I rebuilt my 223 about a year ago and was using the stock distributor and stock holley 1904 carb, I also had switched it to 12 volt using a GM alternator, It ran great and idled smoothly but I was thinking it would be nice to get rid of the points and get mechanical advance along with the new distributor and maybe a hotter spark (I had already put an HEI in a jeep 226 with very good results) so I installed a new Duraspark distributor for a Ford 300 and an Accel super coil thinking this would be a slick set-up. Well it does run fine but I have to advance the timing to 16-18 degrees to get a halfway decent idle, it seems to run fine but I'm surprized I can't get a nice smooth idle out of it. It idles a little rough at 5-600 rpm which is a little higher than factory settings anyway. I wonder what I'm missing? new plug wires and all new parts just not as smooth as the old set-up. any ideas? Anyone have firsthand experiance they would share? Thanks guys.