OK, I did a search and couldn't find anything specific about this. Here's a shot of the 1955 shop manual:



Great! So how do I tell if a rocker tower is upside down relative to the others? Only 20 thou difference... I don't have a depth gauge!



Anybody ever seen this before? I've never seen a warning from any of the y-block gurus about this, no "common mistakes" in assembling y-blocks... getting the rocker shaft upside down and having oiling issues, yes.... having towers mixed up and down, and cracking a shaft... no.



So, I gotta ask... is this for real? If so, is it '55 only?



I was careful to keep the lock washer marks on the towers on the same side when I rebuilt the rocker assemblies. At this point, I just figured that side had to be the top, and went ahead and re-installed them that way. I figured 90% chance that the engine will be ok.