Timing on a 5.9 Magnum

Lelo Dart said
What timing is everybody running on there carbed Magnum engines?
Right now I've got it dialed back to 15 initial and 28 total and vac advance 10 degrees at full advance. Using the stock springs for a slow mech advance and it's still rattling occasionally while at cruise.

19-20 initial, 34 total mechanical and 52 all in with vacuum advance at full.
Iron heads, stock pistons 9.1:1 and 87 fuel at 5,500 elevation with normal heat range plugs.
Did you think about plugs yet?
They can cause pre ignition and engine run on when shutting down.