MTFCA Forum

Has anyone ever used aluminum foil around the sparkplug to tighten loose threads in an aluminum head. I think one of the plug hole threads in my aluminum high comp head are getting worn. I don't like the way it feels when I tighten the plug.

Is it a 14mm thread, or 1/2" pipe thread?

The plugs are 1/2 NPT

The problem is easily solved by using adapters for modern plugs. Screw the adapter in once only, with the sealant of your choice, and then use modern plugs. You may not like the look though.

Allan from down under.

1/2” npt Helicoil is available. I have the kit and have probably fixed at least a dozen over the years!

When putting plugs in an aluminum head, Anti seize compound should be used to protect the head threads from galling.
Try some & see if the plug doesn't go in to far before tight. If you are not familiar with it, its basically aluminum powder & oil made into a paste.

Plug adapters are an option. I still put anti seize on the adapters.

Hi Will,
If you don't like the looks of the modern plugs & adapters they can be made from the later crimp style 1/2" npt plugs so they look like 1/2" plugs Craig.

Thank you everyone.

I have used aluminum foil in a steel head. The threads had gotten rusty and when I tightened the plugs some of the compression would cause oil bubbles to come up around the plugs. The aluminum foil seemed to seal them just fine.
Norm