Callaway Competition USA will miss the upcoming Pirelli World Challenge round at Long Beach and the subsequent events at Virginia International Raceway and Canadian Tire Motorsport Park, citing parts supply issues and scheduling difficulties.

The ADAC GT Masters championship-winning team and constructor is in its first year of PWC competition with the Corvette C7 GT3-R, which made its North American competition debut at the Grand Prix of St. Petersburg in March.

According to team principal Reeves Callaway, a shortage in the LS9-based engine blocks that are at the heart of the Callaway Corvette’s power plant, coupled with the beginning of the GT Masters season in Europe, have prompted the team to put its North American program on hold until the race at Lime Rock Park in late May.

“We have two contributing factors to our absence at Long Beach,” Callaway told Sportscar365. “We are in the process of shifting our engines to a new engine block part number.

“Our homologation was based on an LS engine block part from 2013, and that supply has been exhausted. The replacement engine blocks have just become available and are currently in testing.

“Second, we have a race date conflict with the start of season in Europe for the ADAC GT Masters.

“We have elected to transfer [driver] Daniel Keilwitz from the U.S. operation to the European operation where he can best help us defend the championship. The existing engines will be reserved for the start of GT Masters season.”

Callaway said the plan is to have the newly-homologated engine ready to contest the PWC races at Lime Rock, Road America, and Watkins Glen with Keilwitz as the driver.

The team initially announced a pair of the GT3-spec Corvettes for Keilwitz and American Michael Cooper but scaled back to a single entry just before the opening round.

Keilwitz claimed fourth and second-place finishes in his first two PWC starts but was forced to miss the Saturday race at Circuit of The Americas due to an engine problem that required the team to purchase a new block and rebuild the power plant overnight.

Keilwitz and co-driver Eric Curran were classified 19th in Race 2 at COTA on Sunday, after the car ran out of fuel.