3X spark plugs

ironmountain · Feb 3, 2023

Hi, does anyone know what the thread size is on the brass top of an original 3X plug?

Thanks Richard

Ray in La Mesa · Feb 3, 2023

7/8 x 18

alexiskai · Feb 3, 2023

7/8 is the bottom thread, he means the top where the connector attaches. For some reason I feel like it’s metric, but I can’t find the number.

Bob C · Feb 3, 2023

Some plugs are 4mm and some are 8-32.
I checked a reproduction 3X and it is 8-32.

Y-Blockhead · Feb 3, 2023

Bob C is correct. Champion 8/32. Autolite and Motorcraft are metric 4x7mm.

Synchro909 · Feb 3, 2023

Y-Blockhead said:
Bob C is correct. Champion 8/32. Autolite and Motorcraft are metric 4x7mm.

That would be 4 x 0.7mm.

Y-Blockhead · Feb 3, 2023

Synchro909 said:
That would be 4 x 0.7mm.

Thanks Synchro, that little dot makes a big difference.

mcgarrett · Feb 3, 2023

If you're needing a source for replacements, check page 3 of the attached catalog link:

https://restorationstuff.com/

Y-Blockhead · Feb 3, 2023

mcgarrett said:
If you're needing a source for replacements, check page 3 of the attached catalog link:

https://restorationstuff.com/

You can get them at a good hardware store that sells table lamp parts much cheaper. Snyder's has the also, both inch and metric.