Has there ever been a 8–3 in the Primera Argentina?

Yes, 4 times.

The first time: April 26, 1908, Belgrano Athletic beat San Martín Athletic (Belgrano Athletic 8–3 San Martín Athletic).

The last time: December 6, 1972, San Lorenzo (Mar del Plata) beat Independiente (Trelew) (San Lorenzo (Mar del Plata) 8–3 Independiente (Trelew)), 53 years ago.

Home wins: 4. Away wins: 0.

Nearby scores

1. 9–2 5 times
2. 9–3 2 times
3. 9–4 Never
4. 8–2 16 times
5. 8–3 4 times
6. 8–4 2 times
7. 7–2 43 times
8. 7–3 22 times
9. 7–4 5 times

All games

1. December 6, 1972 San Lorenzo (Mar del Plata) 8–3 Independiente (Trelew)
2. November 15, 1970 Kimberley (Mar del Plata) 8–3 Talleres
3. May 30, 1940 Lanús 8–3 Estudiantes de La Plata
4. April 26, 1908 Belgrano Athletic 8–3 San Martín Athletic