Is there any one here that knows the difference in the mechanical advance curve in these dist. between the units for a automatic trans and a manual. I know the automatic trans. unit is stamped # 9 and has stiffer springs than the manual stamped #8.5 . I am wondering at what RPM either is going to full advance, and when the vacume advance and the cintrifical starts on each. I have been running a '79 manual model for about 3 yrs on my L-24 , but now I am installing a slightly built 280 and I would like more info. in this area, thanks for any information and or direction as to where I can find it . Gary:classic:

Gary, This page will give you all the specs

dizzy specs

But I would suggest the 8.5 (17 degrees at the crank) over the 9 (18 crank) as it will give you a touch more initial advance.

Victor , thanks. This is exactly what I was looking for . This a real interesting page , I took a look around on it and recommend it to all. I especially liked the dyno info. Thanks Gary:classic: