Shielded Spark Plug Adapter Kit For 24V Military Ignition Cables
Correct fit for Dodge M-Series, Jeep M38/M38A1, and other 24V waterproof systems.

This adapter kit allows you to retain your original 24V military waterproof ignition cables while switching to our modern SP24-NS spark plug. Unlike generic adapters, this kit is specifically designed to work only with the SP24-NS plug. Other plugs will not seat or seal correctly and may cause misfires or poor performance.

Kit Includes:
1x PEET High-Temp Plastic Threaded Adapter (interfaces with SP24-NS and 24V military cable ends)
1x Brass Insert Plug (positions spark plug tip correctly and supports proper heat range and ignition performance)

Sold individually. SP24-NS spark plug sold separately.

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How It Works:

Military vehicles like the Dodge M37 and Jeep M38 use 24V shielded ignition cables that screw onto large military-style spark plugs (e.g., Autolite 2245 or 2243), which are becoming increasingly hard to find.

This adapter threads directly onto our SP24-NS spark plug (14mm x 1.25 thread), allowing it to interface with the original 5/8″-24 threaded cable ends. It preserves the waterproof and radio-suppressed design of your original 24V system.

Important Compatibility Note:
This adapter only works with our SP24-NS spark plug. Other 14mm plugs do not have the correct shoulder, reach, or sealing geometry and will cause performance issues.

Installation Instructions:

1. Use Only the SP24-NS Spark Plug This adapter is precision-designed to match the dimensions of the SP24-NS plug. Do not substitute.
2. Insert the Brass Plug Drop the included brass insert into the adapter.
3. Thread the Adapter Onto the Plug Carefully screw the adapter onto the SP24-NS spark plug until snug. Do not overtighten.
4. Install the Assembly in the Engine Thread the assembled unit into your cylinder head like a standard 14mm plug. Torque to spec: 1821 ft-lbs for aluminum heads, 2530 ft-lbs for iron heads.
5. Attach the Military Ignition Cable Thread the 24V waterproof cable end onto the external 5/8″-24 threads of the adapter to complete the sealed and shielded connection.

Compatible Vehicles:

• Dodge G740 / G741 Series (M37, M43, M601, etc.)
• Jeep M38, M38A1
• Other vintage military vehicles using 24V shielded ignition cables

Why Use This Kit?

• Retains your original 24V waterproof ignition system
• Eliminates the need to find rare 18mm military spark plugs
• Uses a currently available SP24-NS spark plug that fits, seals, and performs correctly
• Maintains proper compression, ignition timing, and waterproof shielding