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Discussion Starter #1 (Edited)
Hi.

I don't really need any help. Just thought I would share some pictures of the content of a spica fuel injector.
Perhaps it can be of interest for someone.

Note. The parts are a bit dirty. The images was taken before cleaning. Also, inside the black tube there is a VERY small brass part. Did not know this when I took the photos. Be careful not to loose it. It is only a couple of mm big.
 

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They are very trouble free as long as the fuel system is kept clean. On injectors that have sat derelict for a long time, soak them in fresh gasoline for a week or two before using. The operate at about 350 psi, so they are somewhat self cleaning.
 

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Discussion Starter #5 (Edited)
I have the head of at the moment and I thought I might as well take the injectors apart and clean them. I happen to have a small ultra sonic cleaner and I thought it couldn't hurt.

I have only taken two of them apart so far. One of them was completely clean but the other one, the one in the pictures had some strange residues in it.

The first part on the left in the picture has a "net" made of small spirals. It almost look like small springs. I suppose it is some kind of particle filter to prevent dirt in the rest of the injector.
This net was completely covered with some brown semi transparent stuff. Apparently the fuel can still pass it but I can't see how. This stuff is HARD. The ultra sonic cleaner could take some of it out but not all. Soaked in 5-56 for 24h didn't help one bit. I finally tried to scrape it off it with a small screwdriver. I still haven't got all of it off.


The high pressure itself does not keep the injector clean. The high pressure together with high flow keeps it clean. The very small hole in the washer was completely clean, as were the rest of the delicate parts. But the flow through the "filter", or what ever it is, is much lower.

Anybody got a guess what the brown stuff is and what could dissolve it?

When looking on the intake valves there is small but noticeable difference in color on them. Two look ok and two looks like they have been running slightly lean. Not saying this must be the injectors but it could be. In that case I might find another one with this dirt in it.
 

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Yes, they can be cleaned and tested by most shops that overhaul Diesel injectors. The have no similarity to modern electronic gasoline injectors, but are essentially the same as mechanical Diesel injectors.

Greg
 

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Discussion Starter #8
Ok so now I have taken all of them apart and only one had the "filter" clogged up.

I never really got it completely clean. But at least when I blow through it, it feels and sounds like the other three. So probably clean enough.

An interesting find though. Two of the other injectors had some dirt in the black part (furthest to the right) and the small part with the spring. I am not sure if it effected the performance of the injector but it was dirtier than expected.
This dirt was easily removed with the ultra sonic cleaner though.

Now I am just waiting for some valve shims. Then I can assemble the engine again and see if there's a difference.
 

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Yes, they can be cleaned and tested by most shops that overhaul Diesel injectors. The have no similarity to modern electronic gasoline injectors, but are essentially the same as mechanical Diesel injectors.
I tested and selected a bunch of Spica injectors to find the best ones for a Monty once. I used a Bosch injector tester used for Diesels (and early mechanical bosch injection systems used on Merceded Benzes in the '60s (a very poor system when compared to that of Spica)). I few hard blasts with the tester does seems to clean up the spray pattern on the good injectors. I have pulled the bad ones (that have an opening pressure lower than normal) apart and found the some of the internal springs broken.

From memory I read that the Autodelta cars that used the Spica pump used a Ford tractor sourced injector running at a lower pressure for lower parasitic losses.

And I also remember seeing a picture on this forum of a Spica injected car running K-Jet injectors (they operate at 5 bar - 75 psi) with plastic lines as per GTAMs. Looked great!
 

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Does anyone have suggestions for getting the washers and filter disk (not sure what its really called, but the one with the really small hole) out of the top section of the injector?

I got a spare set of injectors and am cleaning them out - everything else has gone fine but I can't get the stuff out of the top and dont want to just start pushing a rod through the top or anything to force them out.

Is there a trick?

Also, does anyone know the spec torque to tighten the sections back together?
 

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Discussion Starter #11 (Edited)
If I remember it correctly I had to whack it on a block of wood and also tap the washers from the inside with a small screwdriver to get them out. The filter however almost looked like it was part of the entire "housing" and not a separate dish that could be removed.

Be careful when disassembling the injector. Inside the black tube (far right in the first image) there is a VERY small brass piece. It is only a couple of mm big and very difficult to find if you drop it on the floor.
I did not know of that part when I took the pictures and therefor not shown in the pictures.
 

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The filter however almost looked like it was part of the entire "housing" and not a separate dish that could be removed.
They do come out, but I would not force them out. On the few "sacrificial" injectors I have rebuilt some of the times the filter screens simply fall out. I have found that if they don't want to come out its better to simply leave them in the assembly and soak them in carb cleaner overnight.

