That darn petcock! During one of my hard starting days, I took apart the petcock because I was only getting a trickle of fuel.  I have an inline fuel filter and could see that it was almost dry.  I wasn't very familiar with the inner workings of the petcock but switched settings and noted the feeble (to me) movement by the little lever inside.  I managed to misplace the spring when I put it back together apparently over riding the vacuum function.  Last friday, I had to stop when it ran dry.  I moved the valve through the stops and got nada, then pulled the vacuum line loose and puffed in and out on it, still just a trickle, I pulled the gas hose loose from the carb and got a few drops going, then a steady trickle.  I had about 1.5 gallons in it, so it shoulda been decent fuel pressure, at least enough to fill up the filter.  I did make it home, but it is disconcerting to see a mostly dry filter.
Has anyone done anything else other than the manual conversion?