Ok everybody; I want to run a little hotter spark plug in my rampside (80 HP manual trans) than the Bosch 4214 (regular) or 7502 (silver). Old Bosch # is W8AC. According to the Corvair Basics book, I should be looking for Bosch W10AC. What is the current Bosch equivalent? Thanks, Scott Wilson '63 Rampside '63 Monza Convt.