Spalding recorded a vital victory on Saturday to stay above the relegation zone.
Speedy wingers Gav Sharman (2) and Ashton Capes scored tries at Memorial Field.
Spalding were up and running directly from the kick-off, giving no room to Rolls Royce.
They had a surprise for the visitors with the return of Capes and Sharman.
They soon illustrated the threat as Capes burst down the right wing and round the last tackler to score near the corner for an unconverted try after five minutes.
Encouraged by the early score, Spalding started to dominate territory and the visitors infringed at the breakdown but two penalties were missed.
Every time Spalding managed to get the ball out wide, scoring opportunities were being created.
Capes thought he had scored again with another excellent run and, as the defence closed, he kicked ahead to the dead ball area.
Capes and a defender touched down at the same time and the referee awarded a drop out. Capes was again denied minutes later.
Rolls Royce started to kick for territory and finally exerted sustained pressure with a succession of scrums as they edged their way towards the Spalding try line.
The visitors were encamped on the five-metre line and with their superior scrum, a try looked certain. But a knock-on at the base allowed Spalding to escape.
Unsurprisingly, the second half followed a similar pattern but this time it was left-winger Sharman, on his return from a hamstring injury, outpacing
the Rolls Royce defence to score by the posts.
Willis Ingleby converted and a 12-point gap had been opened up within two minutes of the restart.
Jason Steels, playing behind a retreating scrum, secured possession on the retreat and always got across the gain line with his runs to set up the next phase as he laid the ball back.
Not far behind was Kieran Bailey in the back row as he came into his own in the second half, showing ability in the lineout and making tackles on the blind side.
Spalding’s forwards put in an immense performance around the field to deny Rolls Royce in open play.
Also high up on the tackle count was fly-half Dan Adams but it was his strong running from deep inside his own half that helped to seal the home victory.
He evaded several tackles as he burst from the 22 straight down the middle of the pitch. With cover defence closing in, Adams offloaded to Sharman who was running in support and his pace took him clear under the posts for a converted try with only eight minutes remaining.
Rolls Royce’s forwards were not going to be denied as they set up one last attack through their superior scrum.
They were awarded a penalty try as Spalding were being driven backwards and collapsed under pressure.