another injector pop testing thread...

[IDIoit]

rookie pop tester.
my Misters pop anywhere from 1800-2000 psi.
ive read that 1900 psi is the target pressure.

a coupe of things id like to know, as other threads are pretty vague at best.

I noticed that some of these sticks are "catching" as some will pop smoothly.
and my spray patterns are all screwey.

what exactly is the spray pattern supposed to look like?
mine are a solid stream, and the smooth ones seem to spit straight, where others are spitting at angles.

whats the cure for leaky injectors?
if I hold the pressure just below pop pressure, they will dribble.
havnt had much luck with these injectors.
got them back from mel, and ran them for a total of about 60 miles.

7/8 are leakers, and no time to send them back.

picking up a set of BB injectors today, I hope they give me dribble free operation.

 

[mblaney]

Is your pop tester clean? If you are passing **** through the injector then you will see random dribblers. I suggest you clean it out real well. Put a dribbler on there and give it a blast of flow to hopefully flush it out. you might need a few pumps to get the crap out (hopefully). If this works you should have a consistent pop pressure (mine are around 1850) that vary maybe +/- 20 psi. You probably can't see that with your gauge though. After the POP, the injector should close at around 1400 from what I remember.

Your spray pattern should be a conical pattern, well atomized. If you are squirting to the left or a solid stream then something is wrong. Unless you are pumping a huge volume of fluid you should only see a quick pop though. You might have to take the injector apart to clean. Ultrasonic bath would be best for that. If you are diligent with cleaning and reassembly I don't think you will have a difference in the original set pressure.

I have a thread with a nice video here... will look for it. Has some good info for you.

Edit: Linky here http://www.oilburners.net/forums/sh...with-video&highlight=best+homemade+pop+tester

Put it in my signature also.

 

[IDIoit]

pop tester is bran new with a clean filter.

using #2 diesel straight from my fuel filter on my truck into a clean mixing container.

the gauge isn't very precise im thinking about putting a better gauge on it to get a more accurate reading.


I spend a shat load of coin on these injectors. and I would like to salvage them.

none of the spray patterns are conical. every one of them is a stream, and neither of them stream the same way.

are there different nozzles I can use?

when cleaning the injector guts, whats the best medium to use?

I do have a heated ultrasonic.

 

[mblaney]

Did you try blasting the injector using the pop tester? Sometimes there could be something small in there that will get pushed out if the injector opens enough.

Not sure if you have disassembled these before or not but I used a 12 point socket with an impact wrench to get it apart (hold body with a metric adjustable or a soft jaw vice).

For my bath I used biodiesel to clean. I filled the bath with hot water then put the parts in a beaker with the bio, suspend the beaker in the bath... don't have to mess the whole bath up.


Edit: I think the original injectors need the 12 point, the Delpi's will accept a 6 point socket.

 

[riotwarrior]

Depending on pump....sometimes easier see when hold down massive burst like Gqry does in his vid

 

[OLDBULL8]

Someone posted the Ford Specs on injectors a couple of years ago. Lost it when my puter took a dump. But the specs on the stream/atomization said it's not necessary for atomization for an IDI, due to the fuel being injected into a precup, but it's necessary for atomization for an DI, direct cylinder injection. The standard pop is at ~1850 for a NA, and ~2000 for a turbo, and a 50 PSI difference between all injectors. A leaky injector Is OK if the bubble hangs on the end for 15 seconds before dropping off with pressure on it just below the popping pressure.

This is what I recall from the Ford specs.

 

[79jasper]

Here's @icanfixall videos. https://youtu.be/G7YXCq4z1Ig

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[OLDBULL8]

My theory is that you don't get as much fuel out of an injector when the engine is running as you do on a pop tester. With the engine running at even idle at 650 - 700 RPM, the IP (standard DB2) only has time to "shoot" a small amount out of the injector in a fraction of a second, where as by hand pumping a pop tester, it's very slow compared to an IP shot, but it does prove what the popping PSI is, not how much fuel is comparably IP pumped.
In other words, a pop tester can reach the popping pressure before the end of the pop tester stroke and still be pumping fuel until the end of the tester stoke once the pintel has been lifted off it's seat.

