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8970 855 cummins overhead set
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coastalBend
Posted 6/22/2018 06:28 (#6827147)
Subject: 8970 855 cummins overhead set


south texas
A fellow member asked me about setting inj so i looked up some info on quickseve bc im getting old tired and forgetting things.

They changed the manual a year or 2 ago on quickseve for my engine. Now its called an N14 mechanical. The old book they listed had the valves at something like 11& 23 ( i can't remember the exact numbers, they are written on engine and my old book), now the n 14 book says 14 & 27. I know its only .003 or so different but its different. Anyone care to comment on these settings?

What valve settings would be best?

. Fresh engine, less than 200hrs. I used my old settings bc they were there and i didn't bother looking it up.

esn 30354056

cpl 1594



(B83C68A9-8112-46DB-B771-F33B31D437B8.jpeg)



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Attachments B83C68A9-8112-46DB-B771-F33B31D437B8.jpeg (97KB - 404 downloads)
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raider2b
Posted 6/22/2018 06:52 (#6827177 - in reply to #6827147)
Subject: RE: 8970 855 cummins overhead set


North Dakota
.011 and .023 are used when using inner base circle to set the injectors, .014 and .027 are used when using outer base circle to set injectors. Inner base uses a dial indicator to set the injectors and outer base uses a torque wrench.

This is a short mostly true description but there are a number of different descriptions depending on which injectors are used. I almost always use the outer base and torque the injectors, some are 72 inch lbs others are 115 inch lbs.
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hillfarmer
Posted 6/22/2018 10:56 (#6827604 - in reply to #6827177)
Subject: RE: 8970 855 cummins overhead set



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Helland
Posted 6/22/2018 12:20 (#6827729 - in reply to #6827604)
Subject: RE: 8970 855 cummins overhead set


SE ND
.
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dvswia
Posted 6/22/2018 13:58 (#6827825 - in reply to #6827147)
Subject: RE: 8970 855 cummins overhead set


sw corner ia.
I don't know what injectors your motor has but if it has top stops intakes should be 11 and exhaust should be 23. injectors are 6 inch pounds which is about a quarter of a turn( past zero lash).

standard injectors (earlier) are 14 intakes and 27 for exhausts, 72 inch pounds for injectors (some go 80 for injectors so yours may be different than this, get your cpl code and talk to cummins to be sure).

just did mine a couple months ago in my shop and the data plate on the left front on the accessory drive cover should tell you.

do you know how to sequence the valves by rotating the motor over while watching the pointer also on the left front? kind of a pain to jump down and rotate with a wrench but doable..

in case you don't it is:

Cummins N855
Timing Mark on A
When Valves on #5 are closed
Set Valves #5
Set Injector #3

Timing Mark on A
When Valves on #2 are closed
Set Valves #2
Set Injector #4



Cummins N855
Timing Mark on B
When Valves on #3 are closed
Set Valves #3
Set Injector #6

Timing Mark on B
When Valves on #4 are closed
Set Valves #4
Set Injector #1



Cummins N855
Timing Mark on C
When Valves on #6 are closed
Set Valves #6
Set Injector #2

Timing Mark on C
When Valves on #1 are closed
Set Valves #1
Set Injector #5




Edited by dvswia 6/22/2018 14:03
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blowsand
Posted 6/22/2018 13:59 (#6827827 - in reply to #6827177)
Subject: RE: 8970 855 cummins overhead set


mercer county, il
my pump and injector guy told me that even with top stops to use the OBC and Torque the injectors at the bottom of their travel. as if someone sets the injector travel itself wrong (cheap reman injectors most likely), the feeler gauge method could leave them too loose (not enough fuel being injected), or too tight (stuck injectors).
we have been doing it this way for quite a while now, and have had no problems. gotta plug Dave Lukken diesel here I guess.
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coastalBend
Posted 6/22/2018 14:01 (#6827829 - in reply to #6827177)
Subject: RE: 8970 855 cummins overhead set


south texas
So during the obc method, your claiming the cam/push rods are at the lowest piont and during ibc method they are slightly elevated. I am a novice at the 855 but it seems that the obc method has the inj set when the cam is pushing on inj, valves completely closed. While the ibc method has the piston in the same position but ur setting the lash on a different inj with 0 load on that inj.

maybe i misunderstood but i don't see how there are 2 different settings for valves if they are completely closed.

