OTC Tools OTC 5607 Compression Tester Ford Adapter. Use with OTC compression testers (or other compression testers with a 14mm thread) to access hard to reach spark plug holes. Features and Benefits: Works on 2004 and newer Ford 4.6 and 5.4L, 3 valve Triton TM V-8 engines. Easy-to-turn feature makes starting thread fast. .