Tonca was born on 2 May 1947 in
Bucharest, Romania and initially practiced
boxing before switching to football with
Steaua București's junior squads. In 1966 he joined
Jiul Petroșani, making his
Divizia A debut on 12 November 1966 under coach
Ștefan Coidum in a 1–0 loss to
Dinamo București. After playing in his first seasons at Jiul as a right or left defender, Tonca started to play alongside
Andrei Stocker in the central defense. He would approach them, cautioning against overly ambitious play to avoid severe tackles, explaining his imperative to win for his four children and the victory money essential for their provision. Tonca eventually won the competition two years later after a 4–2 victory against
Politehnica Timișoara in the
1974 final, as coach
Traian Ivănescu used him the full 90 minutes, helping Jiul win its first trophy. Afterwards he played in both legs and scored one goal against
Dundee United in the first round of the
1974–75 European Cup Winners' Cup which was lost with 3–2 on aggregate. In May 1975, during a Jiul –
Politehnica Iași home game, the wooden stand of the
stadium started to burn due to a cigarette thrown into the pile of seed husks. Afterwards he moved to
Minerul Lupeni in
Divizia B where he ended his playing career. ==Managerial career==