Matthew McCallum wrote:

Flash Volume 9 (Flash 171-180; June 1967 to August 1969; 240 pages)


  
The cut-off point would be Flash 179 "Flash - Fact or Fiction", which was the first Cary Bates (and Earth Prime) issue. Flash 180 launched a major stylistic change with Frank Robbins taking over as writer, and 180-181 was the first Flash two parter - the absolutely dreadful "Flash in Japan" story. Frank Robbins had many high points in his career - both story and art - but it is hard to argue that this is one, and the racial stereotyping found here is very jarring to modern sensibilities.