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Shielded Spark Plug Adapter Kit (2243 Spark Plug Adaptor 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.
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:
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Use Only the SP24-NS Spark Plug – This adapter is precision-designed to match the dimensions of the SP24-NS plug. Do not substitute.
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Insert the Brass Plug – Drop the included brass insert into the adapter.
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Thread the Adapter Onto the Plug – Carefully screw the adapter onto the SP24-NS spark plug until snug. Do not overtighten.
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Install the Assembly in the Engine – Thread the assembled unit into your cylinder head like a standard 14mm plug. Torque to spec: 18–21 ft-lbs for aluminum heads, 25–30 ft-lbs for iron heads.
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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
