Injector calibration on a pop tester

[JFettig]

First off, this thread is NOT for bashing, not for advertising, not for flaming, its for education!

Secondly, I sold all my pop testing equipment, I'm not pop testing stuff for you guys!

This is not a guide for n00bs, seatman: feel free to watch.

If you want to talk about how x process is better than y process in an ignorant manner, go elsewhere.

Images are unedited, I'm doing this quick because I just want to put this out there without putting much time into it, feel free to add constructive information

This thread is mostly about how to do 2 stage injectors.

First step - lap nozzle backs. Use a piece of flat granite and 400 grit sand paper
before:

during:

after:

The purpose of this is to ensure the needle is exactly flush with the back of the nozzle. this is primarily for setting the 2nd stage. You might have to lap these again if it leaks down fast above the first stage pressure.

It is extremely important that you don't pull the needle out, mess with it, or anything after lapping, look at all the grit in there!

Next, give them a bath in simple green/water in a HF ultrasonic cleaner:

The grit will come out, needle will fall out when you pick them up - usually, be careful. Take one out at a time, do not mix them up!!!

 

[JFettig]

With the needle still out(keep track!) give them a big juicy spray of brake cleaner

Next: with your harbor freight vice with soft jaws, clamp onto an injector

crack nozzle nut loose and start turning it off

hold up a sec and clean off the soot

remove nozzle, needle, and nut

put your finger just above the hat and give them a high pressure squirt of brake cleaner to clean off any soot

 

[JFettig]

Race 520

Clean your nuts

Install nuts, turn it down until you feel it contact, add 30 degrees rotation(lots of other specs are out there, this is what I use)

Connect to pop tester

With the gauge shut off - knob turned all the way in, chatter test, crank the crap out of it. This does a few things - it seats all the components, and it tests to make sure it pops correctly - you'll hear it. Open air spray test afterwords, I didn't take a pic of that

Loosen knob, check pilot pressure. its a procedure to get it cranked up exactly to the pop and let it fly. I turn the shut-off knob to do it accurately

see video
http://vimeo.com/64677326
This shows it popping at 190bar, you can also see leakdown, this is very good, Bosio R520 nozzles are some of the better ones I've seen for leakdown other than Bosch.

This one is low. I set the pilots on R520 between 230-240bar

 

[JFettig]

Pull it apart, lay components out on a clean surface

you can see the main pressure shim

dump out the guts, keep track!

Special tool: paperclip with special bends

remove pilot shim:

measure pilot shim:

Generally, every .001" is approx 5 bar, I needed to go from 210bar to 240bar.

Box of shims, lots to choose from:

re-assemble, test see video
http://vimeo.com/64677328

 

[JFettig]

here is a #3 injector, be careful not to damage the needle lift sensor!

On to the main stage, this is easy.

Standard hat:

lock-out hat:

Its extremely important the lock-out is made to exacting dimensions, I'm talking tenths.

Remember when I said it might need to be lapped again?
http://vimeo.com/64677330

Main pressures are almost always high, look at how high this one goes from a simple nozzle swap and pilot pressure increase(yes, pilot pressure adds onto the main)
http://vimeo.com/64677329

 

[JFettig]

Changing the flow on a nozzle is easy, but you must have digital equipment as far as I know, popping into a beaker probably won't work.

To reduce flow, remove material from the back of the nozzle, not the needle, leave the needle sit a few tenths up, to increase flow, remove from the back of the needle. Its impossible to pop test the 2nd stage once you've done this.

 

[davebugs]

I NEVER plan on doing this - or obtaining the equipment to.

But thanks for the writeup.

Certainly helps a fella understand whats involved.

 

[LNXGUY]

Great write up!

 

[sirpuddingfoot]

Demystifying!

 

[AARodriguez Corp.]

I think this thread deserves a "sticky"

Wow!

 

[Chris Tobin]

Hand lapping on the granite seems a little risky to me... If you are removing any material, wouldn't you run the risk of inducing an angle to it, as it would be difficult to hand hold it at exactly 90-degrees...

Do the shops that offer balancing/pop testing do this by hand or use machines/jigs to do it?

Just wondering, not trying to question the methods or anything...

 

[JFettig]

Not sure Chris, hand lapping takes off .001" at most, most have only needed tenths lapped.

 

[Chris Tobin]

Ya, I guess with 400 you can't take too much off... I would still be concerned with getting pieces out of square with each other though... I'm curious what shops that offer this service do? Do they have a jig or machine to do it, or are they doing it by hand too???

