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Head Bolt Kit - 1997–2015 4.8L-6.2L Chevrolet Gen III/IV LS (Hex 6-Point)
PART # SKU XP987
Original price
£132.00
-
Original price
£132.00
Original price
£132.00
£132.00
-
£132.00
Current price
£132.00
Availability:
in stock, ready to be shipped
ULTRA STRENGTH
In comparison to standard bolts, our alloy's material characteristics enable much higher tensile strength. For the best fatigue strength, threads are rolled after thermal treatment. A high-quality coating can improve corrosion resistance, reduce friction, and improve overall performance.
EASY INSTALLATION
Installation manual is included with drawn diagrams to ease the installation process. Our head bolts are designed to retain cylinder seal even with today's extremely high-pressure turbo systems.
PREMIUM QUALITY
Black oxide finish protects from wear and tear. Hardened parallel washers allow for uniform load distribution and accurate torque readings.
INSTALL GUIDE
This guide covers installation of the XOTIC PERFORMANCE™ XP987 hex head bolt kit for 2003-and-earlier Chevrolet Gen III LS engines (4.8L, 5.3L, 6.0L, 6.2L). Prefer a printable copy? Download the PDF manual.
Two LS head bolt kits — check your model year. XP987 (this kit) is for 2003-and-earlier Gen III LS engines. For 2004+ Gen III/IV engines with same-length primary bolts, you want the XP981 kit and guide. GM changed the head bolt design in 2004 — confirm your engine before ordering.
Why upgrade your LS head bolts
Factory LS head bolts are torque-to-yield and single-use — once the heads come off, they're done. If you're replacing them anyway, this is the moment to step up. Cam swaps, nitrous, and boost all raise cylinder pressures well past what the stock hardware was designed to hold, and when the clamping force securing the gasket, head, and block is no longer sufficient, the head gasket lets go.
XOTIC PERFORMANCE™ head bolts are manufactured from our premium XOTIC 7200 steel alloy — far higher tensile strength than standard hardware — and backed by a lifetime warranty. Bolts are the right call when you want strong clamping with the convenience of pulling a head in the chassis without fighting stud clearance. For maximum clamping on a serious boost build, see our early LS head stud kit (CP887) and guide. Either way, the key is accurate preload: the tensile force generated when a fastener is tightened, creating clamp force in the joint. Everything in this guide is in service of achieving equal, accurate preload across all 30 bolts.
What's in the XP987 kit
- 30 × hex head bolts (XOTIC 7200 alloy) — 11mm primary and 8mm secondary
- 30 × hardened parallel washers
- 2 × sockets
- 1 × fastener assembly lubricant
Before you start: verify first
Confirm that part number XP987 is compatible with your application before installing any components. Inspect all package contents for damage and clean as necessary to ensure accurate installation. Report any obvious defects or shipping damage to us before proceeding.
How to install head bolts on an early LS
- Clean the block threads. Clean the threads in the block prior to installing the bolts to ensure accurate fitment and precise torque readings. Dedicated chasers make this fast: M11 x 2.00 (CS324) for the primary holes and M8 x 1.25 (CS317) for the small ones.
- Clean the washers and seats. Using a clean cloth, remove all oil from the washers and from the cylinder head surfaces where the washers sit. Clean, dry seating surfaces are essential for accurate preload.
- Set the gasket and head. Install the head gasket and cylinder head.
- Seat the washers — chamfer up. Place the washers on the cylinder head with the chamfered inner diameter facing upward, toward the bolt head. Inspect for any misalignment.
- Lubricate. Using the supplied fastener assembly lubricant, coat the threads of each head bolt and the underside of each bolt head.
- Hand-tighten. Thread the bolts in as tight as can be made by hand.
- Torque in sequence. Follow the torque stages below in the numbered sequence shown in the manual's torque sequence diagram, then repeat on the second bank.
Early LS head bolt torque specs
11mm bolts (positions 1–10)
| Stage | Torque |
|---|---|
| 1 | 30 ft-lbs |
| 2 | 55 ft-lbs |
| 3 (final) | 80 ft-lbs |
8mm bolts (positions 11–15)
| Stage | Torque |
|---|---|
| Final | 25 ft-lbs |
A common mistake to avoid: when torquing a fastener, do not stop short of the recommended value — continue in one motion until the specified torque is achieved. If you accidentally stop short, loosen the fastener and re-torque. Stopping short and "topping up" produces unequal preload distribution across the bolts and risks joint failure.
Frequently asked questions
What are the torque specs for early LS head bolts?
The 11mm bolts (positions 1–10) go to 30, then 55, then 80 ft-lbs in sequence. The 8mm bolts (positions 11–15) torque to 25 ft-lbs.
Which LS engines does the XP987 kit fit?
2003-and-earlier Chevrolet Gen III LS engines. For 2004+ engines, use XP981.
Head bolts or head studs for an early LS?
Bolts let you pull a head in the chassis without dealing with stud clearance — ideal for street builds and cam swaps. Studs deliver maximum clamping for serious boost. If you're going the stud route, see the CP887 head stud guide.
What size thread chasers do I need?
Two: M11 x 2.00 (CS324) for the primary bolt holes and M8 x 1.25 (CS317) for the small ones.
Need help?
For technical support, email support@xotic-performance.com. All XOTIC PERFORMANCE™ fasteners are covered by our limited lifetime warranty. Finished your install? Tag #XOTICPERFORMANCE on Instagram for a chance to be featured.
© 2026 XOTIC PERFORMANCE™. This installation guide is an original copyrighted work of XOTIC PERFORMANCE™. Reproduction, distribution, or use of this content in whole or in part without written permission is prohibited. Doc ref: 2026.01.31 (web edition 2026.08).
PACKAGE CONTENTS
VEHICLE FITMENTS
⚠️ PROP 65 WARNING
CALIFORNIA WARNING: Cancer and Reproductive Harm -www.P65Warnings.ca.gov
