Due to the wrong valve guide and stem specification, it meant all the team's engines were suffering valve pick-up.
If not for the postponement of the first event in the Darwin double-header, Kelly Racing would likely have had only two days to travel to Hidden Valley and complete its two engine rebuilds.
Speaking with Speedcafe.com, Kelly said the team was prepared for the worst.
“Two pairs of heads just made the Supercars truck and they brought them over for us,” said Kelly.
“When we were stuck at the border for a while we actually grabbed those parts off Supercars.
“Based on whether we were going to be racing last weekend or not, we were prepared to start putting the engines in a car park there just in case, but we ended up not doing that.
“We would have had Thursday night and Friday night if we needed to get it done, which would have been okay,” Kelly added.
“Having the week this week to do it certainly is a bit more cruisy so we don't have to get permission to work through the night or anything.
“We're pretty much on schedule and hopefully have most of tomorrow off and Thursday off before we come back and get stuck back in if they fire up and run up okay.
“We'll come back and finish setting up the garage and we should be fine.”
With permission from Supercars, the team partially set up early at Hidden Valley Raceway on Monday.
The team will complete the rebuild on its spare engine later this week once parts arrive from the Gold Coast.
“There's a set of heads that are somewhere between here and the Gold Coast in transit that are getting delivered to the motel,” Kelly said.
“Once we get those we can build up a spare engine for the weekend.
“Everything is on track at the moment unless we find any issues once we fire them up, but we should be firing the first engine up at some point today. Hopefully it's all good.”
The team won't be able to dyno the engines before the fifth round of the Virgin Australia Supercars Championship.
“Just getting all the wiring and all the adapters to a dyno are quite specific to the engine.
“I don't think we'll be able to dyno an engine again until who knows when.”
“Hopefully that was 100 percent the issue,” Kelly said of the engine valve problem.
“We won't really know until we do a few k's on them, but that's certainly looking like that's what the problem was.”
The BetEasy Darwin SuperSprint is scheduled for August 15-16 at Hidden Valley Raceway.