Diesel Performance Parts
Isuzu 4JJ1 Upgraded Valve Springs and Titanium Retainer Kit
Isuzu 4JJ1 Upgraded Valve Springs and Titanium Retainer Kit
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Upgraded 4JJ1 valve springs and titanium retainers built to stop valve float on tuned Isuzu D-Max, MU-X, Holden Colorado RC and RA7 Rodeo 3.0L turbo diesels. Once you wind up the boost and RPM on a 4JJ1, the factory springs run out of seat pressure and the valves stop following the cam. This kit fixes that with roughly 120% more seat pressure than OE, and it is a true drop-in: no machining, reuses your OE collets and standard valve stem seals.
Sold as a complete engine set for all 16 valves with matched titanium retainers included. Stocked and shipped from Queensland by the crew that tests and codes 4JJ1 injectors in-house every week.
| Kit Specifications | |
|---|---|
| Engine | Isuzu 4JJ1-TC / 4JJ1-TCX (3.0L, 16 valve) |
| Spring construction | 6 coils, 4.0 mm wire, clockwise wind, OD 29.8 mm / ID 22.1 mm |
| Installed height | 37.8 mm (1.488") |
| Installed seat pressure | 44-46 kg (97-101 lb), approx 120% increase over OE springs |
| Coil bind | 24.1 mm (0.948") |
| Retainers | Titanium, matched to these springs only |
| In the box | Full engine set of springs (16 valves) plus full set of titanium retainers. Complete set only. |
| 4JJ1 Valve Spring Fitment Guide | |||
|---|---|---|---|
| Vehicle | Series | Years | Engine |
| Holden Rodeo | RA7 | 2007-2008 | 4JJ1-TC ✔ |
| Holden Colorado | RC | 2008-2012 | 4JJ1-TC/TCX ✔ |
| Isuzu D-Max | 1st gen | 2008-2012 | 4JJ1-TC ✔ |
| Isuzu D-Max | RT (2nd gen) | 2012-2020 | 4JJ1-TCX ✔ |
| Isuzu MU-X | 1st gen | 2013-2021 | 4JJ1-TCX ✔ |
| Holden Colorado / Colorado 7 | RG | 2012-2020 | 2.8L Duramax ✘ does not suit |
| Isuzu D-Max / MU-X, Mazda BT-50 | 2020 on | 2020+ | 4JJ3-TCX ✘ contact us first |
| Isuzu D-Max 2.5L | All | All | 4JK1 ✘ does not suit |
Not sure which engine you have? The engine code is stamped on the machined pad at the front of the block near the alternator, and the 8th digit of your VIN indicates the engine family. Or just SMS us your VIN and we will confirm fitment before you order.
Why Upgrade Your 4JJ1 Valve Springs?
- Helps prevent valve float in high boost and higher RPM applications with appropriate tuning
- Improves valvetrain control for safer sustained load, towing and top-end pulls
- A smart companion to bigger turbos, high flow injectors and performance tunes
- Drop-in convenience: retains factory seals and collets, no machining
Installation Notes
- Verify installed height of 37.8 mm and confirm coil bind clearance at your cam's maximum lift
- No cam upgrade required, but always check clearances if running an aftermarket cam
- Reuse OE collets and seals, replacing any that show wear
- Follow factory torque procedures for cam caps and rockers
- Professional installation recommended
Warranty & Returns
Covered by our standard warranty and returns policy. Full terms here: Refund & Warranty Policy.
Shipping
Free express shipping Australia-wide with tracked dispatch. Afterpay, Humm, Klarna and Zip available at checkout.
Building a full setup? Browse the rest of our Isuzu 4JJ1 performance parts and upgrades, including injectors, turbos and fuel system gear, all from the same Queensland workshop.
