While blueprinting the engine, the team for the 14D car found a faulty valve, so a new cylinder head sourced from a Holden dealer. The replacement head had larger valves than the original, after checking with Holden, it was indeed the correct part for the engine. 14D was the fastest Monaro and lead most of the 1968 Bathurst. Lap scoring confusion gave McPhees 13D the checkered flag, with the 14D being recorded as finishing second.

Later the scrutineers found the inlet valves were not identical to the 327 specifications and the car was disqualified. A protest commenced on the grounds that the valves were the only ones available from Holden. The team was cleared of any wrong doing, but the disqualification remained.