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Buick Big Block Casting Numbers, 400, 430, 455

Block Cast # Year Displacement
1231738 70-71
455
1238861 70-71
455
1241735 72-76
455
1242694 70-76
455
1381624 67
400
1381625 67
430
1383424 68-69
430
1383434 68-69
430
1383790 68-69
400
1384790 67-69
400
1393444 68-69
400
9773524 67-69
400
 
Head Cast # Year Displacement
1231109 67-69
400/430/455
Int 176cc Ex 134cc
1231786 67-69
400/430/455
1233472 67-72
400/430
1237661 70-71
455
1238142 72-76
455
1238148 72-76
455
1238529 70-76
455
1238530 70-76
455
1240149 70-71
455
1240150 70-71
455
1241449 72
455
1241786 70-76
455
1241860 72-76
455
Int 176cc Ex 134cc
1242445 72-76
455
1242455 72
455
1246322 72-76
455
1248922 72-76
455
1372963* 67-69
400/430
1377979 67-69
400/430/455
1377980* 67
400
1382091 67-79
400/430/455
1382983* 67-69
400/430
Int 206cc Ex. 142cc
1382985* 67-69
400/430
1382986 67
430
1384720* 67-79
400/430/455
1385649 68-69
400
   * Big Port

1967-70 heads are 69cc, closed chamber.
1971-74 heads are 71cc, closed chamber.
1975-76 heads are 76cc, open chamber.

In 1975 General Motors painted all engines corperate blue. A blue 455 is generally considered a more desirable motor to build.
Intake Manifold
Cast #
Year Displacement
1231718 70
455 4bbl
1236403 71
455 4bbl
1239925 72-73
455 4bbl
1243020 72-73
455 4bbl
1244302 74
455 2bbl
1245059 72-74
455 4bbl
1245375 72-73
455 4bbl
1247330 75
455 4bbl
1299925 72
455 4bbl
1374062 67
400/430 4bbl
1376998 67
400/430 4bbl
1382720 67
400/430 4bbl
1383438 68
400/430 4bbl
1386003 69
400/430 4bbl
1386681 68
400/430 4bbl
 
Exhaust Manifold
Casting # Part # Year Displacement
  1377139left 67
400/430
  1376998right 67
400/430
  1245433 left 67
400/430
  1238094 right
67
400/430
  1245443 left 69
400/430
  1238094 right 69
400/430
1233451left   70
455
  1238094 right 70
455
  1238094 right 71-74
455
  1233451 left 71-74
455
  123right -
455
  1233899left
455
  1243457left
455
  1246669left
455
  1246671left
455
  1383549left 70
455
  1246715 left 75
455
  1238094 right 75
455
  1384089 left 68
400/430
  1383648 right 68-70
400/430
 
Stage I Casting Numbers
Head Cast # Year Displacement
1240150 1970
455
1240146 1971
455
1238530 1972
455
1242002 1973-74
455
The story behind these four numbers is in question!

A letter or number after the casting number as in 1165165 X or -3 may indicate a change in update in the casting. This would mean a higher letter would be a later production.

A letter or number after the casting number as in 1165165 X or -3 may indicate a change in update in the casting. This would mean a higher letter would be a later production.