All the talk about the RB's using the Rb 6 glow plug, or using hotter plugs is kinda funny, 10 or so years ago, racing in 'California, with the RB S7 Europa, standard plug, turbo plugs at that time were only used on the on road engines, and if you were running RB's, you were using an Rb 8 plug, and that was all everyone used on RB engines, then you had to be on tune, or you were not racing. I had met Steve O'donnell soon after, and I ask why we did not use a hotter plug, his answer was, people that use hot plugs can't tune. This was the Nova Rossi based engines, not other engines he was speaking of.