SMALL BLOCK I.D.

[Dave the Wave]

all the numbers are off the boss in front of #2 cylinder, so i take it, it must have been decked. or it`s a 307 or something. my good friend was told it is a 350. well, we got it out of the `55 yesterday. best i could do it the casting number back by the dist. 3970010. how can i decode this? thanx!

[BamaNomad]

An '010' block was first cast in mid-1969. Usages of the block were in '(late) 1969 302 engines for Z28, and 350/350 engines for Corvettes and (later on) other 350 ci engines for trucks, and other Chevys. All of them were machined for 4-inch bore, and many were 4-bolt mains, but I understand they also machined them for 2-bolt caps in later years. Get the date from the opposite side of the back and that might tell you a little more. If the engine was swapped as a unit, perhaps the cast numbers/dates from the heads and intake will also give you clues as to the engine's origin.

PS. If you can get a very high resolution of the machined pad, or use a magnifying glass to discern the machine marks it could tell you if it was machined in the factory (longitudinal linear broach marks), or a swirl machine cut on a mill in a later machine shop (ie. the block was later decked). They did sell these blocks 'across the counter' for many years, so it's possible that it has factory 'broach marks' without an assembly stamping.

[Dave the Wave]

thanx bama. the heads are double humps. perfectly good shape, they`ll be for sale