Product Description
Michigan Motorsports LS1 MLS Head Gasket and 2004+ Head Bolt Kit – Pair – 3.920" Bore .051" Thickness
Fits 4.8L 5.3L 5.7L LS-Based Engines – Replaces GM 12589226 / 12498544
The Michigan Motorsports LS1 Head Gasket and Bolt Kit is the go-to solution for properly sealing your cylinder heads during a rebuild or camshaft upgrade. This kit includes two high-quality MLS (Multi-Layer Steel) LS1 head gaskets along with a full set of 2004+ style head bolts, giving you everything needed to get your LS engine back together with confidence.
These MLS gaskets are widely regarded as one of the best all-around choices for most LS builds. They are a direct replacement for LS1/LS6 GM head gaskets and are produced to OEM-level standards, ensuring proper fitment, sealing integrity, and long-term durability for both stock and performance applications.
NOTE: On these engines it is highly recommended to clean out the head bolt threads in the block with a chaser such as ARP 912-0011 (click here) due to the thread compound that was used on the factory bolts. Failure to do so can result in new fasteners stretching or breaking before reaching final torque.
Kit Includes
- (2) Michigan Motorsports LS1 MLS Head Gaskets – Replaces GM 12589226 / 12498544
- 2004+ Style Head Bolts (Shorter Uniform Length Design)
Head Gasket Specifications
- Bore Size: 3.920"
- Compressed Thickness: .051"
- Construction: MLS (Multi-Layer Steel)
Key Features & Benefits
- Proven LS1/LS6 Replacement Design: Direct replacement for factory GM LS1 and LS6 head gaskets, making it an ideal choice for stock rebuilds and performance upgrades.
- High-Quality MLS Construction: Multi-layer steel design provides excellent sealing under high cylinder pressure and increased heat common in modified LS engines.
- Optimized for 4.8L, 5.3L & 5.7L Builds: Ideal bore size and thickness for common LS combinations, including naturally aspirated and mild power-adder setups.
- Updated 2004+ Bolt Design: Includes the later short-length head bolt configuration introduced by GM in 2005 for consistent clamping force and simplified installation.
- Complete Reseal Solution: Everything required to properly secure both cylinder heads during a cam swap, refresh, or full engine rebuild.
Important Note on Head Bolt Style
Prior to 2004, Gen 3 and Gen 4 GM small block engines used head bolts of varying lengths. Beginning in 2005, GM transitioned to a shorter, uniform-length bolt design. Please verify which head bolt style your engine requires before ordering to ensure proper fitment.
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Great product
Parts came in time. Great Quality.
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Parts packages are amazing
Package deals and great guidance by reps.
