421 Super Duty 1963

[Rickandboys]

Just aquired a 421 SD Pontiac Block, matching Crank, Rods w/ pistons, rebuildable. Anyone know of a site to run numbers on old Pontiac Blocks? I'm sure it is one of the nascar superduty limited production engines from 1962 or 1963.

[BIG-L]

Pontiac blocks are easy to identify if you know what to look for. It is simple, for example, to visually categorize all 1959-and-later blocks into 389/400 or non-389/400. All displacements other than 389/400 possess a "transfer lug" (found at the rear of the block shaped like a "mountian" or "pyramid"). There are only two exceptions: the 1961-62 421 SD (the same blank casting as the 389) and the 1973 SD-455. All V8 blocks cast prior to 1959 (287, 316, 347, and 370) were "standard" displacement and did not have a transfer lug. In addition, these 1955-58 blocks did not use side-mounted motor mounts as did all blocks from 1959 forward. All blocks through model year 1963 have a production number cast into the passenger side of the block. The casting number for these blocks are as follows:

1955 (287 c.i.d.) #518037
1956 (316 c.i.d.) #521560
1957 (347 c.i.d.) #523293
1958 (370 c.i.d.) #528456
1959 (389 c.i.d.) #532000
1960 (389 c.i.d.) #536387
1961 (389 c.i.d.) #538181
1961 (421 SD) #538181
1962 (389 c.i.d.) #538181
1962 (421 SD) #538181
1963 (326 c.i.d.) #548211
1963 (389 c.i.d.) #543680
1963 (421 c.i.d.) #544988

[Rickandboys]

Thank You for the info. I did not know about the pyramid thing. I did find what i really have- YK, B-Body, 1965, 421, 376HP, Turbo 400, 4 Bolt Main, 3x2 BBL, High Output. Block code 9778791 (YK stamped on front), Last digit by distributer-hole is a "4". Motor mounts have two bolt-holes and two freeze-plugs ob each side. Thanks for new info. Regards, Rick