I just completed the overhaul of an Ansonia iron cased mantel clock (my job no. 4422). It has the common 4 pillar 8 day time and strike movement of dimensions 5 x 3-1/4 inches. In this clock, a previous repairer had replaced the srike mainspring with one that is 3/4 inches wide and .018 inches thick. The time spring was an original that is .0153 inches thick.
When assembling the movement, I put the original thin mainspring in the striking side, and for the time mainspring used a spring 3/4 inches wide x .0138 inches thick by 120 inches long (no. 77.303 from R & M Imports). This spring gives a good pendulum motion of just over twice the escape arc. It will run the clock reliably without causing excessive wear.
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