[jwd]

There is NO reason NOT to run a vacuum advance on the street. Your engine will run cooler, have better throttle response and you'll get better gas mileage. It needs to be hooked up to constant vacuum. Get a vacuum unit that is rated at 2" vacuum less than what your engine idle vacuum is. You don't have to worry about detonation as your timing retards when any load is put on the engine. Mechanical advance only distributors on the street is another one of those "if it's good on the track, it must be good on the street" ideas that is completely wrong.