Formula S . Now you have me wondering . I ran with the Promax plates jetted like i said in my post . What would the symptoms be if they are not covering properly like you said . i did not use the thin plates under them. I am in the process of changing engines now to a 340 stroked to 418 . I planned to go to a 3310 750 holley on an LD340 manifold. I have felt like the 6 pack would be hard to tune with the big motor, and have intended to sell it . I may consider running it though, and some insight on what I should be doing with the jetting.