OK, so Im not new to working on engines, or cars/trucks... but how does leaning the air fuel mixture raise the vacuum? Also Ive checked the Krangen's and Auto Zones in my area and I cant find a simple vacuum gauge with the hose to connect to carb. All I can find are those vacuum gauge/ brake bleeders and those are kinda pricey. Ive used 'em a couple times for brakes but they keep braking on me and I dont want to spend that much just for a simple vacuum test gauge. BTW I'm trying to tune my Barry Grant Speed demon with 4 corner idle adjustment on my 383 with Comp Cams XE274 (230/236 duration @ .050). It seems to be running a little rich.