I went and looked at a 72 cutlass convertible unfortunately in the dark. that aside the engine code is 396921 and the heads had a large C on them. Owner says it is a 455. Does this decode out as a 455


Thanks

 

The block number checks out to be a 455. The "C" on the heads doesn't, though - they check out to be for the 400 engine 67-69. It could be what you really saw was a "G" or a "big captial G little captial A" which would be 445 heads for 71 and 72, respectively.

Randy C.

 

"C" heads were used on ALL the run of the mill BB's 1967 thru 1969.

Only 68-9 W30 400 and most 455 '68 H/O's and all 455 '69 H/O's got the other available letter those years- "D"

Agreed that the '71 should have G heads, which resembles a "C" in the dark. To help verify, look for the 6-digit [3 and 3 on each side] adjacent to the center lower rocker cover bolt.
C- 394548
G- 409100

The 396021 block is a 455 anywhere from '68 to '76.

 

As Chris correctly points out, the C heads were used on 455s for the 1968-69 model years. Check the VIN derivative stamp on the block, but if the heads are original to the block, this is a 68-69 455.