Chevy decided to overbore the blocks .030 resulting in a 402 motor beginning in 1970. As far as I know, there is no difference in casting numbers and I've never heard of a JC code. Of course, I am often wrong about this stuff...
Personally, I think they overbored to clean up castings that were not up to snuff or they had some other motivation having to do with spending less money...maybe they got a killer deal on 402 pistons or something. That is usually the kind of thing that motivated them. ----- Original Message ----- From: "Peter Hnat" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, December 19, 2005 2:12 PM Subject: [Chevelle-list] (no subject) Would like to know about 396 vs. 402 big block motors........why the jump to 402 cu. In. from 396 cu.in. and about when the change took place. I also have heard / read to tell the difference between the motors the 396 has a two letter code ( ie JC ) and the 402 has a three letter code ( ie CDE ) . Thanks, Pete Hnat '69 Chevelle SS
