what's the application? Just wondering why you're not using it. On a race car it won't matter but street driven vehicles benfit from the vaccum advance. Part throttle driveability is way better with a properly adjusted vaccum advance. Fuel economy is better and I've found most engines run cooler with the added timing at part throttle.......hook it to ported vaccum and it will idle like it's not hooked up and it will have no affect on full throttle performance. I just made a believer out of some folks last week on a '67 mustang with a 428cj. Car has a msd distributor and the advance was plugged off. I hooked it up and driveability was night and day different. Felt like it was in a bind at cruise speed and built a lot of heat without it. You want the highest timing possible without detonation at cruise speed and an adjustable unit helps you get it just right. If it's a track car just unplug it.