Re: [AMC-list] First year for AMC bridged rockers?

[Frank Swygert <farna@xxxxxxxxxxx>]

Date: Sun, 27 Jan 2013 14:30:30 -0600
From: "Eddie Stakes"<eddiestakes@xxxxxxxxxxxxxxxxxxxx>

A customer asked me what year did AMC start using bridged rockers. I could
not give him a window. Always though 74 but know that these first appeared
in 1973, just not sure how early. A 401V8 I have out of a 73 AMX has a valve
cover tag of 612Z05 which is December 5th, 1973 401. The heads are casting
3220602 E and have bridged rockers, the flexplate is dated 7 73 (July 1973)
and engine never been apart. Waterpump 3215719 1 never replaced so as I look
at this, I am trying to establish a timeline, or window as to when AMC first
started using bridged rockers on AMC heads. This is earlier than I thought.
Ideas?
================================================

1973 model year it is! All the 1973 model year engines should have bridged rockers, which means they should have started engine production around August 1972.

In 1974 the six at least went back to shaft rockers for most of the model year. There was a patent dispute filed by Buick over the bridged rockers. The 74 TSM shows shaft rockers for the six, but still shows bridged for the V-8. Might be a slight difference in the bridge design, might just be an editing error in the TSM. I don't know for sure if early 74 V-8s went back to single stud rockers or not, maybe one of the V-8 guys will know. I can tell you that the shaft rockers were dropped late in the 74 model year and they went back to bridged before the model year was up, but I don't know for sure when. For 1975 everything was back to bridged rockers as the patent dispute was resolved. I have no idea how -- can't say if AMC just won, paid Buick, or there was some other agreement (maybe a patent license swap -- that's happened before -- Buick may have got permission to use something AMC had patented in exchange).

--
Frank Swygert
Editor - American Motors Cars Magazine
www.amc-mag.com


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