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Does changing Dwell effect mileage? 140-160

"Anyhow, since dwell is defined as the number of degrees rotation that the primary coil is charging, a larger dwell will give more charge. So you are suggesting a dwell of 60 will give a better spark than a dwell of 50. Resulting in, presumably, better mileage?"

Yes to all that, Trev. With the emphasis on "presumably", which seems reasonable.

Where you say, I can't argue with what your hardware showed you. But I still stand by my theoretical numbers.

Going back to your original post, with 60° dwell and timing set to 10° before top center, the points would close at 70° BTDC (close at 70°, open at 10° = 60° Dwell).

If you adjust/shrink dwell to read 50°, my assumption is that 5° is lost at each end of the dwell period. So the points will close 5° later and open 5° earlier than with the 60° dwell. The 5° earlier (firing time) would now be 15°BTDC, or 5° advanced from what it was.

In any case, I think the 60° dwell for a 4 cylinder motor has sort of been proven to be the optimum for the basic points system. Shorter dwell reduces spark. and longer dwell probably risks overheating the Primary coil, which typically runs warm anyhow, as I seem to recall from way back when.
--
Bruce Young
'93 940-NA (current), 240s (one V8), 140s, 122s, since '63.






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