 

[riotwarrior]

Well said Bill

 

[icanfixall]

Bill you stated exactly what is seen in my vid. You can see if I increase pressure till the injector pops then it bursts a small shot of fuel. But normally it will show the volume of what the tester stroke is.
Brian as for cleaning try what you have but keep all the parts in the injector they came out of. Don't mix and match parts from one to another. Do you know what micron the tester filter is? I feel the finer the better and less than 10 microns seems to work well. No idea why some of your injectors hang up during stroke of the pintle.

 

[IDIoit]

So I sat down and pop tested my misters again,
Along with a set I got from hydro-IDI
Both are Delphi BBs

What exactly sets the misters apart from the other?

I'm thinking about combining the 2 with the closest Pop pressure.

The one with the star, screams at you when you pressurize it.

I've got the others not to leak. Save 1,

You must be registered for see images attach

 

[OLDBULL8]

What exactly sets the misters apart from the other?

Brian, I would think you would have to ask Mel about that or go to Conestoga diesel, there web site should have an Ad explanation.

Moose Mister Mark II Injectors - The only performance injector on the market with an acceptable spray pattern. Dyno proven to develop better atomization and higher boost levels then comparable "pintle free" injectors. Juice up your engine without compromising smoothness or runability

EDIT
Looking at the injectors again, had to use the Magnifier to see the pop pressures.

The top row would be un-acceptable, but if they have been run some, they will have to be pressure adjusted.

The bottom row is just barely acceptable. I wouldn't touch them as long as there not leakers.

 

[IDIoit]

keep in mind, my gauge goes in 200 psi increments.
this is all just ball park, not precise readings.

im going to run the bottom set. and inform myself more about injectors.

remember, im a simple hotrodding gasser freak, I need time for things to sink in..lol sometime years.

 

[79jasper]

By "scream" if you mean the squeak, I thought that was normal?
At least most of the pop test videos I've seen.
Or were those few much louder?

Sent from my SAMSUNG-SM-G935A using Tapatalk

 

[bbjordan]

Proper Penetration

I've noticed a distinct "scream" coming from what I thought were good injectors when pop testing them.

You might be able to juggle the shims in the Misters to get the pop pressures all the same (good luck!). Withing 50 psi, I think you're doing good. Just match them to the cylinder's compression. Lowest pop pressure to lowest compression cylinder. My thinking is that an early injection on a low compression cylinder is less detrimental than an early injection on a high compression cylinder.

Regarding the spray pattern, here is some info from a IDI Super Tuning thread post 351:

" The Ford 6.9 and 7.3 diesels use the basic design of the Ricardo "Comet" pre chamber with center pintel nozzles.

The lab tests done at Langley in the early 1900-1920's and the design features of the Ricardo "Comet" chamber are basically where this information comes from.

This is more or less a over view of the thousands of lab test and patent's I have read and studied of the times put into my own words.

This style IDI chamber and center pintel nozzle has several distinct functions in the combustion of the fuel charge. The first function is for the injector to atomize a small amount of fuel (5 to 10%). This atomized fuel is mostly in the center and upper part of the chamber where the glow plug is located. This area is where the pre flame starts and produces more heat and mixing currents. Since the mixing currents in the center of the chamber are less predictable there is less predictable combustion of the fuel.

The next function of the nozzle is to form a very tight core charge (pattern) with the intent of this core charge hitting the very bottom wall of the chamber (the hottest part of the chamber). Then to spread out on the chamber walls into a very thin layer of fuel. There are several positive and more predictable key factors with this. These are some of them:

Very easy to test film layer thickness compared to injector pressure, quantity of fuel injected and design of the walls and predict the penetration of the core charge with different pressures in the chamber.(think N/A verses turbo and injector pop off of each)

The temperature of the walls are more consistent and controllable by controlling water jacket temperature.

The mixing currents coming through the small passage between the chamber and the cylinder can by design of the passage be more predictable and directed along the chamber walls for more effecient mixing of the available oxygen and fuel.

The "old science" focused on "proper penetration" of the fuel core charge hitting the bottom chamber wall of which then formed the proper "film layer".

If we assume the chamber walls are so designed to achieve the proper film layer with the proper penetration of the fuel core charge, then our thoughts should be directed on the variables that affect penetration.
Variables:

a clean injector (does not drip)
pop off pressure set in relationship to cylinder pressures expected (N/A or turbo)
sealing washer thickness
fuel quantity
fuel density

In the pre flame period burning the atomized fuel we are restricted to working with the depth of the glow plug into the center of the chamber once the above penetration variables are fixed."