I'm new to tuning with vacuum advance and I have a few questions. I shortened my mechanical advance slots to .375. I set my initial to 16 (vacuum unplugged) and get a total of 32 ( vacuum unplugged). When I connect the vacuum advance my initial goes to about 20 and my total goes to about 40. I haven't driven it yet but it idles pretty good with the vacuum unplugged and idles like crap with the vacuum plugged in. Does anybody have any info to post that would help me or feel like taking the time to walk me thru this ?