I know I am driving you guys crazy and I am trully sorry but I did not get a clear answer yesterday on setting my timing. Totally restored 1970 440-6 rebuilt by a pro with 175 miles on it. When I set the timing to 10 degrees BTDC the car tends to run labored and backfires once in a while. Yesterday I put a vacuum gauge on the intake and it read 14 and was at the bottom of the late ign. timing area so I moved the dist. until I got up to 18 and in the green normal area and the car ran perfect so I got out the timing light and low and behold I had moved the mark on the balancer 20 degees. It was now 10 degrees oppisite. What is wrong here? I id this with the vacuum advance hooked up, is that wrong? Is there anything wrong with setting an engine with a vacuum gauge and forget the timing light. If it starts easy, does not ping thigs should be fine or am I missing something.