We recommend .0015" of clearance between the apex seal and the rotor slot for all applications, boosted or naturally aspirated.3 mm 13B Goopy Apex Seals are .115" thick, and you should be able to slide a .0015" feeler gauge into the rotor apex slot with a new apex seal.Our 2 mm apex seals are .075" thick and you should be able to slide a .0015" feeler gauge into the rotor apex slot with a new apex seal in place. Goopy Performance 13B 2 mm oversized apex seals measure .078" (+/- .001"). If your rotor slot measures .079 - .080", then you may benefit from our oversized 2 mm seals which will allow you to re-gain the .0015 suggested clearance.If your gap with the seal in place measures .002-.005" it is still usable, but keep in mind that tighter clearances means greater sealing characteristics.Take note that 13B 3 mm apex seal slots suffer the most when it comes to rotor slots over-tolerance. We have measured many used rotor slots and have found very few that still had the stock widths.
