OK, thanks for the info. I have a Ryobi block and piston that I aquired that has two intake ports on each side, and a more oval exhaust port ( no brace in the middle). It is twin ring, but according to Frank Bowman, maybe a single ring is better. At any rate, I will be playing around with this arraingment. I have a degree wheel and will see if there is any difference in port timing and head space. At any rate, as soon as my new Bowman ring arrives, I will be checking things out and keep the info flowing.
Another question I have. Does MTD own both RYOBI and Homelite?