Looking for a little advice on the timing numbers I just pulled from my 73’ Duster (backfire issue)
Zero degrees at idle was for the smog distributor curve.
lets looks at the '73 shop manual and see how your two measurements compare with the timing for a '73 318 (2 bbl of course)
That looks like this when usin g TDC at 750 rpm. If the engine was set at 2.5BTDC at 750, then shift everything up 2.5 degrees.
Lets add your measurements to the graph.
Sure looks like that distributor does not have the original advance curve.
I would try 5* at 750 rpm, then get a few more timing measurements.
Early 318s used 5* initial, so that's certainly safe.
With the 4 bbl, it should be Ok with more advance early as illustrated by the 273 4bbl timing limit
Good start. Having the rpms with the timing is very helpful.
Zero degrees at idle was for the smog distributor curve.
lets looks at the '73 shop manual and see how your two measurements compare with the timing for a '73 318 (2 bbl of course)
That looks like this when usin g TDC at 750 rpm. If the engine was set at 2.5BTDC at 750, then shift everything up 2.5 degrees.
Lets add your measurements to the graph.
Sure looks like that distributor does not have the original advance curve.
I would try 5* at 750 rpm, then get a few more timing measurements.
Early 318s used 5* initial, so that's certainly safe.
With the 4 bbl, it should be Ok with more advance early as illustrated by the 273 4bbl timing limit