schley Products, Inc

Schley Products, Inc 88800 Valve Adjustment Tool 12mm Jam Nut

SKU CH-GCA4-Q04KG

Valve adjustment tool with a 12 mm jam nut for precise engine valve lash setting

  • Designed for 12mm jam nuts on valves
  • Precision adjustment tool for engine maintenance
  • Professional-grade construction from Schley Tools
  • Manufacturer part number 88800 for exact fit
  • First listed by manufacturer on 14 February 2025

Valve Adjustment Tool 12mm Jam Nut

The Schley Products 88800 is a dedicated valve adjustment tool designed for engines that use a 12mm jam nut on the rocker assembly. It allows technicians to hold the nut while turning the adjuster screw to set precise valve lash. The tool is supplied new and ready for professional or enthusiast use.

Suited for 12mm jam nut applications

This tool suits mechanics and engine builders working on cylinder heads where the valve train uses a 12mm jam nut locking mechanism. It will not fit engines with different nut sizes, locknut styles, or hydraulic lifter designs that do not require manual lash adjustment. Buyers needing a comprehensive valve adjustment kit with multiple socket sizes or feeler gauges should look at a complete set instead.

12mm jam nut compatibility

The single specification that decides fitment is the 12mm jam nut size. Verify that the target engine uses this exact nut dimension before purchasing. The tool is manufactured by SCHLEY TOOLS and was first listed by the manufacturer on 14 February 2025.

How it compares

Measured against everything we stock in Hose Fittings, Adapters & Clamps, at today’s prices. Recalculated every night.

Price $28.99
Pricier than about 67% of the 2,955 comparable items (median $17.99).

Specifications

Product
Brand nameSCHLEY TOOLS

Questions about this item

What does the 12 mm jam-nut size mean when I am setting valve lash?

It matches the 12 mm lock nut on the rocker arm so the wrench holds the nut while you turn the adjuster.

What drive interface does the tool use and what torque can it realistically transmit?

A 14 mm hex drive fits a standard ratchet or breaker bar and handles normal valve-adjustment torque.

What physical clearance does the tool need to fit on the engine?

The compact hex body slips into the tight space around a 12 mm jam nut without contacting nearby components.

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