I have even contemplated whether or not its even necessary to have them in the injector assembly at all. Has anyone simply removed these from the injectors?
 

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Be careful when disassembling the injector. Inside the black tube (for right in the first image) there is a VERY small brass piece. It is only a couple of mm big and very difficult to find if you drop it on the floor.
I did not know of that part when I took the pictures and therefor not shown in the pictures.
What small part is this? Do you mean the nozzle end itself? So far I have not pressed on that to try and get it out on the ones I've taken apart, but have found no other parts inside other than what's in the photos.
 

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Take a look at the attached fuel injector diagram. There is a piece in the very bottom of the injector that comes out. It can be removed by compressed air, but be careful not to shoot it across your garage. Dont ask me how I know this. :oops:
 

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Splendid, thanks for the diagram!

Does the rest of that document give any specs for what the torques are supposed to be?

I find that the top sections are generally VERY tight when I've taken them apart. The lower part with the black section is not nearly as tight and from the way things fit together I don't think you want to cram the internal components too tightly.
 

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I picked up a couple sets of injectors for pretty cheap on ebay last week and have been experimenting with cleaning and testing them. I borrowed a diesel hand pump like the one described in the Spica maintenance manual and have done my best to follow the procedure:

D6 TESTING THE INJECTORS
Since the operating conditions of the injectors are not so heavy (being
located in the air intake ports and therefore not subject to the high pressures
and temperatures of the combustion chamber) and since the life of the
injectors is expected to be the same as that since the life of the injectors
is expected to be the same as that of the car, they should undergo a test
only when the cause for malfunctions is unquestionably attributed to the
injectors themselves.

To test the injectors use a handpump like that for testing Diesel injectors
but supplied with gasoline and provided with a pressure gage whose top dial
reading is 700 - 1000 psi (50 - 70 kg/cm²).

The procedure for checking the spray shape, injection pressure and leaks is
as follows:

- connect the test pump pipe to the injector inlet fitting which has a
12 x 1.5 mm metric thread.

- pump quickly to prime pump and injector.

- pump slowly until injector nozzle opens. This must take place at 360
400 psi (25 - 28 kg/cm²) for new injectors and at no less than 260 psi
(18 kg/cm²) for used injectors.

- again pumping slowly, bring the pressure to 15-30 psi (1 - 2 kg/cm²)
below the rating pressure taken as directed above and make sure that
there is no drip from the nozzle within five seconds.

- pump quickly and check that the spray is narrow, deeply plunging and
has good vaporization even at minimum delivery. At a distance of 4”
(100 mm) from the nozzle orifice, the spray cone diameter should be
about .8” (20 mm).

If the injector does not meet these requirements,
replace it with a new one.
What I found was that the set I had been running in the car was pretty bad. They had a reasonable spray pattern, but the pressure at which they opened was really different compared to each other - anywhere from 150psi to 325psi and none of them did a good job holding pressure (they would drip and the needle on the gauge would just fall to zero).

In all I have 16 injectors to work with and took them all apart, put the groups of parts through several sessions in an ultrasonic cleaner and then let them soak in carb cleaner overnight.

Re-assembling and testing them with the hand pump I found that there was variation in the thickness of the washers below the spring - some were very thin, some a little thicker, some had two thin, and a couple had a thin and thick. It seems clear that the washers are what's used to set how stiff the spring is and thus calibrate the pressure where they open.

The other key thing is how the assembled valve/spring piece matches with the surface inside the black nozzle. The condition of the valve/spring part seems to determine how consistently and at what pressure it sprays, but swapping them into different nozzles seems to change the shape of the spray as well as how well (or if) it holds the pressure.

In the first batch of testing my goal was to get a set of four that sprayed at a consistent PSI and held their pressure as well as possible. I made an effort to keep the needle and the part it fits in together but swapped the black parts and tried various washer combinations. In the end I did get a set that all fired right around 350psi and held their pressure at or above 200psi.

Now I'm going through the parts for the rest of them to see if I can find the right combination of parts to get a few more working properly to have on hand as spares… The service manual talks about how they should last the life of the car – but I think at this point the ones I had been using were past that and its been kind of fun to mess around with a bunch of them to try and get a set that works closer to the original spec.
 

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That looks similar to the tester I'm borrowing although their pump looks much heavier duty. I'm not sure either gauge they describe is ideal for us - the diesel one is for 3000PSI?!? and the gasoline one only goes to 100PSI.

The gauge I'm using now goes to 600PSI and is filled with glycerine. Initially it had a gauge that only went to 400PSI and was too springy to see accurately what the pressures were like while the injectors were spraying - the needle would just bounce around like crazy.

KR_Injector_Testing_01.jpg
 
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