Has there ever been a 7–4 in the Primera Argentina?

Yes, 5 times.

The first time: October 28, 1923, Argentino de Banfield beat Porteño (Porteño 4–7 Argentino de Banfield).

The last time: April 20, 1941, Platense beat Lanús (Lanús 4–7 Platense), 85 years ago.

Home wins: 3. Away wins: 2.

Nearby scores

1. 8–3 4 times
2. 8–4 2 times
3. 8–5 Never
4. 7–3 22 times
5. 7–4 5 times
6. 7–5 3 times
7. 6–3 58 times
8. 6–4 18 times
9. 6–5 4 times

All games

1. April 20, 1941 Lanús 4–7 Platense
2. June 19, 1938 Estudiantes de La Plata 7–4 Chacarita Juniors
3. September 27, 1931 Racing Club 7–4 Independiente
4. December 18, 1927 Independiente 7–4 Racing Club
5. October 28, 1923 Porteño 4–7 Argentino de Banfield