Originally Posted by F-2 Speedy (Post 4838385)

Pretty sure that SB said the long reach plug was correct for the 088 head

Originally Posted by resurrected (Post 4838389)

I run short AC's in my 088 heads.

Originally Posted by F-2 Speedy (Post 4838385)

Pretty sure that SB said the long reach plug was correct for the 088 head

Originally Posted by SB (Post 4837939)

That spark plug appears to have longer reach than what oe cast iron heads use. (.460”) What heads do you have ?

this is what they should look like with factory cast iron heads:

Originally Posted by SB (Post 4837947)

Okay. Oem GenV cast iron rectangular port heads. Should be using a typical .460” reach 14mm thread tapered seat plug.

Being supercharged, i’d run an acdelco mr42t or equivalent.

Possible that those extra long spark plugs you used caused preignition. You could have other tuning issues too, but this is a serious problem.

Originally Posted by Zole (Post 4838390)

What would that be in NGK world..thank you

Originally Posted by cheech (Post 4838395)

Standard and Iridium numbers below.
The actual plug number for each is in the comments.
NOTE: The numbers listed are the OEM heat range.
https://cimg7.ibsrv.net/gimg/www.off...5da738c3c8.png

Originally Posted by F-2 Speedy (Post 4838403)

did you previously say 180 comp on all cylinders now #6 is 120 ?..........Id run a heat range 7 in the NGK