I may or may not have a problem . The engine I purchased from Mattituck few years back when they were in operation recently was unpickled and started for the first time. After checking into gapping the plugs I noticed something that got my attention. The spark plug electrode seems to only extend about halfway into the spark plug hole and doesn't sit flush with the bottom of the hole like I think it really should. This is a lightspeed ignition that Mattituck installed to check on the new engine and ran it with these plugs that I received . My thinking is because the depth of the 18mm spark plug hole looks like it could be 13/16, they received 13/16 length plugs but by the time the 14mm adaptor was installed with only a 1/2" helicoil, the plug only reaches halfway into plug hole. According to what I read this can be a point of carbon buildup and potential predetonation problems? See photos to clarify what I'm saying. I emailed Klaus at LSE the photos and he says I have the right plugs and adaptors. I'm not confidently sure.