4C 71.07 is a high-redshift blazar whose optical radiation is dominated by quasar-like nuclear emission .
We here present the results of a spectroscopic monitoring of the source to study its unbeamed properties .
We obtained 24 optical spectra at the Nordic Optical Telescope ( NOT ) and William Herschel Telescope ( WHT ) and 3 near-infrared spectra at the Telescopio Nazionale Galileo ( TNG ) .
They show no evidence of narrow emission lines .
The estimate of the systemic redshift from the \ion H \beta and \ion H \alpha broad emission lines leads to z _ { sys } = 2.2130 \pm 0.0004 .
Notwithstanding the nearly face-on orientation of the accretion disc , the high-ionization emission lines present large broadening as well as noticeable blueshifts , which increase with the ionizing energy of the corresponding species .
This is a clear indication of strong ionized outflows .
Line broadening and blueshift appear correlated .
We applied scaling relationships to estimate the mass of the supermassive black hole from the Balmer and \ion CIV lines , taking into account the prescriptions to correct for outflow .
They give M _ { BH } \sim 2 \times 10 ^ { 9 } M _ { \odot } .
We derived an Eddington luminosity L _ { Edd } \sim 2.5 \times 10 ^ { 47 } erg s ^ { -1 } \sim L _ { disc } , and a broad line region luminosity of L _ { BLR } \sim 1.5 \times 10 ^ { 46 } erg s ^ { -1 } .
The line fluxes do not show significant variability in time .
In particular , there is no line reaction to the jet flaring activity detected in 2015 October–November .
This implies that the jet gives no contribution to the photoionization of the broad line region in the considered period .