Adjusting D4400 injectors ?

[OlCatBob]

Hey Guys, yeah, it's me again... I have a D4 I'm trying to set for 1500 psi cracking pressure, but don't really know the procedure. I have removed the cap so as to get to the lock nut and the little squared adjuster; but don't know if I should set a pre-load on it or if it just bottoms out. Any insight as far as a "starting point" on it? Any and all help would be greatly appreciated.
Thanks so much,
Bob

[SJ]

I have had 100s of them out at the dealer but we always sent them to our fuel inj. lab. & had them set correctly with the tester. You can play around with them but will you ever know if it,s right. Maybe if you have a fuel inj. shop near by they can do it or check with your local Cat dealer. Have you ever checked or set the lifter screws in the inj. housing? They get set at 1.734" with that particular cyl. on TDC firing stroke. When your coming up on TDC firing stroke for that cyl. the lifter screw will just be starting up from it,s bottom position in the housing.

[OlCatBob]

Hey SJ, I'm actually trying to adjust the injector nozzle, I have actually found the poop that someone (I can't remember who) posted as to the way to take them all apart. I also, after finding that, realize that the little screw and locknut justt under the cap is to limit the lift of the injector nozzle. Right now, I came in to look at the pics again to determine how to get that next cap off. It's actually a lock "cap" that holds the adjustment in place. Thanks for the input, but I'm hoping I can still figure this thing out. All input is still worth the effort though.
Thanks guys,
Bob

[SJ]

Bob, I know what your trying to check out there but if they were set up with a tester they would be right.Yes they can be taken apart etc. where the later capsule type like in the D315 D4s & all the rest of the engines in that era all you can do is check the pressure or flush them out with the pressure tester & if they,re bad & won,t come up to the correct breaking pressure range you install new ones.

[Old Magnet]

Adjusting Unseating Pressure:
Remove the cap
Remove the lift screw lock nut and back the lift adjusting screw off approx. three revolutions so it will not interfere with the pressure adjustment.
Loosen the pressure adjustment lock nut and adjust the unseating pressure then tighten the lock nut (may take multiple adjustments to get it right)

Adjusting needle lift:
Correct needle lift is .007
Replace lift adjusting screw lock nut. Turn lift adjusting screw down lightly against the fuel valve spring stem.
Set up a lift screw adjustment fixture to obtain .017 measured with a thickness gauge between the fixture and the lift adjusting screw.
Remove the thickness gauge and back off the lift adjusting screw until .010 clearance exists between the adjusting screw and the fixture, after the lift screw lock nut has been tightened. The adjusting screw has now been backed off exactly .007 which provides the correct needle lift.

[OlCatBob]

Hey folks, just to update everyone, I got the injectors adjusted to 1500 psi with the HandyDandy pump I made. Found one where the flame plate had slipped off the pins, but found another nozzle where the pins weren't mashed flat. Fuel just gushed out the side before I took it all apart to see what was wrong. I believe I have solved these things at last!
I did run into a new problem when I went to change out the injector on #3 cylinder on the 2T. I got some help from my neighbor to hold the socket on the injector nut, and commenced to "break" it loose. Well... I'm not sure what broke loose, but I'm thinking it may have been the pre-com chamber. Any ideas on how to address that issue? I am thinking I will re-drill the hole to wherever the pre-com is now, and put the hex head pin back in. Any better ideas?
Thanks for everyones help, but solved the .007" by counting the tpi and found it was 24, which ended up being a shade less than 1/3 turn (.008")
Thanks all, Bob

[Old Magnet]

Combustion chambers should be torqued to 200 ft. lbs then the anchor screw is installed.
Thread count/rotation of the needle lift may get you in the ball park but it is not as accurate as the jig and feeler gage method. You can loose .001 or more just by locking down the retaining nut. May very well be better than what you had before though if someone has been playing around with the injectors.

[edb]

Hi Bob,
at the dealer we had all the requisite tooling but now you and I do not. I feel it can be adjusted by screwing the lift adj. screw lightly against the needle stem, as OM said, and then with a vernier caliper measure carefully the overall length of the injector assem. from the nozzle retaining nut face to the top of the needle lift adj. screw--(NLAS), being careful to keep measuring from the same position on the nozzle retaining nut face, with a little tension on the NLAS lock nut back the NLAS out to the 0.007" extra length overall (needle lift clearance dimension) and lock the lock nut, and recheck the dimension, keep adjusting until the desired length overall is achieved--even with the correct tooling the dimension changes with locking the lock nut but the variance is lessened with some locking pressure on the lock nut and NLAS. It becomes a matter of perserverance to get it correct.
NOTE I would and always did err on the side of 0.007" +0.001" - 0.000". A little extra lift is preferable to too little to save extra loading on the cam and lifter to try and force fuel through a lessened lift opening and causing these items excess unwarented loadings--orifice effect--extra lift, in excess, will cause black smoke at high idle with light loading on the engine.
I experienced this phenomenon with my British Thornycroft trucks' Gardner Diesel Engine when I rebuilt it, the valve opening pressure was correct but I had black smoke at high idle top gear on a flat road, when we encountered a hill it would clear up as more load came on. I thought about this long and hard and decided to apply 0.007" needle lift by lapping the nozzle body length down to give the 0.007" needle lift and cured the problem. There was nothing in my Gardner books about needle lift amongst the Injector repair section.
Hope you can decifer this rambling and you and others can put it to good use.
Cheers,
Eddie B.

PS someone posted that an ordinary ring spanner of a suitable size would fit the splines well enough to undo--do up the splined sections of the injectors, I have yet to get time and remember to check this out!!!

[Old Magnet]

Hi all,
Was going by the instruction book on setting the lift. It is quite specific on "exactly .007 dimension". The suggested tooling would be simple enough to do but I think I would set things up with a dial indicator if I was doing it. Then you can see what's going on.

[Bill Walter]

Chapter One has the tools and testing equipment to this job right. My E-mail is: wltrbet@aol.com I'll send you the prices of adjusting nozzles, pumps and etc.
Bill Walter, Kansas City, Mo.