Celebrating 4/29 with Cadillac’s Smoothest Sixties Big Block

After a month spent discussing raucous big blocks and their exploits on banked ovals and quarter-mile drag strips, we’re ready for something a little more mellow. Something smooth. Today is 4/29, but we’re not going to spill any more ink on oft-celebrated baddies like FoMoCo’s Boss ‘Nine engine or the Super Cobra Jet Lima—today, we’re talking about the Cadillac 429, found under the hood of every car that rolled out of their Clark Street plant between 1964 and 1967.

The silky 429ci stump-puller was the immediate descendant of the 390 that had been introduced in 1963, not to be confused with the older 390 used from 1959-1962 (itself the ultimate expression of the 331ci mill that introduced the OHV V8 to American buyers). The 429 was another 90-degree …