That casting number is for a 230 or 250 cubic inch Chevy or Oldsmobile inline six. The difference in the displacement will be determined by the crankshaft stroke- - -both engines have a 3 7/8" bore size.

castingnumbers.info/site/detail/18266/3921968

Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!