i have no questions about setting the inj, just about why the lash on valves is different than my tag.

im looking for tag pic.

the stc inj take 125 in lbs
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coastalBend
Posted 6/22/2018 14:05 (#6827836 - in reply to #6827825)
Subject: RE: 8970 855 cummins overhead set


south texas
It has top stop stc inj. The engine tag did say 11 & 23.

i don't have questions about the procedure, just why quickseve gives me different information than what the tag on motor does. Quick serve specifically lists the stc inj at 14 & 27. This motor is real goofy. Cummins gives the same info as quickseve. Ive already been down that road.

your method is the ibc. Ive been using it but all new literature says the obc method is better. U have to have a special tool for the stc inj.

Edited by coastalBend 6/22/2018 14:07
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dvswia
Posted 6/22/2018 14:08 (#6827840 - in reply to #6827829)
Subject: RE: 8970 855 cummins overhead set


sw corner ia.
ok.. you should talk to cummins or a mechanic who knows what injectors you have, because 125 inch pounds is not going to work with the top stop, so you may have the standard injectors..

I do not know why there are differnt settings, I just go by what the plate cpl tells me to do. I will say that mine had about a hundred thousand miles on it and not one valve was over .002 out of adjustment. since you have a new rebuild it would be a good thing to run the overhead as you intend.
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dvswia
Posted 6/22/2018 14:12 (#6827847 - in reply to #6827836)
Subject: RE: 8970 855 cummins overhead set


sw corner ia.
I have not heard of top stop injectors that were set to more than six (yes, 6) inch pounds. if I was going to run them down to 125 I would have to know for sure this is correct.

I also did not know you cold substitute ibc for obc method. yes, the motor they sold to deere for ag use is for sure different than automotive.

edit again: I wonder if the ag use motor just runs at a higher temperature throughout the motor since it is going to run at a constant load that they want a little more cold valve clearance?

Edited by dvswia 6/22/2018 14:16
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dvswia
Posted 6/22/2018 14:19 (#6827856 - in reply to #6827836)
Subject: I just saw you picture in the OP


sw corner ia.
that plate clearly states injector torque at 5-6 inch pounds. not 125.. did you see that? it also says valve lash is 11 and 23... these are your commandments!
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coastalBend
Posted 6/22/2018 14:20 (#6827857 - in reply to #6827840)
Subject: RE: 8970 855 cummins overhead set


south texas
The inj i have are not in question. They are stc inj.

Its why when i put my esn into any cummins system, i get incorrect information. The tag says 11 and 23.
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coastalBend
Posted 6/22/2018 14:24 (#6827865 - in reply to #6827847)
Subject: RE: 8970 855 cummins overhead set


south texas
At 6in lbs u are setting the inj with 0 load on the rocker, basically just taking the lash out of the system. Ibc method

at 125inlb u are setting the inj with the cam pushing on the inj to fire or loaded up in some way, im not sure on that. Obc method

in ibc u set the inj on different cylinder than valve, obc u do the same inj and valve. Im thinking when u set with obc, each cylinder is at tdc or just before when inj fires and both valves are closed
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coastalBend
Posted 6/22/2018 14:25 (#6827868 - in reply to #6827856)
Subject: RE: I just saw you picture in the OP


south texas
Yes, thats for the ibc method.

U can do both but they are different methods. Cummins put out a flyer with my last set of inj to use the obc method. I didn't have the 125inlb wrench so i did ibc.

u also have to have the stc tappet holding tool to do the settings on ibc for this motor.

Edited by coastalBend 6/22/2018 14:26
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dvswia
Posted 6/22/2018 15:35 (#6827936 - in reply to #6827865)
Subject: RE: 8970 855 cummins overhead set


sw corner ia.
to get 6inch pounds loosen jam nut while holding adjuster, then turn by hand till you feel zero lash. now turn till you get the 6 in pound torque, which is really light, about a quarter of a turn, and you can almost do it with finger pressure. this worked for me.
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blowsand
Posted 6/22/2018 17:53 (#6828101 - in reply to #6827868)
Subject: RE: I just saw you picture in the OP


mercer county, il
nope, when the tag says TS zero, that means you have top stop injectors.

Anymore, most accessory drive pulleys I come across have been moved or moved on their own. usually I use 3/4 wrench on one of the locknuts for the adjusters on a rocker on an injector to find max lift, and check the position of the accessory drive pulley (or a dial indicator if I am feeling fancy).

