I have a Zc block with the D16y8 head are the 3 marks on the damper to set dizzy timing the same as a reg. D16y8 . I just installed a new dizzy set timing to the middle mark of the 3 marks on the damper it starts and runs fine but now when i let of the gas while driving i get gargling out the exhaust like if am running rich. Is there a difference on the marks of the damper?