The rule of thumb is that you need at least 15 inches of engine vacuum to operate a power brake booster safely. With a heads-up driver and some caution you might run some boosters with even less ...
There’s an old expression, “Why stop when you’re having fun,” but when the subject is a 1969 SS396 El Camino that couldn’t stop to save its proverbial soul there wasn’t anything fun about it. Such was ...