Cummins Big Cam History

Big Cam I

The first Big Cam I engines were introduced in 1976.
Cummins aimed to meet new US government legislation at that time regarding noise levels and clean air requirements.

This engine replaced the Small Cam 855 series engines and it features a greater camshaft diameter and the introduction of top-stop injectors.

Visual differences

The major visual difference between small and big cam engines is that the cam boxes on the side of the engine were made much larger in big cam engines.

This feature made the big cam engines instantly distinguishable from small cam engines.

Refer to the preceding photos

Known Big Cam I CPL numbers

205 222 266 287 294 298 306 308 310 327 322 323 324 327 328 332 344 353 354 369 393 463 499 537 582 661

Big Cam II

Big Cam II engines were introduced in 1979.
The new features in this engine were:

• demand-flow cooling
  i.e. only cool when the engine demands it
  to use the saved horsepower for output work
• pulse exhaust manifold introduced
  A big increase in performance
  Some users upgraded their big cam I engines
  with pulse manifolds just to get this increased performance.
• T46 turbo chargers introduced

Known Big Cam II CPL numbers

329 330 338 339 345 349 377 391 392 414 433 449 450 454 455 456 457 458 459 473 481 482 483 485 491 492 506 509 516 518 529 536 543

Big Cam III
Big Cam III engines were introduced in 1983.
The new features in this engine were:

• New pressed steel oil pans
  - a very noticeable feature
• New oil cooler and water pump
• Top Stop injectors modified to DFF
  DFF - (Direct Fuel Feed),
  extra fuel flow assists cooling
• Holset HT3B turbocharger introduced

Known Big Cam III CPL numbers

530 531 553 554 558 578 579 581 585 586 588 606 611 612 614 615 616 617 625 632 634 635 650 653 654 657 677 702 743 744 757 789 891 988 989 1310 1411

Big Cam IV

Big Cam IV engines were introduced in 1985.
The new features in this engine were:

• New intercooler introduced
• Cross flow engines introduced
• Cylinder heads modified
  not interchangeable with earlier models
• Electronic Injection Begun
• Pulse manifolds improved

Some Big Cam IV's not Cross flow

However, it appears not all Big Cam IV engines had all the new features.
Some new engines coming out of China - are called Big Cam IV and they are not cross flow engines - they look more like Big Cam III engines, with the Big Cam III look intercooler, but they do have new-type pulse manifolds.

Known Big Cam IV CPL numbers
642 658 673 674 675 676 718 749 794 795 796 797 806 811 812 814 821 827 832 833 838 840 903 904 905 910 911 974 1185 1186 1187 1188 1210 1211 1352

 N855 Links:

•  Big Cam Specs
•  Small Cam Specs
•  Cummins engine specs