We have several NT855 engines and I am having to work on them all more and more. I have the Shop Manual for "Big Cam IV,New Big Cam IV and 88 Big Cam IV, NT855 series engines." Three of our engines are Big Cam IV's and the other two are Big Cam II's. My question is; In the manual the adjustments for the overhead are INT: .011, EX: .023 and injectors 5 to 6 ft. lbs. It makes sense that they are all the same, but just wondering if I should try to find a different manual for the II's. I know there are some good old Cummins guys on here that will know. Thanks in advance, Trav
The 5 to 6 ft lbs sounds a bit out as this detail is usually in Inch pounds and with close targets, is your torque wrench not in inch pound scale, although I still do plenty of the over head set work on Cummins motors I always reference the engine data plate and the Service book, this past Sunday I did the over head set on a VT555 (triple Nickel)fitted in a Versatile Tractor, For the U.K. now that is not a common engine or a common tractor, the injectors had 60 inch lbs (I know 5 ft lbs) as the target to set them at, if you set them to tight on 14 ltr engines it makes the engine hard to start, if they are set to light they black smoke so the target on the torque set needs to be on a tight tolerance, unless you are talking of the little T handle pre set 5 to 6 inch lb tool?? a few more verbs on your set method might be needed as 60 inch lbs is way off 72 inch lbs (5 to 6 Ft lbs) on a fine set detail as this?? I hope you can understand my script. tctractors
I know I always had the best luck when doing settings on engines without the "Top Stop" injectors was to use the dial indicator method to set the injector travel. Note that this requires setting the valves and injectors at a different position than if using the older torque wrench method. Sorry to say I don't think I brought home any Cummins manuals home when I retired and would not want to try to say how either is done without the book in front of me. Not positive but the settings may be different for the small cam and the big cam engines. One thing I liked about the injector travel method is it allowed you to see how close they were before setting them. If way off might lean towards replacing injectors due to carboned up tips, or give you a reason to pull push rods to inspect for loose tips causing excessive clearance.
Any fixed time 855 is 6 in lbs or finger tight (can still roll the little plunger rod with your finger) If it has STC/step time you use a the higher in. lb dependant on the cpl. Step time also requires you set the valves and injectors on the same cyl at the same time.
Hold up... Fixed time inj and valve on same cyl. STC inj. 1 valve 5 etc etc etc. Too many engines and too many overheads in my head.
I have used all methods to set injector travel on Cummins motors, the dial method is to slow for me although it is probably the best, the Cummins dealership (Now Closed) that I used for parts etc only ever used the Torque set method for this detail, I did ask the lads in the workshop about this detail, they all said the dial method was to much trouble unless the engine was under a Fuel usage investigation, this being caused by a complaint on heavy fuel MPG with a Truck. tctractors
My bad, inch lbs. I do not know why I put foot lbs. Thanks for the info.