This is an extra large bushing. If your spark plug repair bushing blew out, you can probably use my other, lower cost bushing for your repair. Check my other listing. This one is for extreme blow-out or if the hole blew crooked and made your plug hole egg shaped.
This bushing is made out of a Grade-2 Mild Steel bolt. This bushing can be used as a last resort option instead of replacing your cylinder head on Ford Modular engines. Drill and tap your spark plug hole to 7/8-9, using a 49/64" drill, and use your spark plug to screw in this adapter. Use jb-weld on the external threads of this adapter. Wait 24 hrs for jb-weld to setup, before starting your engine.
This bushing will NOT screw all the way thru and fall into the cylinder.
External thread is 7/8-9 Internal is 14mm x 1.25 pitch (same as factory spark plug thread) Overall length is about 7/8". A sheet of suggestions for installation is included.