adjusting injectors by hand?

[hjalbert]

I read hagars post, about the pitch of the threads, but I don't get it. You may be able to decrease breaking pressures, by not tightening the housing as much (at the risk of leaking), but with out lapping or changing shims I don't understand how you can increase pressures. Maybe I am misunderstanding the concept.

[Fatmobile]

Great idea,
to pull some of Hagar's points out of his saga so they can be found easier during a search.

As I understood it;
the goal isn't to increase breaking pressure.

It's to determine if each injector is close to the same,
to see if each spring is depressed the same distance.

For those who haven't read about it:
Screw both halves together,
when the slack is out, you can feel it.
Make a mark.

Tighten it the rest of the way and see how far it moved.
I usually get more than 270 degrees.

I've checked it a few times and it's accurate,
it can tell you if one injector is going to have lower pressure.

[hjalbert]

I see, so you are essentially using the injector body to measure the springs "free height" at the point that resistance starts, and once the top half makes contact with the intermediate disc/spacer, and everything is sealed together, that would be the amount it compressed the spring, which would be the amount of force increase the pressure would have to overcome to compress spring up wards for nozzle to open. (Assuming all springs are worn the same, and still have the same rates to begin with.) I really wish I could find some shims locally. I have been doing a lot of thinking about this whole system. I wonder if by using lapping on the bottom of the top half of the injector, and on both sides of the spacer/intermediate disk in order to increase breaking pressure it in some way affects the timing as well in that injector, as you have essentially decreased the quantity of fuel that the injector contains. Granted its minuscule.

[hagar]

hjalbert and ALL : I should have said can we set Injector opening pressure , without a Testing machine ?.

Yes we can , by using pitch of Barrel thread.. We use the numbers from the Bentley (think shims) The Pitch can then be used to find compression of spring. We can feel when the compression of spring starts (by hand) then we turn barrel to it comes to the end of compression (using a wrench). I have a number of commercial (factory made?) testers. I was amazed by how close I got to the Bentley specks. SO? I realized that many a newbie could make use of that procedure . I am pleased to see that I did not waste my time.. Shims are expensive. According to my Bentley 71 PSIG per 0.05 mm.

To complete we use a torque wrench .

I wish someone who understand the procedure would rewrite this entry...

hagar.

PS : I think Fatmobile got the hang of it. Worn springs ? I never seen one.I measured countles BOSCH springs .All were right on the money. German Precicion..

[Fatmobile]

Thanks for the info Hagar,
I keep quite a bit of what you've said in my head,
but it doesn't always stay there.

Sooo glad this important info was pulled aside, focused on and written down.

[Ira B]

Hey Guys,

I'm not quite clear on how this works?
If you just use a torque wrench to tighten them then why mark them?
(sure I'm missing something here so try to keep the jeers down )

[Fatmobile]

I mark them where they first contact the spring.
That way I know how many degrees the housings are rotated before they seat.

The more degrees =
the more the spring was compressed =
higher breaking pressure.

From the time the springs begins to compress,
to the time it seats,
has always been less than 1 full turn for me.

Hagar?? What is the thread pitch?
1mm?

If it is;
then 270 degrees would be:
.75mm
devided by the .05 Hagar gave us from the Bentley, gives us:
14.5

71 psi for every one of those =
1029.5

1 full turn would be=
1420psi

That's pretty low and very fine thread,.. but it sure made the math easier
I think one turn gives you more psi than that so the pitch might be steeper,..
might be 2mm per 360 degrees.

[Ira B]

That you for switching on the light bulb.
It makes perfect sense.

[hagar]

Maybe I am misunderstanding the concept.. said hjalbert . Yes you are said hagar., You need to study a BOSCH injector.

The concept ? it is a fast way to find the correct shim's. Found them ? then we use the torque wrench..

Here is how I find the pitch of threads I can't find my Machinist book right now..

I take a barrel top and bottom NO internals. Then I measure one turn with a Machinist Caliber . Micrometers , how do they measure distances ? they use a very fine thread. I better mention Mark Shepherd he uses the pitch to set the I P . Same concept for those who do not have a dial indicator. Quantum-man. is correct.. Use a bolt.

hagar.

PS : I hope you got the concept

[Quantum-man]

I mark them where they first contact the spring.
That way I know how many degrees the housings are rotated before they seat.

The more degrees =
the more the spring was compressed =
higher breaking pressure.

From the time the springs begins to compress,
to the time it seats,
has always been less than 1 full turn for me.

Hagar?? What is the thread pitch?
1mm?

If it is;
then 270 degrees would be:
.75mm
devided by the .05 Hagar gave us from the Bentley, gives us:
14.5

71 psi for every one of those =
1029.5

1 full turn would be=
1420psi

That's pretty low and very fine thread,.. but it sure made the math easier
I think one turn gives you more psi than that so the pitch might be steeper,..
might be 2mm per 360 degrees.

Pitch is 1.5mm, Spec 0.05mm per 5 bar. So 1 rev is 30 x 5, or 150bar, assuming linearity of spring...

[Fatmobile]

That sounds about right.
A little more than one turn for the 155 bar turbo diesel breaking pressure.
All the 135 bar NA injectors I've done were less than a full turn.