San Fran has seen two iterations of the Shamrocks franchise. The first was an entrant into the PCHL from 1944 through 1950, which was an amateur circuit on the west coast. The Shamrocks played six seasons in the league with middling success. They have an over .500 record in two of six years, and lost in the first round of the playoffs each of those years. A few Shamrocks had a cup of coffee in the pros, the most notable being Wally Hergesheimer who played six seasons in New York. This version of the Shamrocks would go bust after the 1949-50 season.
The Shamrock moniker was revived in the late 1970s, during a tumultuous period in hockey history. With the WHA, NAHL, and SHL all folding around 1977, the PHL was started to fill the gaps in the west coast hockey market and pulled in former WHA teams like the Mariners and Roadrunners. The Shamrocks were revived as part of a a four-team league and played at the Cow Palace. They faired well, going 24-17-1 in 42 games in 1977-78, which is a whole lot of games for only having three other opponents. The Shamrocks would sweep the Roadrunners in three games, capturing the only PHL title. The following season, the Shamrocks would go bust in the middle of the season with only 4 wins in 23 games and the PHL would follow suit shortly after.