Can't find that casting number - but it could be either a 307 or a 350.
A list of small block casting numbers can be found here: http://www.nastyz28.com/sbchevy/sblock.php
39700XX is almost at the bottom of the list.
The casting number 3970044 refers to a Chevrolet small-block engine block produced in 1969. It typically has a displacement of 350 cubic inches (5.7 liters) and is commonly found in various Chevrolet vehicles from that era. The block is often associated with high-performance applications due to its robust design.
what does the casting number GM 3892657 say about this engine block
What Chevy engine block has the castin I mean casting number 397004
that would be the casting number of a Chevy 350
The casting number will tell you what block it is, but in some cases the block will be more than one displacement. IE 302, 327, 350ci on the same casting number (chevy)
check the engine block casting number
A small or big block Chevy have a casting number on the top of the block behind the driver side head. MorTec has Chevy casting numbers listed online.
350 cu/in block used in GM Goodwrench Crate Motor. Made in Mexico.
Try mortec.com.
this was done during the initial casting of the block and heads. it tells you what car it was on and size of motors and the size of cc the head is. some block casting and not very correct. i have a bbc 396 that has acasting of " hi perf pass truck" there is no such thing. just " hi perf pass", or" truck". head casting a alot more accurate tho. hope this helps.
What year and size engine has casting number B1378704E
chevy 350