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Valve Spring Pocket Cutter for Gx200/Clone & Predator w/5.5mm Pilot
Valve Spring Pocket Cutter Kit with 5.49 pilot
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Valve Spring Pocket Cutter for Gx200/Clone & Predator w/5.5mm Pilot

Part Number: 290-95BK
Online Price: $169.99
Precision Valve Spring Pocket Cutter for Honda Clone 5.5mm Guides
Availability: Out of Stock.

Description

EC Pocket Cutter Tool for 5.5mm Guide Honda Clone Cylinder Heads


Precision Valve Spring Pocket Cutter for Performance Cylinder Head Setup

The EC Pocket Cutter Tool is designed specifically for small-block Honda-clone cylinder heads equipped with 5.5mm valve guides. This tool allows engine builders and performance enthusiasts to cut precision spring pockets into the cylinder head, enabling the use of dual valve springs and optimizing the installed spring height — a critical step in building high-RPM, high-performance small engines.


Whether you're preventing coil bind or fine-tuning spring seat pressure for your specific cam and RPM requirements, this cutter gives you the control needed for professional-grade valve train setup.


Key Features & Benefits:

  • Designed for 5.5mm Valve Guides: Equipped with a 5.45mm pilot for tight alignment in cylinder heads using 5.5mm valve guides.
  • Spring Pocket Customization: Opens the spring pocket to the correct outer diameter for dual springs, while setting optimal install height.
  • Avoid Coil Bind: Helps ensure .040”+ clearance before spring coil bind, protecting your valve train from catastrophic failure.
  • Tune Spring Seat Pressure: Adjust the install height to influence valve spring seat pressure across the lift curve — critical for matching cam profiles, RPM range, and valve train weight.
  • Precision Geometry: Maintains consistent pocket size and depth for proper spring seating and valve train stability.


Why Spring Install Height Matters:

Correct install height ensures that your valve springs perform within their designed pressure ranges. For example:

  • 32 lb. Dual Valve Springs:
    • ~32 lb at .930” install height
    • ~45 lb at .815” install height

This change directly impacts valve control at various RPM levels and lift values. Matching your spring pressure with your cam profile, rocker geometry, and total valve train mass is essential to avoid valve float, spring surge, or mechanical failure.


Notes on Usage:

  • Only cuts the floor of the spring pocket — not intended for sidewall or rocker boss modifications.
  • Hemi Head Compatibility: Some hemi-style heads may require additional clearance around the rocker stand/boss. Do not use this cutter for that purpose — use proper machining methods instead.
  • Always verify coil bind clearance and spring rate post-machining.


Cutter Kit Specifications:

  • Pilot Diameter: 5.45mm (for 5.5mm valve guides)
  • Cutting Outer Diameter (OD): 0.985"
  • Cutting Inner Diameter (ID): 0.600"


If you're building a performance mini bike, kart, or racing engine, this is an essential tool for precision valve train setup

FAQ

1. What engines is this pocket cutter compatible with?

This cutter is specifically designed for small block Honda-Clone engines (such as GX200, Predator 212, Tillotson 212, Ducar 212) with 5.5mm valve guides. Always verify the valve guide size before use.


2. What does this cutter actually do?

It cuts precise pockets into the cylinder head to fit dual valve springs and adjusts the installed spring height — critical for ensuring proper spring pressure, avoiding coil bind, and matching your camshaft specs.


3. Why is adjusting spring install height important?

Installed height affects spring pressure. For example, a 32-lb spring at a .930" height may deliver 45 lbs at .815". This affects valve control, preventing float and ensuring power delivery across the RPM range.


4. Can I use this on hemi heads?

Yes, but note that some hemi-style heads may have interference near the rocker stand. The cutter is not designed to machine these areas. Use proper milling tools if additional clearance is required.


5. Can this tool cut sidewalls or rocker boss areas?

No. This cutter only machines the floor of the spring pocket. It is not meant for rocker boss reliefs or sidewall machining. Attempting this can damage the tool and cylinder head.


6. What pilot size does the cutter use?

It comes with a 5.45mm pilot, ideal for valve guides measuring 5.5mm ID.


7. Do I still need to measure coil bind after cutting?

Absolutely. Even after cutting, you must verify you have at least .040" clearance before coil bind. Always test-fit springs and use precision measuring tools to confirm.

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