I cannot remember the order off the top of my head, but when the injector rocker is at its max downward travel, you torque the adjuster on the rocker arm to 6 in lb. If you set a top stop injector to 125 in lb, you stand a very good chance of sticking an injector, especially if the injectors have very much use (the more carboned up they are the more likely to stick.
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coastalBend
Posted 6/22/2018 22:02 (#6828524 - in reply to #6828101)
Subject: RE: I just saw you picture in the OP


south texas
Not being rude but u are incorrect. The stc system is a top stop injector but with stc. Its in the older books. The oil lines going to the injectors is a dead give away plus ive had the injectors done twice with cummins literature coming back. The 6inlb is done at 0 load, ibc.

the 125inlb is in the book for the 855nta and n14 mechanical for obc.



STC Injector Adjustment (Outer Base Circle Method): Torque to 14 N•m [125 in-lb].


Use a dial-type torque wrench to tighten the injector rocker lever adjusting screw to the specified torque. If the screw causes chattering during setting, repair the screw and lever as required.

Hold the torque wrench in a position that allows the direct view of the dial. This is to make certain that the reading on the dial is accurate.

Torque Value:  14  n•m    [ 125 in-lb ]




Edited by coastalBend 6/22/2018 22:07
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blowsand
Posted 6/22/2018 23:47 (#6828689 - in reply to #6828524)
Subject: RE: I just saw you picture in the OP


mercer county, il
Ok, if that is what Cummins says that is what you go with.

I must have been mistaken, the only ones that I have seen that call for a higher torque setting with the injector pushed down completely are on the celect injectors to make sure all the oil is pushed out and you are just setting them against the springs.
I was taught to set them all the way down unless the nameplate gives you an injector travel distance, then you whip out the dial indicator, typically. With older injectors.

My apologies
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dvswia
Posted 6/23/2018 07:07 (#6828861 - in reply to #6828689)
Subject: RE: I just saw you picture in the OP


sw corner ia.
if that data plate says "5-6 in. lbs" like his does, that is what you do.

to coastal blend.. let us know how it works out.
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coastalBend
Posted 6/23/2018 08:01 (#6828966 - in reply to #6828861)
Subject: RE: I just saw you picture in the OP


south texas
Ive done this several times. Im not asking for me or about the injectors. Was asking why cummins literature says different valve lash settings for my engine than the tag without explanation. The change from ibc (6inlb) to obc (125 inlb) was explained in the literature provided to me with my last set of injectors. The obc method takes into account wear on the cam, followers ect, the ibc method doesn't have enough pressure to do that.

in 2014 i was having issues figuring out what my engine and methods should be, i ran the obc and ibc methods on the engine for my own knowledge, both came out almost exactly the same. Link to thread about it

https://talk.newagtalk.com/forums/thread-view.asp?tid=442230&posts=2...

this was before i received the literature about the obc method being preferred to take slack out of the valve train. Both methods were published by cummins, now with the change to the n14 mechanical book, the ibc method is not published anymore.

Edited by coastalBend 6/23/2018 08:15
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SDman
Posted 6/23/2018 08:26 (#6829013 - in reply to #6828966)
Subject: RE: I just saw you picture in the OP


I've got a very, very early 9380 CaseIH Steiger that has the 855 with STC around here as well(instead of the mechanical N14s all the rest of the 9370/80/90s use). When I ran the overhead on it years ago, I was told by Cummins to set it the same way you did(OBC-125 in. lbs.) for the reasons you mention. In regards to the old setting(5-6 in. lbs), you needed a special tool that we referred to as a "horseshoe". This tool would lock the injector to the tappet inside the injector for the STC system so that the tappet would not affect the overhead setting. Later on, they went to the OBC setting for greater accuracy.

In regards to the valve setting, they never said anything about deviating from the setting on the engine data tag. I thought Cummins used to list 2 different valve settings dependent on what the rocker lever housing(the piece that the rocker arms fasten to)the engine has-aluminum or cast iron. IIRC, aluminum rocker housing called for the 11/23 setting, while the cast iron housings called for 14/27 settings-but I could be wrong after all these years.
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coastalBend
Posted 6/23/2018 21:49 (#6830328 - in reply to #6829013)
Subject: RE: I just saw you picture in the OP


south texas
Now that makes sense on the valve lash settings. Thats something i was looking for. I dislike how they don't make reference to changes in literature.
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