Nhc250 valve injector overhead adjusting

augiedoggy

New member
505
3
0
Location
Cincinnati Ohio
NHC250 VALVE INJECTOR OVERHEAD ADJUSTING

Many of my fellow Haspin rally attendees know that my M818 was quite smokey and running a little rough. So, after killing lots of bugs and sending a few prius drivers in the other direction, I decided it was time to address the problem. Mostly black smoke, with shades of blue and white. When taking off, a big cloud erupts.
Also the engine oil definitely had fuel in it.
Here it is at Haspin: [media]http://www.youtube.com/watch?v=MrAGR1T6rqA[/media]
After consulting with Will Wagner, I decided to get all new injectors and go through the “overhead” adjustments (valve and injector adjustments).
Install new injectors, follow TM torque procedure (72 inch lbs) adjust injectors then adjust valves (.014 in. and .027”ex). Cross fingers…..then…… it ran FAR worse and a lot more smoke! Oh $#@%!!!!!!! What did I do wrong?!
I’m using on older click type torque wrench, maybe I need a fancy dial type?
Oh, did I mention that the accessory drive nut is stripped out and just spins? I have to bump the engine around using the starter and try to turn it by hand using the fan to align marks!
A quick call to Will Wagner in sunny Ca. and he suggests that since the nut is stripped maybe the accessory drive pulley is not installed correctly throwing off the procedure.
Will outlined a way to verify the engine position monitoring the #5 injector rocker; with a socket and extension on the #5 injector, when extension moves over to the exhaust side (and both valves are closed) the 1-6 VS marks should align with the gear cover pointer. This seemed to be ok. {Did I describe this correctly Will?}
At this point I noticed that all 6 injector rockers had about an 1/8 th inch free play in the rocker (when its respective valve rockers loose) so somehow I screwed it up. Adjusted the injectors again; still smoking but a little better. I then decided that maybe my torque wrench is out of calibration and I went over the injectors again torquing them to 100 in lbs (adjusting the cylinder when the both valve rockers had play ignoring the timing marks) and the smoke improved!! Next increased torque to 150 in lbs……smoke even better! Finally torqued them to 200 in lbs. and the smoke is almost completely gone and runs smoother than ever! On the test drive, smoke is hardly visable at idle; no more cloud on accel but still leaves a thin trail of black smoke while cruising. But this is WAY better than before!
I still need to change the fueled out motor oil, but I want to make sure the problem is remedied before I spring for 8 gallons of motor oil. I believe the fuel in the oil may contribute to smoke.

Now for my questions. Is my torque wrench that far off? Do I need a good quality dial type torque wrench? Am I compensating for a pump problem by over torquing the injectors? (as I understand it, the tighter the injector the less fuel it delivers??)
Accessory drive pulley nut ordered from local cummins dealer; fingers crossed that the shaft threads ok.

Apologies for being so long winded, but maybe my story will help someone, and any advice you guys can offer would be greatly appreciated!

A huge shout out to Will for talking me through this and his patience in dealing with me (on a Sunday even!).
 
Last edited:

gimpyrobb

dumpsterlandingfromorbit!
Steel Soldiers Supporter
27,659
223
63
Location
Cincy Ohio
Will is a good one, especially at the museaum! Was that my torque wrench that is out that far? Its a snap-on, I wonder if they can get it dialed in as warranty fix.
 

augiedoggy

New member
505
3
0
Location
Cincinnati Ohio
Will is a good one, especially at the museaum! Was that my torque wrench that is out that far? Its a snap-on, I wonder if they can get it dialed in as warranty fix.
Hey Gimp that was my coworkers old torque wrench, I was afraid to use yours as it seemed a little overkill being 1/2 drive. (1/2' drive in lbs? who-da thunk?!)That is an old one. I believe snap-on would tell you that old wrench is not serviceable anymore, but would gladly sell you a new one!!
In hind sight maybe I should have tried it
aua
 

jimk

Active member
1,016
22
38
Location
Syracuse, New York
I was unable to set mine with a torque wrench. At 15in*lbs the spring(s) would start to compress. As I continued the spring compressed further with minimal torque increase. At 25in*lb the plunger(s) bottomed out solid and torque went up fast. Looked wrong and was a huge change from where they were. I was worried about breaking something so stopped and set them with the dial method (.170". which is about were some were before). Runs fine. Can anyone point out what I was doing wrong?

