Points Gap: .014-.016 (26-28 degrees dwell) Plug gap .035 Auto-lite BF42 plugs
Get a chiltons repair manual from the library for your car.
Spark plug gap - .034" Point Gap- .021 M/T, .017 A/T Dwell Angle- 24 to 39 M/T. 26 to 31 A/T If the 390 was produced in 1962, the ignition timing was five degrees before top dead center ("BTDC"). If produced in 1963 and equipped with a manual transmission, the ignition timing was five degrees BTDC, and eight degrees BTDC if equipped with the automatic transmission. If produced between 1964 and 1966 and equipped with the manual transmission, the ignition timing was four degrees BTDC, and six degrees if equipped with the automatic transmission. If the 390 was produced in 1967 and not equipped with the Thermactor Exhaust Emission Control System, the ignition timing was 10 degrees BTDC. The ignition timing for all other 390s was six degrees BTDC.
Info at this site might be helpful. http://www.justanswer.com/questions/2zzo6-timing-a-1966-pontiac-gto-389-with-tri-power-what-is-the-best
what is the timing degree for a 1966 gmc 292v6
The timing mark on the top gear should be at 06:00, while the timing mark on the bottom gear should be at 12:00. IOW, they "point to each other" Good luck!
( 6 ) degrees BTDC for the manual transmission ( 12 ) degrees BTDC for the automatic transmission
The 1966 Chevy Impala ignition switch can be removed by loosening the retaining ring at the top of the ignition switch. Remove the wiring harness. Reverse the process to install the new ignition switch.
Check for fuel (bad fuel pump or clogged fuel filter) Check for spark (bad or weak ignition coil)
Stock is .35 but since you have aftermarket ignition I assume coil is hotter as well so i would open them up to .45. Use copper core since they are more conductive and spark easier and perhaps index as well. You should consider getting the old factory "fuelie" heads and ram's horn ex manifolds.
There were not any timing belts in 1966. The timing should be set at 4 degrees before top dead center. With the base timing, the centrifical and vacuum advance all together should be 35 degrees.
what is initial timing on 1966 chevy 250
Dwell 28-32 degrees Spark plug .035