Autolite 104 vs 764 plugs

[Sick Puppy]

Just curious what you guys prefer.
I've been using 104s (full thread) while 'the book' calls for 764s (half thread).

Here is what Autolite to say: http://www.autolite.com/media/11832/half_fullthread.pdf

[dagenham]

I don't see the need for the full thread design. These heads aren't like the Triton motors where they were blowing out. These are cast iron heads with. I've never heard of any problems with the plugs coming loose.
I would just get the half thread and not worry about it.

[dznj]

I thought I saw a note somewhere, that the half thread was made for the factory, and the full thread was equivalent. So, the half-thread are probably becoming scarce, and the full thread is equivalent. As long as the plug sits in the same spot in the chamber, all is well.

http://mx.autolite.framautogroup.com/sites/default/a/uploads/en/half_fullthread.pdf

D

[MikeFleming]

Full thread versus half thread makes no difference in the stock, iron head. as long as they're the same heat range, tip length, etc.

The threads provide the mounting/retaining capability, the tapered seat provides the sealing, temp transfer and positioning (depth control).