Why the overbore from 396 to 402

[Kurt S]

JoeC got it right. It was emission rules related.

The GM literature (parts books, manuals, etc) got real confusing, calling the BB a 400 alot of the time.

I assume the new block handled the .030 overbore.
Interestingly, the late 69 blocks did not use the 70 3 digit code format, but the late 69 axles did.

[Mr70]

The three letter suffix began on the new 402 CID blocks.
Their cylinders were overbored by .032.
Example:
Code JH is 396.
Code CJH is 402.(or 400 as Kurt mentioned)
I have seen late built 1969 Chevelles with the three letter suffix block.

Kurt S
You say no 1969 Camaros have been found with the three letter suffix,even thought the 1969 Camaro model was carried over late into the 1970 model run.
I would have thought those later built Camaros recieved a three letter suffix,as the Chevelles did.
Anyone know why they didn't?

[Kurt S]

[ QUOTE ]
I would have thought those later built Camaros recieved a three letter suffix,as the Chevelles did.
Anyone know why they didn't?

[/ QUOTE ]

I'd guess cause it was a model year extension and they chose not to change the codes midyear (though it's not really changing them, just adding a digit...).
I've heard of 2 Camaro blocks with the 3 letter code, never seen them.