Chrysler 318 / 340 Steel 4-Bolt Main Cap – Strength Upgrade for High-HP Builds

🔧 Reinforce Your Chrysler Small Block Bottom End

Did you know factory 2-bolt main caps in Chrysler 318 and 340 small blocks often start to fail around 450–500 HP (335–375 kW)? At this point, the caps can walk, crack, or lose alignment — a common failure point in boosted, nitrous, and high-RPM Mopar builds. If your engine is targeting this power range, upgrading to 4-bolt steel caps is cheap insurance to keep your bottom end alive.

When chasing serious horsepower from a Chrysler 318 or 340 engine — especially with boost, nitrous, or sustained high RPM — the factory 2-bolt main caps quickly become a weak link. This steel 4-bolt main cap upgrade adds crucial strength and durability to your bottom end build.

Precision CNC-machined by Milton Engine Developments, this billet steel main cap is built for racers and engine builders demanding reliable performance under extreme load.

💪 Why Upgrade to a 4-Bolt Steel Main Cap?

• Prevents cap walk and crank shift under high load
• Cheap insurance for high-horsepower, boosted, or race engines
• Significantly improves main bearing stability

✅ Key Features:

• 1x set of 3 precision-machined steel main caps – 4-bolt configuration
• Direct upgrade for factory Chrysler 318 / 340 blocks
• Machined in South Australia by Milton Engine Developments
• Designed for maximum bottom-end strength
• Zinc-coated for corrosion resistance

📦 Fitment:

• Chrysler Small Block 318 V8
• Chrysler Small Block 340 V8
• Suits local and export applications — including A-body, B-body, and Duster/Dart builds

🔧 Installation Notes:

• Line boring/honing required after fitment
• ARP main studs or bolts recommended for installation
• Should be installed by a qualified engine machinist

🇦🇺 Proudly Made in Australia

Each main cap is precision-engineered and CNC-machined in South Australia by Milton Engine Developments — trusted by engine builders across drag, street, and track applications.

⏱️ Need It Fast? Contact us before ordering to confirm stock and turnaround time.
📩 Custom Requirements? We can manufacture billet caps and specialty components on request — just reach out.