Dial method- TM 9-2320-260-34-1, section 3-82 page 3-237

Also, years ago my pal was having problems torquing mains on a 427 Chevy and asked me to take a look. The bolts were all badly stretched. He thought they were bad. I put my beam type wrench on his Snap-On click type. His was about 100lb*ft too high. Click types need to be set back to zero when you are done.
 

pctrans

New member
Steel Soldiers Supporter
1,925
17
0
Location
Bradenton, FL
Only thing I can add, from recent experience, is that the TM torque method is WRONG! A recent thread documents my issues. Ended up replacing all injectors, and didn't need to. aua Had a Mexican guy, that graduated from Cummins college in Mexico, run the rack and my 816 purrs like a kitten now. He "no hablo english", so I can't tell you his procedure. But I do know he adjusted the injectors and valves on each cylinder at the same time, without a torque wrench.
 

mckeeranger

Member
779
0
16
Location
Eastern Kentucky
Only thing I can add, from recent experience, is that the TM torque method is WRONG! A recent thread documents my issues. Ended up replacing all injectors, and didn't need to. aua Had a Mexican guy, that graduated from Cummins college in Mexico, run the rack and my 816 purrs like a kitten now. He "no hablo english", so I can't tell you his procedure. But I do know he adjusted the injectors and valves on each cylinder at the same time, without a torque wrench.
I ran into that as well. One of the charts, indicating which valves to adjust at a given timing mark, is wrong. You adjust the injector when it's in the closed position, but the chart had me torquing it when open. When it tries to close, it's already closed. A bad way to ruin a good injector.
 

WillWagner

Loose Nut
Super Moderator
Steel Soldiers Supporter
7,574
204
63
Location
Monrovia, Ca.
There are two ways to set the overhead on an 855. One is the outer base method and the other is the inner base method. The inner base method can ONLY be used on top stop style injectors. The accessory drive pulley is marked differently for the IB method, TDC1-6, A, B, C.
Most of the NHC's that I have seen are marked TDC1-6, VS1-6, 2-5, 3-4. That is used for OB method.

A little schooling first. The base timing for the engine is done by aligning marks on the crank and cam gears. The injection timing is done with shims under the cam boxes by measuring the positive end of injection, (or beginning, I've had instructors tell me both), when the piston is at .203 BTDC. The pumps don't need timing on these, but, the part that drives the pump does. That would be the accessory drive. The accessory drive can be removed and put back into an engine that runs fine w/o timing it to the cam. Nothing physically changes when that happens, it will run the same, however, the next time that someone needs to go into the overhead, they'll be screwed. The pulley that has the marks on it for the overhead set is pressed onto the shaft that needs to be timed to the base engine..the accessory drive shaft.

On an engine that uses top stop injectors, (top stops have a barrel and jamb nut that sets the travel of the injector to match the cam's outer base circle, you can't see the spring on these injectors), an easy way to check to see if the accessory drive is in time is to align the pointer and A on the pulley. The overhead set for top stops goes like this;
I V
A 3 5
B 6 3
C 2 6
A 4 2
B 1 4
C 5 1

Hang an overhead wrench on Injector 5, and bar the engine over while watching the wrench, don't watch the pulley. When the wrench starts to move, ramping up to the OBC on the cam, STOP. Look at the mark. It should be within a 1/2 inch of the pointer...either way...the acc drive is in time, GTG with setting the overhead.

On an engine that uses non top stops, you can check this from the get go, but not as you go through the tune up steps if the engine has been apart. Non top stop injectors have no barrel and jamb nut to set the travel. That's why the overhead set is different. The injector is set on the outer base of the to a specified torque sufficient enough to load the push tube and seat the plunger so the compression in the cylinder won't go back into the injector after positive injection ends. It also plays with injection timing. A loose setting and injection starts later, (slow timing), and a tighter setting starts injection sooner, (fast timing). The same can be done when setting top stops, NO performance gains can be made here. If you wanna mess around with timing for power, smoke, etc. it needs to be done at the cam boxes. The only thing a loose setting does is carbon plungers and tight...too tight... of a setting bends push tubes. Back to acc drive timing. The OBC of the cam is roughly 60% of the lobe, so when the pointer and VS1-6 are aligned, the injector lever for 1 might very well be down, but you have no idea where it is in that 60% of OBC. When any of you attempt to do anything in the overhead, use the above outlined method of checking the timing BEFORE you start disassembling things. If for some reason it isn't in time, PM, e-mail or call me and I can walk you through re marking the pulley.

