Quote:
Originally Posted by AdamIsAdam
Very interesting. I'll hook up a gauge. I will say this, when I was using a different vacuum can that wasn't fully engaging at highway speed, that's when I was getting the "trailer hitch" surging, which went away when I changed to this can.
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I tune power valves on occasion driving with a vacuum gauge. It's interesting how quickly it will move when throttle is moved quickly, and how easy it is to dip into the power valve circuit.
Also interesting how we loose 3-4 inches of vacuum up here at 5,000 ft vs sea level. Makes PV tuning fun. Sometimes you tune it up here and then end up with a part throttle stumble down at sea level because you aren't getting into the PV circuit soon enough anymore.
Haven't had too much issue with vacuum advance really. Only really noticeable on the cans that have a wide timing/vacuum range. When running manifold vacuum on those cans, adding 3-4 inches of vacuum when driving down to sea level kicks up the idle a couple hundred rpm. On cans I run with a shorter range where they are all done at say 8 inches of vacuum, it tends to not be a problem because it's already running max vacuum advance most all the time, even up here at 5,000 ft.