[68 P.O.S.]

Working Longhorn & Mike C have it dead on. To put it mildly, the guy who said not to hook it up is a friggin' moron lol. You need the added advance the vac can provides during idle and cruise for improved cooling, mpg, throttle response, and driveability. Make sure you hook it up to manifold vacuum so it will work as originally designed. It doesn't need more than 15 degrees like stock or you'll get detonation. Get the Crane 99601-1. It's the best, most adjustable vac advance on the market. Plus it comes with the correct advance springs for your dizzy's mechanical advance to put in the right rpm range (use 1 blue and 1 silver).