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History of Cummins BigCam Engines


Some interesting facts and data about Cummins Big Cam engines.

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Questions about The Cummins Big-Cam engine

Is your Cummins a
big-cam or small-cam engine?
Click to find out

The Cummins Small-Cam engine's cam-boxes
Compare the size of the
Cummins Small-Cam engine's cam-boxes
to the size of the Big-Cam engine's cam-boxes
in the following image

What do the Big-Cam engine's
cam-boxes look like?
Click to see them

Cummins Big-Cam engine's cam-boxes
Compare the size
of Cummins Big-Cam engine's
cam-boxes to the size of
the Small-Cam engine's cam-boxes
in the previous image

What is
the most recognizable feature
of the Cummins
Big Cam I and Big Cam II engines?
Click to find out

Look at the cast-aluminum oil-pan!
The cast-aluminum oil-pan
of the Big-Cam I and Big-Cam II engines
was the replaced by
a pressed-steel oil pan
for the Big-Cam III engines

What does the name
Cummins N855 BigCam mean?
Click to find out

Meaning of the name N855 BigCam

Bore of BigCam engine = 5.5 inches
Stroke of BigCam engine = 6.0 inches
Therefore displacement of one cylinder =
pi * (radius squared) * stroke =
3.14 * 2.75 * 2.75 * 6 = 142.4775 Square inches
Therefore displacement of the engine =
142.4775 * 6 = 854.865 (rounded = 855) Square inches

N = N series engines
Includes N855 and N14 engines.

So we get the N855 BigCam engine
And also the N855 SmallCam engine

Cummins Big Cam I

Observe the Small - Cam Camboxes

Big Cam I Camboxes - highlighted

Small Cam and Big Cam I - same exhaust manifold

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

Cummins Big Cam II


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

Salient feature 1:
Big cam II still using the aluminum oil pan

Salient feature 2:
Pulse Manifold introduced with Big Cam II

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

Cummins Big Cam III


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
Salient feature:
Big Cam III engines - started using
the pressed steel oil pan

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

Cummins Big Cam IV


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.

Chinese Big Cam IV
note the new type pulse manifold

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

Big Cam IV engine

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