A former kickboxer,[2] Sim Ngam won the 1984 ACBS Asian Snooker Championship with an 8–5 defeat of Vichien Sangthong in the final.

[1] In his next tournament, the 1985 Grand Prix, he recorded 5–3 wins over both Derek Mienie and Fred Davis to reach the third qualifying round, where he was eliminated 1–5 by Eugene Hughes.

He also reached the third qualifying round of the 1985 UK Championship, losing 4–9 to Joe Johnson after defeating Roger Bales and Mick Fisher.

[6] In the qualifying rounds for the 1986 World Snooker Championship, Sim Ngam whitewashed Bernard Bennett 10–0 before losing in the deciding frame to Paul Medati, 9–10.

[1] He won the amateur 1995 IBSF World Snooker Championship, defeating David Lilley 11–7 after trailing 5–7 at the end of the first day of the final.