(amazingly I was able to log in today...)
Ozzie,
I looked up the NGK-UR45GP you're using. Which is a Conical seat & .460" reach Chevy application plug.
https://www.ngk.com/product.aspx?zpid=10176
What heads are on your 302?
If they're Ford, AFR, Edelbrock you should install a SET of Autolite 3924 (they come pre-gapped at .044") Gasketed base and 3/4" reach.
https://www.summitracing.com/tx/part...SABEgKNv_D_BwE
Just to be safe on the plug reach (depth). A quick check take a 90deg scribe or a piece of wire and bend a short 90 bend at one end. Slide in the spark plug hole in the head until it reaches the inside and can be hooked.
Place your thumb at the opening of the spark plug hole on the scribe. Remove the scribe or wire and measure the distance from the tip of your thumb to 90 deg scribe or wire bend.
If its approx 3/4" the 3924 plugs are safe to use.
I really think you have a pi$$ poor ground at the plug base causing the connection at the plug top and plug wire to overheat at that connection point. Once it melts a hole in the boot it can jump to the nearest grounded metal object.
4Likes
Threaded Mode