 

[FlyTDI Guy]

It is tough to get something perfectly flat by hand. If you use straight strokes, you'll take more from the leading edge. Small circular motions tends to work the outer edges more than the center. If I get one that is stubborn and leaks, first step is re-clean, then I tighten more (reasonably so), then as a last measure swap into another body. If none of those work, it's time to send it back for another. Usually it's a clean issue and solved by one of the first three methods. Without proper milling equipment, trying to flatten by hand is a risky crap shoot and very technique dependent. They should already be flat well beyond hand methods from the factory. JMHO...

 

[JFettig]

One shop I talked to uses the same technique I use.

For the first set I jigged them up on a surface grinder - way too much work!

 

[FlyTDI Guy]

I guess part of me just is concerned that anyone trying this could make matters worse by slumping edges. "A little knowledge" kind of thing... Kudos on your success with this technique. The uber-hard surface is in your favor and LIGHTLY cleaning up the surface may increase the odds of a 'no leak' situation significantly. I've only had a couple stubborn ones and have always been able to get them to stop leaking without sending them back. Carry on and good info for those who are looking at doing their first nozzle swap.

 

[Chris Tobin]

It is tough to get something perfectly flat by hand. If you use straight strokes, you'll take more from the leading edge. Small circular motions tends to work the outer edges more than the center. If I get one that is stubborn and leaks, first step is re-clean, then I tighten more (reasonably so), then as a last measure swap into another body. If none of those work, it's time to send it back for another. Usually it's a clean issue and solved by one of the first three methods. Without proper milling equipment, trying to flatten by hand is a risky crap shoot and very technique dependent. They should already be flat well beyond hand methods from the factory. JMHO...

I agree and that is what I was talking about...

One shop I talked to uses the same technique I use.

For the first set I jigged them up on a surface grinder - way too much work!

That scares me a little...

 

[JFettig]

I don't know why you should be scared... surface grinder, not bench grinder! more accurate than lapping.

 

[Chris Tobin]

I don't know why you should be scared... surface grinder, not bench grinder! more accurate than lapping.

Not the surface grinder, but the shop doing it by hand... sorry for the confusion

 

[JFettig]

Feel free to give it a try, its not that big of a deal.

 

[KERMA]

One shop I talked to uses the same technique I use.

For the record... not kerma or DBW
We do not modify the nozzles, nor does DBW, we don't recommend it, and it voids any warranty

 

[burpod]

good stuff jon!

 

[GTiTDi]

Jon- great write up! I have all the same tools, just don't have a shim set.

 

[Digital Corpus]

A sheet of glass would be a good substitute for the flat surface.

So, for a random question to add into the mix: if someone did lap the nozzle down to reduce flow and then lapped it againtonincrease it back, how much of a tolerance is there to remove material before there is an issue with mounting the nozzle correctly?

 

[JFettig]

Glass isn't as flat as a granite surface plate but in a pinch, I suppose.

The distance the needle protrudes is less than .002" so it would lap off quick, the problem is now your pop pressures are now up to 10bar low. Lapping takes off only a tiny amount of material, if you're worried about the tolerance, you're doing it too aggressively.

 

[Seatman]

Hey JFettig, thanks for the special mention, it makes me feel all warm and fuzzy inside to be that important to have my name up



Other than that I think I'll leave the rest to someone a bit more careful than me lol, I don't think the injector would do to well after I'd been at it!

 

[Houpty GT]

Not sure Chris, hand lapping takes off .001" at most, most have only needed tenths lapped.

I work with hardened steel. If you use 150 grit paper, it is an effort to remove .0001" of material. 320 grit barely changes the surface. Lapping is not intended to cause any dimensional changes. It merely is knocking down the high spots on the surface. I would think that if you have new quality nozzles, then there is no need to lap them since the factory should be doing this. Used nozzles may be a different story. I would recommend lapping the face of the nuts since they have soot build-up and need to seal the combustion chamber with the copper washer.

Thanks for posting this.

 

[Dorkage]

So where can we get a box of shims like you have?

 

[SkyRyder55]

when lapping stuff, a figure 8 pattern is the best to avoid uneven wear. as well a lapping machine could be used. If I ever did my own injectors i would use the lapper at my work.

 

[morpwr]

Excellent

I think that was great write up. You have lots of experience information, plus the videos. I would try this based on your information. If lapping is that bigga deal, just bore a hole in a peice of steel, to hold the nozzle square. The figure 8 is a good procedure. Excellent post.