Daniels assessment if pretty well right on. Here's the longer version. With FoMoCo coming out with two brand new engine designs for the 1958 model lineups, the Y-Block family of engines was relegated to grocery getter status. The last thing needed in 1958 was for a Y to actually outperform any of the new engine offerings. As such, all performance options for the Y went to the wayside and this was done quickly by lowering the compression ratio, reducing the rocker arm ratio, smaller camshafts, and only offering two barrel carbs for most Y applications.

Lorena, Texas (South of Waco)

Since the Y-Block was de-tuned when the FE became the performance engine, I would assume reduced valve lift might improve economy & longevity in general (?).

6 VOLTS/POS. GRD. NW INDIANA

Does anyone have any thoughts on why FoMoCo opted to go back to the 1.43:1 rockerarm ratio after using 1.54:1 for 1956 and 1957?

Is there any valve train geometry issue (pushrod, rockerarm shaft, rockerarm, or valve stem location... or the angle of the valve in the cyl. head) that makes 1.43:1 better in reducing valve guide wear or some unwanted force factor?

Thanks for your input.

NoShortcuts
a.k.a. Charlie Brown
near Syracuse, New York