The overhead set on the NHC for the OBC method goes like this;

A 1 or 6
B 2 or 5
C 3 or 4

Set the valves and injector on the same cylinder, in firing order, setting the injector first to load the rocker shaft,

We'll start with A being cylinder 1 and first in firing order. The injector lever should be down, the nose of the lever pushed down toward the injector. Both valves need to be loose. You can use a click or dial type torque wrench, just make sure it is a known good wrench. The screw shouldn't move much if you are just tuning up, but, if the engine has been apart or you put another injector in it, the screw and injector lever will move quite a bit. You will need to torque the injector screw to 68-72 INCH pounds. That isn't much, but the injector spring tension will be overcome by it and, again, if the engine has been apart, the plunger and nose of the injector lever will be pushed down into the injector, that is what you want, remember you are setting the injector on the outer base circle of the cam..in it's farthest downward position. Lock the jamb nut down...IIRC 40 ft lb and move on o the valves. .014 intake, .027 exhaust. The cross heads are adjustable also, but we'll keave that for another time. Bar the engine over to the next mark, VS2-5, 2-5, sometimes they are marked different, and go through the steps again. 68 to 72 INCH pounds on the injector and .014 and .027 on the valves. Bar it again and repeat. If for any reason it gets hard to bar over...other than trying to overcome the engine compression STOP, something isn't kosher. Loosen things up, regroup and start over. You'll know if the difficulty in barring is from compression if it gets hard and you stop and wait a few seconds and you can continue on and it's easier. You'll also hear a "hissing" noise coming up through the push tube cavities as each piston is brought to TDC on the compression stroke.

I'll see if I can dig up some books with pics, scan them and put them up in the 5T section. I'd make a vid of it but I don't see this stuff at work any more. If anyone by me wants to do a tune up, we could do one here, go through the motions on R&I ing an injector, checking timing and tuning up and put it on digital so it can be posted here as a sticky.

Hope that doesn't confuse anyone. If you need help, you know how to find me. :beer:
 
Last edited:

augiedoggy

New member
505
3
0
Location
Cincinnati Ohio
WOW Will, Thanks for the schooling. It helps a bunch to have a good understanding of how it works and should work. I'll have to get my stripped acc. drive nut remedied and run through this again.:cool:
 

augiedoggy

New member
505
3
0
Location
Cincinnati Ohio
Quote:Hang an overhead wrench on Injector 5, and bar the engine over while watching the wrench, don't watch the pulley. When the wrench starts to move, ramping up to the OBC on the cam, STOP. Look at the mark. It should be within a 1/2 inch of the pointer...either way...the acc drive is in time, GTG with setting the overhead.

Will, just to be perfectly clear on this part, which mark should be lined up with the pointer as #5 injector starts to move, 1-6VS ?

Thanks!
 
Last edited:

augiedoggy

New member
505
3
0
Location
Cincinnati Ohio
I've got it set correctly now and running great!
My torque wrench and a lack of understanding of basic operation was my problem.

After verifying the timing marks on the accessory drive pulley(I used a dial indicator to watch the movement of the #5 injector because turning the engine by hand was very slow) the injector torque went smoothly with my new in lb torque wrench. When the rockers are loose the injector should be closed (rocker arm is pushing it closed [like a valve rocker open]) with marks lined up set to 72 in lbs.
Like jimk said the torque goes up fast because the injector is closed and will not travel anymore.
Definitley do not overtorque or you could bend/damage something.

I hope others will benefit from my trials and tribulations :beer:
 

802dot1q

New member
123
2
0
Location
SoIL
I'm lost. According to Will above, A or 1-6 VS you should adjust cylinder #1 injector then valves? *The 34 has me adjusting injector #3 and valves on #5?
 

jaxsof

New member
586
15
0
Location
Dundalk, MD
From my 1994 manual:

Seems pretty straight forward. Not doubting you Will, just wanted to see where the discrepancy came from. And, to be honest, I thing someone may have an old manual, maybe need to submit a DA2028
 

Attachments

augiedoggy

New member
505
3
0
Location
Cincinnati Ohio
I'm lost. According to Will above, A or 1-6 VS you should adjust cylinder #1 injector then valves? *The 34 has me adjusting injector #3 and valves on #5?
I am FAR from an expert on this but, I lined up 1-6VS and verified that cyl #1 valve rockers were BOTH loose (valve freeplay) then followed table 3-7 for the torque method. I believe it is true that if BOTH valve rockers have freeplay on any given cylinder (and its perspective timing marks are lined up), that cylinder is essentially in the firing position and the injector MUST be closed. For clarities sake, "injector closed" means the rocker is pushing the plunger down. (the injector remains closed for 60 degrees of cam rotation).
 

