Injector Depth??

[Sri Ram]

Putting DDP stage II injectors in. . . I have three different thicknesses of copper sealing washers: 0. 5mm, 1. 5mm, and 2. 25mm.



My stock injectors had the 2. 25mm washers. The DDP ones came with 0. 5mm washers but did not crush enough to seal the bore and so resulted in blowby around the injector. They put the new injectors approximately 0. 5mm deeper into the cylinder.



The next thickness, 1. 5mm, puts the new injectors approximately 0. 5mm shallower. They seal well at idle, but I haven't had the chance to road test.



The final thickness, 2. 25mm, would put the new injectors approximately 1. 3mm shallower. If I had a 1mm washer, the new inectors would be at stock depth, within a few tenths of a mm. My question is, does anyone have a spec on injector tip depth for maximum atomization and combustion?

 

[dpuckett]

If they are a 4 hole injector with a 9351 on the tip, they are marines that will not do well in our pistons, but the super thin washers will help out with smoke.



How did you get compression leaks at the injector? If you torqued the nuts down to 44ft-lbs, they should seal just fine.



Daniel

 

[Tippin Spotted Cow]

You know, I'm glad someone else brought that up, my BD's came with 2 different thickness washers also. I just matched up mine to the stock ones, didnt think twice about the actual depth of the injector into the cylinder.

 

[Sri Ram]

How did you get compression leaks at the injector? If you torqued the nuts down to 44ft-lbs, they should seal just fine.

Yeah, I know. It doesn't make sense. In fact, I still can't get #5 injector to seat well. I've cleaned the bore and installed it three times with new washers, torquing to spec and even beyond spec, but I still see anti-seize compound boiling between the injector and the locknut. Any ideas?

the super thin washers will help out with smoke.

So far the smoke is minimal except when cold. If I get on the throttle, it can get pretty bad, though.

 

[CBeeman]

Injector Protrusion



Injector Protrusion

mm in

2. 45 MIN 0. 096

3. 15 MAX 0. 124

The only way to measure this is to pull the head.

 

[Stanbery]

the anti-sieze will "boil" off for the first few minutes or so. i wouldnt worry about it, the same thing happened to me when i put my new incjectors in. everything ended up sealing up like it should. as far as the depth goes, thats a good point, i wonder what people will come up with for an answer.

 

[Greenleaf]

My question is, does anyone have a spec on injector tip depth for maximum atomization and combustion?

That's impossible to say IMHO. That would be directly effected by the tip design. Example would be the angle of spray pattern, the size of the orfice and the number of holes. This is also related to the piston and we assume you have the OEM piston. Also, the thickness of the head gasket. You still have the original gasket?

 

[Sri Ram]

The only way to measure this is to pull the head.

forget that!

the anti-sieze will "boil" off for the first few minutes or so. i wouldnt worry about it, the same thing happened to me when i put my new incjectors in. everything ended up sealing up like it should.

Only one of my injectors is boiling anti-seize. It's mixed with fuel and eventually runs down the side of the engine after a while at operating temp. This is not an acceptable situation for my engine.

we assume you have the OEM piston. Also, the thickness of the head gasket. You still have the original gasket?

yah, everything stock except injectors and items noted in signature.



My next step will be to swap the leaking injector with another on the engine to determine if it's the injector or the hole. I haven't noticed any other problems after putting these new injectors in. Unfortunately, I haven't noticed an improvement in EGT yet, either

 

[Greenleaf]

The holes need to be clean. You need to make sure there isn't a second seal washer down in there.

 

[Sri Ram]

The holes need to be clean. You need to make sure there isn't a second seal washer down in there.

They're clean, especially the one that's leaking. I used Cummins p/n bore brush and electrical contact cleaner to free up any gunk and then a home-made swab to clean it up. When I pulled the leaker, the copper washer had a good crush on the underside of the injector and no visible deformation on the bore side that would indicate debris or other impediments to sealing. I haven't had a chance to swap it with another injector yet.



BTW, these injectors come with a 30 day money back guarantee. So, I've got some time to play with them before making a final decision.

 

[Sri Ram]

Upon closer inspection, it looks like I may have mis-diagnosed the situation. Although the high pressure line and drain mainfold connection on the leaking injector were both torqued beyond spec, my leak seems to have been coming from those two areas. If I'm right, the fuel was then running down the injector and mixing with the anti-seize before going down the side of the engine. I tightened things up after the engine was warm and may have seated the fittings better. I'll run it for a day and see what happens.

 

[JLEONARD]

looks like I may have mis-diagnosed the situation

Oftimes the toughest part of solving a problem is defining that problem.

How do I know this? (Don't ask)

Glad it ended up being easy.