Originally Posted by Lee446
Not to hijack, but in this application are there any equivalents that use a 5/8" hex plug for header flange clearance?


Not that I am aware of.

1974 474 Duster - in a similar engine I use NGK 3332. Also known as XR5.
I have never fouled a plug. I think it would idle until it ran out of gas. Lol.
Of coarse Your results may vary depending on state of tune.
Hint - with that cam it will like 18-20 deg advance at idle.

Last edited by GomangoCuda; 12/12/19 08:39 PM.
In theory, there is no difference between theory and practice. In practice, there is.