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Machining a '66 Bonneville head to accept '69 push rod tubes.



One of the problems with using an earlier head on a later engine is that the pushrod tube sockets are not deep enough. In order to use the head as is one would have to replace the pushrod tubes and the cam follower blocks as well. Then, the gaskets/"O"rings that are appropriate for the earlier head would be used as well. Anyone working on the engine at a later date with out being privy to this fact would truly be hatin' life before that was resolved. In addition, all these parts are not really what I would call cheap. So, the decision was made to modify the earlier head to duplicate the socket depth of the '69.


But, with out any specifications to go from I would have to transfer all the dimensions. The first thing that I noticed when I get the head chucked up on the mill was that the pushrods, and, of necessity, the sockets were angled slightly. To duplicate that angle I turned a piece of round stock so that it was a snug fit in the socket and would bear on the shoulder of the socket.




This would allow me to "index" off that round to get the head of the mill properly aligned.





The angle is approximately 4 degrees. They were cut to the same depth as the '69 head. Fortunately, there is a built in chamfer so there should be no problem inserting the pushrod tube and "O" ring.






Now I should be able to use all the standard components and any one coming after me will never know the difference.