...cfg/sourcemod/sourcemod.cfg
Code:
// Specifies the amount of time that is allowed between chat messages. This
// includes the say and say_team commands. If a client sends a message faster
// than this time, they receive a flood token. When the client has accumulated
// 3 or more tokens, a warning message is shown instead of the chat message.
// --
// Requires: antiflood.smx
// Default: 0.75
sm_flood_time 0.75
*edit
Ok.. have to read harder.
Check is plugin running on your server,
rcon sm plugins list
And look cvar current value,
rcon sm_flood_time
You could try increase that value more to see results.
Look sourcemod logs is there any errors