77 timing mark?

[1987ss]

trying to time a 1977 305.. and when you look with light the timing mark is at 12 oclock position on harmonic balancer when you retard timing so mark comes closer to timing scale car stalls out.. is the distributer off a tooth or two? any help is GREAT!! we tried moving wires over 1 on cap in eithor direction and it didnt help..

[hotrod_chevyz]

1: Disconnect the power to the dist.
2: Pull spark plug #1.
3: Have a second person sit in the drivers seat, and tap the ignition switch in very short intervals as you hold your finger snug over the spark plug hole, until your finger is forced off the plug hole by the pressure from the piston coming back up.
4: Check the timing marks. If its close to 0, line it up by hand until the marks line up perfect. If you cant see the mark repeat step 3 until you have the lines within 20 degrees or so from the mark, before you line it up by hand.
5: Stick a screwdriver down the plug hole to make sure the piston is at its highest point.
6: Pull the dist. cap and see if its pointing to what your calling number 1. If its not adjust and correct it until the rotor is pointed at number 1
7: reinstall the dist cap and plug 1. Fire it up with the vac advance disconnected, and time it to specs.