• Isuzu 4JJ1 Upgraded Valve Springs and Retainer Kit - Common Rail Cowboys
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Diesel Performance Parts

Isuzu 4JJ1 Upgraded Valve Springs and Retainer Kit

Isuzu 4JJ1 Upgraded Valve Springs and Retainer Kit

$930.00 NZD
$930.00 NZD
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Isuzu 4JJ1 Upgraded Valve Springs & Titanium Retainer Kit

🚚 Free Express AU 💳 Afterpay • Humm • Klarna • Zip 🧩 Drop-In Upgrade

4JJ1 performance valve springs and titanium retainers to suit Isuzu 4JJ1TC engines. A true drop-in: no machining, uses standard valve stem seals and OE collets. Built for tuned engines that need higher seat pressure and stability at RPM/boost.

🔥 Why Upgrade?
  • Prevents valve float in high boost / higher RPM applications
  • Improves valvetrain control for safer power at sustained load
  • Drop-in convenience — retains factory seals and collets
📐 Kit Specifications
  • Spring construction: 6 coils, 4.0 mm wire, clockwise
    OD 29.8 mm / ID 22.1 mm
  • Installed height: 37.8 mm (1.488")
  • Installed seat pressure: 44–46 kg (97–101.4 lb)
  • Increase over OE ute/pass springs: ~120%
  • Coil bind: 24.1 mm (0.948")
  • Retainers: Titanium — use only with these springs
🔧 Vehicle/Engine Suitability
  • Isuzu 4JJ1TC (16-valve) engines

Note: Designed for 4JJ1 valvetrain geometry. If unsure, message us with VIN/engine code.

📦 What’s Included
  • Full engine set of upgraded valve springs (for 16 valves)
  • Full set of titanium retainers matched to these springs

Only sold as a complete set.

🛠️ Install Notes
  • Verify installed height = 37.8 mm and coil-bind clearance at full lift
  • Reuse OE collets and seals; replace if worn
  • Follow factory torque procedures for cam caps/rockers
  • Professional installation recommended
💳 Payment & 🚚 Shipping
  • Afterpay, Humm, Klarna & Zip available
  • Free Express Shipping Australia-Wide — fast, trackable dispatch

❓ FAQs

Do I need machining or different seals/collets?
No — this is a drop-in kit that uses standard valve stem seals and OE collets.
Will this help with valve float at higher boost?
Yes. The increased seat pressure and rate improve control and reduce valve float in tuned/high-boost applications.
Can I use the titanium retainers with stock springs?
No. Retainers are matched to these springs and should not be mixed with OE springs.
What engines does this suit?
Isuzu 4JJ1TC (16-valve). Message us with VIN if you need confirmation.
Is cam upgrade required?
Not required. Ensure coil-bind clearance at your cam’s maximum lift and verify installed height.
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