which grade fuel

I can't believe you asked for this, PoisonDart74. To retard the timing on the LA V-8, loosen the screw at the base of the distributor and rotate the distributor in a counter clockwise direction.

On a more serious note, the Clean Air Package tune-up specs set the timing at 5º ATDC in contrast to the more normal 10º BTDC for the other 49 states.