Originally Posted by twiscomb

I have a low mileage, 71 LT1 with original Holley List 4801 and the correct vacuum advance unit. Last year, I took some time and tested a few timing settings with a vacuum gauge and an Innova digital timing light. I first tested the overall driving condition with a "total timing" setting at 36-38*. After driving around for a few months, I reset the "total timing" to 34* total advance and I think 34* setting is the best setting so far. At 36-38*, I noticed the starter had to work harder to get things going and my idle speed was less consistent. At 34* the starter turns easier and idle consistency was very good (the engine idles well now at just 800 rpm).

At 34* total timing, I had 14* advance with vacuum advance plugged and 28* advance @900 idle idle with vacuum advance connected. Also, my total advance did not stabilize until I had the engine rpm between 2500 and 3000 rpm. My engine operating temperature is normal to low at this setting. A big "thank you" to Lars for providing so much helpful information to help me understand the value of optimizing engine timing.

Tom