Well, sometimes it's not the gas or the timing or the carb idle adjustments, but the engine components. Joe blow wants to have a 532 HP engine. He reads all the literature and determined he needs an X camshaft and a B intake manifold and a F carb to get the 532HP. After all if the magazine says they can do this for $534 in parts then 'why can't I?' After boring the cylinders and buying the hot pistons, intake manifold, carb, cam, and heads he has an engine that gets 532 hp on the dyno. Man is he happy! Then he puts it in his Pontiac and it runs like crap, stinks like hell and gets 4 miles per gallon. All the drilling of holes in the carb plates and timing adjustments in the world do nothing to stop the smell. WTF? He has an intake manifold that is rated from 2000 rpm to 7000 rpm a camshaft that comes online at 3300 RPM, and a carb that will support a 1127 CID tractor puller. Joe drives the car to the local A&W at 34MPH. Everyone around him puts on safety glasses and a respirator. Joe can't figure out why, after all he got all the latest RACE parts. I have a friend who suffered with stinky exhaust for ages, but for some reason wouldn't entertain the thought it may br the parts not the adjustment that was the problem.
I'm sorry, was I ranting?
Manifold vacuum is the vacuum below the throttle plates, the vacuum reading one has whether the throttle is open or closed. Ported or timed vacuum is just above the throttle plate, none until the throttle is opened. No, or little, vacuum sense at idle and total vacuum sense with the throttle open. We adjust idle mixture with the throttle closed so we need to have the guage connected to manifold vacuum.
