The web site of Museum Victoria lists the mint for Sarawak copper coins between 1870 and 1889 as Smith and Wright, Birmingham which is not supported by other sources.
The weight was 144 grains in the measurement units of the time, equal to 9.33 g.
References to additional information:
[Book] Atkins, James. 1889. The Coins and Tokens of the Possessions and Colonies of the British Empire. pp 228-229
[Book] Saran, Singh. The Encyclopaedia of the Coins of Malaysia, Singapore and Brunei, 1400-1967. Kuala Lumpur, Malaysia: Malaysia Numismatic Society, 1986. pp 351-372.
[Book] Kavanagh, Kevin F. 1969. The Coins of Malaysia, pp 65-73
[Book] Remick, Jerome. 1971. British Commonwealth Coins., pp 489-492