Their reasoning was a “non-standard” induction system: 1/4'’ longer studs in the sump with a 3/8” aluminum spacer instead of the stock ¼ phenolic thermal spacer that normally goes between the throttle body servo and sump. In the Glasair, we put a big 90 degree stainless elbow to reposition the servo to allow room for the retracting nose gear. This does not meet Lycoming’s specifications hence “experimental”. I have asked that they be specific in the wording to state what the non-conformance is rather than leaving open ended as written. All other engine parts, both internal and external are per Lycoming specifications.