there are a couple P51 with gas engines, one is a sig 300xs, my yaks and sbachs all have cowl rings which I really like. The sig had an open cowl but has been enclosed as the engine is inverted an cooling is down below and can't reach to the top any more. I am try the flexible CA and rubber washers- see how that works out. I want to thank all for the input and will let you know if I find a great way to fix this simple but annoying problem.