Hi guys.

I'm going to do a timing on the car, so I would like to know which cylinder number 1 is and where the mark is located to aim the strobe gun.
Thanks in advance.

Regards

 

Distributor rotor facing/pointing frontwards towards number 1 cylinder (@ TDC) you start your wires from the number 1 cylinder position going counterclockwise (1-8-4-3-6-5-7-2). Ensure you're following the 1971 GM Oldsmobile Chassis Service Manual (CSM) to establish proper dwell, timing & A/F mixture.

 

Timing tab indicator location

 

Three images I copied from images you previously uploaded to this site. Yellow arrows indicate general location of the timing mark tab/indicator (located on engine directly above slightly right of harmonic balancer).

 

Another image to provide additional clarity to which cylinder is the #1 cylinder.