Pulling V.A at idle

Timing at RPM

Example 1
Using a factory '73 318 distributor, timing at 1000 rpm is 9* BTDC, initial is zero.
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Example 2
Setting a factory '69 318 distributor so the engine had 18* BTDC at 1000 rpm, the initial is 11* BTDC. But we can't measure that until the engine is slowed to 700 rpm or less.
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Some examples of factory small block high performance timing curves in this post.
1968 340 timing
But bottom line is get the idle sorted out, then deal with any adjustments to the timing curve that may be needed.