Revised Valve Spring & New Rotator for 2005-14 Cummins 8.3 & 8.9L,
QSB & QSL Engines
As a product improvement, the use of rotators on the exhaust valves for QSC and QSL engines with the Cummins Common Rail Fuel System (CM850) and rated more than 298 HP was implemented. The start date was September 29, 2005 on engine serial number (ESN) first 46535055.
Because of the increased thickness of the valve rotator as compared to the valve spring retainer, a shorter exhaust valve spring is required when exhaust valve rotator, Part Number 3979599 is used.
Two valve springs that are compatible with the valve rotators are also identifiable by the color markings shown in the chart below:
Exhaust Valve Spring / Color
3999907 / Two vertical yellow stripes
4931931 / Fully coated white
Valve Spring Specifications
Spring # Free Length Assembled Load Valve Open Load
PN 3999907 2.185” (55.5mm) 105-114 lbs (489+/-20 N) 214-239 lbs (1009+/-55 N)
PN 4931931 2.102” (53.4mm) 87-96 lbs (409+/-20 N) 203-222 lbs (948+/-42 N)
The previous valve spring Part Number 3944711, and colored with two vertical purple stripes) and valve spring retainer, Part Number 3944452, will continue to be used on the intake valve s in the QSC and QSL.
CM850 Cummins Common Rail Fuel System Engines
Component ISC/ISL QSC/QSL less than 298 hp QSC/QSL greater than 298 hp
Valve spring, Intake 3944711 3944711 3944711
Valve Spring, Exhaust 3944711 3944711 3999907/4931931
Valve Spring Retainer 3944452 3944452 3944452, Intake only
Valve Rotator, Exhaust N/A N/A 3979599
Valve spring Part Numbers, 3999907 and 4931931, can both be used on the same cylinder head but not within the same cylinder.