I don’t know what you mean by “run good”. I don’t know what you mean by run good that’s a hard question to quantify. When I tuned it, I didn’t look at my timing light at all. I timed it based on what sounded good and smooth and what gave me the highest vacuum. Will it run at 24° yes. Does it seem to run better at 42° I believe so. I believe an engine is more efficient when you have higher vacuum. So I think I answered this question correctly or is best I could.