This is confusing. How can a plug be angled or straight. Aluminum heads require a plug with a washer not tapered. You better do some more research and get it right.
OH, L98 plugs are at an angle, tilted toward each other away from the exhaust ports, vs the old type heads where they aimed straight at the individual cylinder.....I forget just why, but flame propagation?? they claim a bit higher efficiency....
I had a set of iron heads, straight plugs, every thing was fine with two differant set of headers...they were 993? 933? castings....then went to Edel aluminum heads, straight plugs....still fine, but more clearance...go figger....
then I went with another set of headers, and SAME iron heads after a cyl head gasket blew....had nothing but problems with intermittant spark plug burning on # 5&6 cylinders...fine when cold, intermittant shorting when hot...go figger....drove me crazy...:crazy: so now I have #113 castings L98 aluminum heads on there, and they are angled in, and work fine, plenty of clearance...so much so I don't even need the Jabobs ceramic boots or short Accell plugs anymore....they don't fit anyway....