Why are you attempting to adjust the timming under 10 degrees BTDC? Is that a spec you read in a book. Are you sure what the initial advance is on your dizzy? There are several different advance cams that may be installed in your dizzy. You need to confirm, either by direct observation or by total advance adjustment. If you carefully unscrew and lift the breaker plate and look at the advance cam below, You'll see a number stamped on the flat area before the slots. Typically a 9.5 or and 11 sometimes a 7.5 and as high as 15. This number indicates the total dizzy advance. To get total advance, you mulitply that number by for example 9.5 X 2 is 19. Now, on pump gas, and 8.5 CR and stock cam, You do not want to exeed 35 degrees total advance. So, 35 -19 = 16 So the optimal timing for this dizzy is 14 ~ 16 BTDC. If it was an 11 dizzy, optimal would be lower, 11 ~ 13. In reverse, if it was a 7.5 unit, 7.5 X 2 = 15, 35 -15 = 20 so 18~20 would be the range. If you car sound "Super Retarded" at 10, It just very well might be.