can you tell me how hot of plugs i can run without hurting motor? I have a rod with 302,327,or 350 in it,according to the block #'s.194 heads.when I got it it had autolite ap26 plugs in it.seem to run fine but swithed over to a set of accel shorties to get some header clearance on wires.shorties only come in one heat range ,I think about 2 steps colder than the ap26's.went up to kansas over the weekend for show & cruise and wound up changing plugs in the parking lot with barrowed tools.not a fun job on this ride.only had about 400/500 miles on the shorties and they craped out.now I think I need to go back to ap26 or hotter but dont want to hurt anything.