RE: 21cc Echo timing?
Set it between 26 and 28,no higher than 28.Use a 15x8APC for best tresults.At least thats what mine liked.I sold one of my other ones but heres a pic of one im doing now.This one has the domed piston,not flat.Dont know if it will be better or not.Im making a header for it,ive already made a mouse can tuned pipe.