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EC Big Valve 37.5/32mm Cylinder Head for GX390, Predator 420 & Clone Engines
Big Valve 37.5/32mm Cylinder Head for Big Block Honda-Clone Engines
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EC Big Valve 37.5/32mm Cylinder Head for GX390, Predator 420 & Clone Engines

Part Number: 188F-11200-1K
Online Price: $299.99
Phone Order Price:$349.99
You Save:$50.00(14%)
EC Big Valve Cylinder Head for GX390, Predator 420 & Clone Engines
Availability: In Stock.

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Description

EC Big Valve Performance Cylinder Head for GX390, Predator 420, Wildcat 460 & Big Block Clones


Unlock the full potential of your big block clone engine with EC’s Big Valve Cylinder Head, engineered to deliver superior airflow, increased power, and reliable high-RPM performance. Designed to fit Honda GX390, Predator 420/459, Wildcat 460, and other 420cc+ clone engines, this head is a must-have upgrade for serious performance builders.


Recognizing that real power starts in the cylinder head, EC set out to create a high-flow cast head tailored for engines running aggressive camshafts, high-ratio rockers, and stronger valve springs. The result is a precision-machined wedge-style cylinder head with oversized valves and a valvetrain setup built to handle up to .420” lift.


Performance Features & Benefits

  • Oversized Valves for Maximum Flow
    • 37.5mm intake & 32mm exhaust dramatically improve airflow
  • 6.5mm Valve Stems with 6mm Tips
    • Allows use of EC’s lightweight 6mm titanium retainers and locks
  • Performance-Spec Valve Springs Included
    • Handles up to .420” cam lift
    • Pre-installed for easy bolt-on installation

Fitment Note: This head uses a standard wedge-style 420cc head design with a single valve cover bolt. Make sure you have the correct valve cover and hardware before purchasing.


Valve Spring Specs (Installed)

  • Install Height: 1.150"
  • Seat Pressure (Closed): 70 lbs
  • Open Pressure at .730" (.420 Lift): 147 lbs
  • Coil Bind: 0.690"


Why Choose the EC Big Valve Head?

The stock cylinder head quickly becomes a bottleneck once performance parts like cams and high-ratio rockers are added. EC’s Big Valve Head removes that restriction, offering:

  • Greater airflow for better combustion and torque
  • Compatibility with high-lift camshafts
  • Reliability under extreme RPM conditions
  • Drop-in fit for most big block clone engines

FAQ

What engines does this cylinder head fit?

This head fits most big block Honda clone engines, including the GX390, Predator 420/459, and Wildcat 460. It uses a wedge-style configuration with a single valve cover bolt.


Can I use my stock retainers and locks?

No. This setup requires 6mm retainers and locks, which are included with EC’s titanium retainer kits. The valves have 6.5mm stems with 6mm undercut tips for this compatibility.


Is this head ready to install?

Yes. Each head is preassembled with valve springs and retainers capable of supporting up to .420” lift, making it a bolt-on upgrade for most performance applications.


Do I need to change my valve cover?

Possibly. This head uses a single-bolt valve cover design. Please verify your engine’s cover compatibility before purchase.

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