Orrock has contested the opening four events of the season with the JamSport Racing outfit.
Three heavy accidents in as many events blighted Orrock’s start to his maiden UK Clio Cup campaign although last time at Oulton he came away with two points-scoring results.
The 26-year-old commented: “I’m parting on good terms with JamSport and wish to thank them for everything to date, but now I see this as a totally fresh start heading to the next rounds at Croft.
“Pyro obviously have won many titles before and are currently performing at the front with them and Mike Bushell leading the drivers’ and teams’ standings so who better to learn from?
“All I want is progress and, for me, progress at Croft would be getting inside the top ten for the first time and feeling like we are getting somewhere.
“I’ve not raced there before but all the circuits after that I’ve competed at so would hope to see more progress being made at those, but I’m under no illusions.”