Jamal claimed the Williams family bragging rights over brother Kai as Plymouth saw off Cheshire Jets on Sunday night.
It completed a perfect weekend for the Raiders, who also beat Sheffield on Saturday, and ensured they leapfrogged Leicester in to third place in the BBL.
The defeat for the Jets leaves their play-off hopes in the balance, although they do have two games in hand on those around them.
They now sit two wins from the top eight after both Guildford and Milton Keynes won on Sunday.
Guildford sent Glasgow crashing to their second narrow loss in as many nights (83-81), while the Lions dented the hopes of Mersey’s play-off hopes with a 81-78 win.
It leaves the Tigers level on points with Jets but having played two games more.