The LA stations were faster at adding top hits.
Looking over the KRLA and KFW
B-each-Boys charts, I see on KRLA's chart,
Good Vibrations peaked at No. 1 faster than nationally and listed it as its No. 1 for a couple of weeks, A MONTH before it hit No. 1 on Billboard.
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Same with KHJ.
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Interestingly, on
KFW-Beach Boys' chart, the great song (arguably the greatest song of the 60s), didn't hit No. 1.
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Keep in mind that with the arrival of KHJ on the scene and its almost immediate impact on the ratings at the time, the other LA top 40 stations were trying to figure out ways to best the newcomer. KBLA tried to out-KHJ KHJ--they hired Humble Harv away from KHJ (briefly) before he returned to the KHJ fold. IF KBLA had had better reception outside of the San Fernando Valley, they might have pulled it off.
Initially, KRLA took other routes. Starting in the summer of 1966 and lasting most of the rest of that year, KRLA became an "all-request all of the time" radio station (there's a great aircheck of Dave Hull doing this format on both the old and new Reelradio sites as well as elsewhere on August 1, 1966). In 1967, KRLA tried to win fans back by trying to play hipper (i.e. more hard rock) than KHJ (there is a great display of this format with Casey Kasem from June 1967 on the start date of the Monterey Pop Festival.) At one time, KRLA even went to an automated top-40 format during late 1968 and early 1969. KRLA ultimately had its best success against KHJ when Johnnie Darren was program director between 1970 and 1971.
In fact, Johnnie was so successful that he was fired for that success. At the time, it was owned by the same non-profit organization that owned KAET Channel 28 (one of Los Angeles' two PBS affiliates) and the rumor was that Board members were jockeying to buy the station but they didn't want to pay the higher cost if it had beatedn KHJ in the ratings.
Ultimately, Art LaBoe (with some assistance from comedian Bob Hope) wound up purchasing the station. And, because of the late Mr. LaBoe's support of Los Angeles' black and Hispanic communities, KRLA became a much more rhythmic-leaning top 40 with a lot of oldies on the playlist than it had been in the past and that allowed it ultimately to outlast KHJ.
KFWB continued to do what it had been doing, and, as Michael Hagerty has already noted, completely floundered as a top-40 station as a result.
Anyway, this is primarily why the weekly charts, especially those at KRLA, were so different in late 1966.