4J Head Bolt Set - 4JJ1 / 4JK1 / 4JJ3 - Fuse Tech

The torque figures belong to the bolt, not the engine, so the procedure is the same on every engine this set fits. Follow the factory tightening sequence from the Isuzu workshop manual (centre outwards).

1. Clean the block threads to full depth with an M11 x 1.5 thread chaser (not a cutting tap). Blow every hole out with compressed air. Oil or coolant left in a blind hole can hydraulic the bolt, crack the block, or give a false torque reading.
2. Fit the head gasket dry over the locating dowels, then lower the cylinder head straight down. Do not slide it.
3. Lightly oil the bolt threads and the underside of the bolt head with clean engine oil. Wipe off the excess. Do not use ARP Ultra-Torque, moly paste or anti-seize. They change the friction and will over-tension the bolt at these figures.
4. Run all 18 bolts in finger tight. Any bolt that binds before it seats comes out for a clean.
5. Tighten in the factory sequence in three passes:

6. Go around once more at 120 ft-lb in sequence to confirm every bolt holds. No angle tightening.
7. No hot retorque unless your engine builder specifies one.

Why engine oil only: the same torque number gives a very different clamp load depending on what is on the threads. ARP Ultra-Torque at 120 ft-lb pulls roughly 30% more preload than engine oil does, which is past where these bolts should be loaded. Pick engine oil, print it on your build sheet, and do not mix.

• Full 18 bolt set: every head bolt for one engine, one box, done
• Whole 4J family: one set covers 4JJ1, 4JK1, 4JX1 and 4JJ3
• Direct fit: threads into the factory M11 x 1.5 block threads, unlike stud kits which need the block tapped deeper and clearance work under the rockers
• Torque only: a straight three-pass torque procedure, no angle gauge, no guessing
• Fit while you are in there: factory bolts must be replaced any time the head is removed, so upgrading costs zero extra labour

• Isuzu D-MAX, 4JJ1-TC / 4JJ1-TCX (2007 to 2020, incl. DPF models)
• Isuzu D-MAX RG / MU-X, 4JJ3 (2020 on)
• Isuzu MU-X, 4JJ1-TC / TCX (2013 to 2021)
• Holden Colorado RC / Rodeo RA7, 4JJ1-TC
• Mazda BT-50 TF, 4JJ3 (2020 on)
• Isuzu D-MAX 2.5, 4JK1 | Jackaroo / Trooper, 4JX1

Not sure? Isuzu used the same 18 bolt head fastener design across the common rail 4J family, so there is no early/late split. Send us your VIN or State and Rego and we will confirm before you order.

• 18 x FuseTech heavy duty cylinder head bolts

Not included: head gasket. Always fit a new head gasket, graded to piston projection per the workshop manual, whenever the cylinder head is refitted.

Studs deliver maximum clamp, but the 4JJ1 stud install means tapping the block threads deeper and machining clearance where the outer studs sit under the rocker assembly. These bolts are a straight drop-in. They suit builds that want an upgrade over factory fasteners without the machining.

If you want the stud route, see the 4JJ1 ARP2000 Head Stud Kit.

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What torque do I use?
Three passes in the factory sequence: 80, then 110, then 120 ft-lb (108, 149, 163 Nm), with clean engine oil on the threads and under the bolt head. Torque only, no angle step. See the full procedure above.

Can I use ARP Ultra-Torque or moly lube instead of oil?
No. The torque figures are written for engine oil. ARP Ultra-Torque at the same torque pulls roughly 30% more preload and will over-tension the bolt. Engine oil only.

Do I follow the Isuzu torque-plus-angle procedure?
No. That procedure is for the factory torque-to-yield bolts. These bolts use the three-pass torque procedure on this page.

Will these fit my 2012 to 2019 D-MAX 4JJ1?
Yes. This set fits every common rail 4JJ1, from early alloy rocker cover engines through to the DPF-era 4JJ1-TCX, plus the 4JK1, 4JX1 and current 4JJ3.

What OE part number do these replace?
Isuzu 8-98201019-0, which superseded 8-97144583-0, -1 and -2. A full set is 18 identical bolts.

Can I reuse my factory head bolts instead?
No. Factory bolts are torque-to-yield and single use only. Isuzu specifies new bolts every time the head is fitted, which makes head work the perfect time to upgrade.

Why upgrade head bolts on a tuned 4JJ1 or 4JJ3?
More boost and fuel means more cylinder pressure pushing up on the head. Upgraded fasteners help maintain head gasket clamp on hardworking tuned engines. Cheap insurance compared to a lifted head.