802dot1q

New member
123
2
0
Location
SoIL
I just went though this procedure and thought I should post my $.02 and the process I used with very good results.

1. Forget the procedure in the 34 TM. Seriously.
2. Read Will's post #8 here.
3. Read Will's post #8 here again. Understand it.
4. Line up VS 1-6, VS 2-5 or VS 3-4. Doesn't matter where you start. Let's say VS 3-4 was the closest and you are lined up there.
5. Look at the valves on cylinders 3 and 4. One of them will have both valves closed - one will have one valve open. You are going to adjust the one with both closed. Follow Will's info from above.
6. Move to the next timing mark, check for the cylinder with the TWO closed valves. Adjust. Repeat until you hit them all.
7. If you notice you will be following the firing order.
8. Buy Will a beer for the good post.
 

JarheadMtn

New member
356
2
0
Location
Anaconda Montana
Will gave great insturctions on how to adjust everything. I had read about using a socket and ratchet to turn the engine over and was having lots of trouble since the fan was in the way. Talked with Will and he told me about the Cummins engine turning tool. Ordered one on Amazon and it made it so much easier!!! The engine purrs now and no smoke!
 

WillWagner

Loose Nut
Super Moderator
Steel Soldiers Supporter
7,574
204
63
Location
Monrovia, Ca.
Just a bit of advice here. DO NOT use a screwdriver that has magnetic changeable bits. The bit will fall out and go down into the pan. The bit in the pan isn't an issue, the issue is that if the tool DOESN'T make it to the pan and gets lodged behind the cam follower lever. That will cause the cast iron housing to BREAK when the follower is pushed upwards by the cam. use a normal #3 flat blade screwdriver like this...I have one like this here at home and a Snap-On one like this but better at work.
 

Attachments

Zoidsfan77

Member
48
0
6
Location
Columbus, Ohio
Just a bit of advice here. DO NOT use a screwdriver that has magnetic changeable bits. The bit will fall out and go down into the pan. The bit in the pan isn't an issue, the issue is that if the tool DOESN'T make it to the pan and gets lodged behind the cam follower lever. That will cause the cast iron housing to BREAK when the follower is pushed upwards by the cam. use a normal #3 flat blade screwdriver like this...I have one like this here at home and a Snap-On one like this but better at work.
Forgive me Will, but how does one apply an accurate torque using a screwdriver? (Assuming injector adjustment).
 
Last edited:

sandcobra164

Well-known member
2,969
127
63
Location
Leesburg, GA
Mr. Wagner,
Just to help clarify in my own head. The injector actuation is pushed down or "closed" for most of the duration of the camshaft and the actuation is lifted or "raised" for the actual injection of fuel into the cylinder. I read your post a few times and that's my take-away but I want to be sure before I run the rack on my 250. It makes sense to me so far but I have another question. How does the injection system take the 170 to 200 psi of fuel and spray it at injection pressures required to make a diesel run? I always had it worked in my head that the injector was a "positive stroke" driven by the camshaft but instead, the camshaft holds it closed until injection is called for in this scenario. Help me understand. I think I need to go through mine as it smokes quite heavily at idle. Quite a bit can be attributed to the 50/50 centrifuge filtered waste ATF/Diesel mixture but I think a good overhead adjustment would give me piece of mind. My Deuce ran the same mixture and never smoked at idle but I am aware that it had a much higher compression ratio which would account for the cleaner burn of the fuel mixture.

Respectfully,

Joseph
 
Top
AdBlock Detected

We get it, advertisements are annoying!

Sure, ad-blocking software does a great job at blocking ads, but it also blocks useful features of our website like our supporting vendors. Their ads help keep Steel Soldiers going. Please consider disabling your ad blockers for the site. Thanks!

I've Disabled AdBlock
No Thanks