<VV> Correct timing on 65 140 motor with 68 #371 distributor???

[John Gull]

I am having troubles achieving optimal timing on my 65 140 motor . I replaced a very sloppy 330 distributor with a double bushed 68 140 distributor #371. According to charts for distributors they are totally different initial timing settings. I am set at 18 degrees at idle and runs good in low rpm but not in higher rpms. Any suggestions would be appreciated. John Gull in Asheville NC