Hi Matt,
Having also used the Lockwood Carb Synchronization Kit, I have a suggestion that may save you some effort in diagnosing your idle problem. First, you should verify that the Lockwood gauges are reading the same value when equal vacuum is applied.
I had a similar issue as you are having. After carefully doing the mechanical sync, I then connected the recently purchased pneumatic gauges. I found that the readings were quite different, so I readjusted the throttle cables. The idle then became very rough. Since it was idling smoothly before I did the pneumatic sync, I suspected the gauges. I connected a "u" shaped piece of vinyl tubing to the gauges, then punched a small hole in the middle. Sucking on the hole caused an equal vacuum on both gauges. I immediately saw that the indications were not the same, so I recorded the differentials on a correction card. Now, redoing the pneumatic sync placed the throttle cables very close to where they were with the mechanical sync. And, best of all, the engine now runs very smoothly.
I hope this helps.
Peter
