ok....

are you using anything like det cans to detect detonation or just adjusting by ear?

im confident but i also know when im swimming in deep water so excuse my cautious aproach. Right........

the vacume advance unit appears to screw into and out of the distibutor so i assume thats adjusting the pre-load on the vacume spring, also, how are you measuring the advance at higher RPM or are you just keeping it out of det? using a strobe gun?

thanks for your help

JOSH