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Injection lever modification
This is the most important part, but also the most difficult one. You must be able to weld pieces of small metal 2mm thick… a MIG is good enough.
Image 4
The pump sleeve is pointed by the red arrow. The more this sleeve is moved upwards, the more fuel the pumps inject. With a tdi camplate (in top of the yellow arrow), the plunger moves very quickly to the top (the camplate bumps are very sharp, abrupt) whereas for an indirect injection camplate, the plunger moves slower to the top (less abrupt bumps). The fact of having abrupt bumps thus decreases the time of injection… this is one of the principal advantages of a DIRECT injection over an indirect one.
Saying that diesel is incompressible, is not completely true with pressures as high as those that one finds in an injection pump. When the plunger moves quickly to the top, the time of injection is shorter, but for the same sleeve position the injection quantity is lower with a tdi camplate than with a td camplate. This is due to the increased delay of injection with a tdi camplate between the beginning of the rise of the camplate on the rollers VS the injection of a diesel fume. It is also the reason for which the static advance must slightly be increased as the camplates become more abrupt. (0.95mm td, 1mm 1Z tdi, 1.05mm ALH).
The sleeve which regulates the injection quantity moves approximately 1.6mm in an AAZ pump and 2.6mm in a tdi-e pump. One must thus modify the pump to get on more 1mm of up/down play. It will thus be necessary to be VERY precise. In fact, you can have 2.6, 2.8, 3.2 mm, but if you are 2mm decentred you will get nowhere… the injection quantity screw will be at the maximum and the injection will be minuscule…. Or the injection quantity will be at the minimum and the idle will be 2000RPM.
What makes the sleeve move is the lever beside (at the left) the blue arrow. The vertical play allowed by this lever must be lengthened. To do so, one will lengthen the distance between the lever axis and the pin that is inserted inside the plunger sleeve. But as we are limited in what we can do (~5mm more) one will have to also lengthen the lever pointed by the green arrow of image 5.
Image 5
Why don’t we only lengthen the lever pointed by the green arrow? Because the lever of image 4 is also used to control the idle by the help of the governor. If this lever is not lengthened, the governor will not be able to make the sleeve move enough to keep a regular idle.
Lengthen the lever pointed by the green arrow of image 5 to 13mm - 14mm between the middle of the two axis. Carefully keep the same angle so that the lever will not rub in the pump cover. Cut it with a hand saw. Take a small metal peice, a MIG and go!
Principal lever modificationImage 6
The goal is to lengthen the distance between the axis of pivot (line red) and the pin(yellow line) which fits in the sleeve (at the end of the green line). In other words, one wants to increase the distance between the yellow and red lines. You will then cut the metal end at the end of the green line which holds the pin. Thereafter, one will further weld back this pine farther away ~5mm from the axis (indicated by the red line). This way when the lever moves, the pine chrome which fits in the sleeve of hydraulic head will traval more.
However, if you move away the pin, you will have to modify ALL the lever. If you don’t, you will bent the hydraulic head plunger. To avoid bending, decentring the pin, putting the pin too high or too low of 1 or 2mm, putting the pin too much to the left or to the right, etc one must make a gabarit (some kind of template) with an unmodified 1.9td lever. Make threads in your cabarit to hold your lever COMPLETELY as if it were in your pump at a given injection quantity position. IMPORTANT, when it is screwed NOTHING can move: the pin cannot move up and down and the 2 parts of the lever cannot move. Use an old hydraulic 9mm head from an AAZ pump and weld the plunger onto a plate. Also weld the sleeve on plunger, and put a system to lock the lever in the same position everytime. NOTHING must move and when you put it back, it is in the same position.
Step 1To reassembled ALL the lever, there is no choice but to make another hole lower; i.e. between the hole of the retaining screws and lever axis. The bore is 5mm diameter and there is approximately 7mm of space. You thus do not have any room for play between the 2. Put the hole in the center. Image 7 allows to see that you will have a play from left to right… green circle VS purple circle. If you drill in the green direction, you will have to remove shims behind the governor (toothed wheel). If you drill on the purple side, you will need to add shims behind the governor. Try to bore in the center, but ESPECIALLY ensure that you drill equally on the 2 sides (so the lever is not twisted). To use a with cement drill bit 5mm diameter (do not make it turn too fast) if it is too difficult to bore.
Image 7
Once you made the holes, put the lever back in the pump –using the new holes- without the hydraulic head installed and ensure that the whole lever moves correctly. You may have to grind a little the end of the retaining screws who will surely rub on the lever.
Step 2Put your lever in your gabarit and weld the pin to the same exact configuration as before..but ~5mm away. It must be EXACTLY at the same position as before: left, right, and especially up and down, but 5mm further (I say 5mm but that depends from where you have to bore, it can be 5.3mm, 5.2mm, 5.4.. etc).
WARNING: If you bored 5mm higher and you welded the pin only 5.4mm away, your pin will be 0.4mm too far. It will then push on the hydraulic head which may bent. Ensure to have the same depth of insertion of the pin with your modified and original lever. To avoid going too far, I built my gabarit by putting the pin of the original lever COMPLETELY at the bottom of the hole of the sleeve.
Step 3Since you upped your lever of ~5mm, it will rub in your pump cover. You must then remove 5mm at 2 places. The first place is indicated by the blue line of image 6. You cut it and that’s all!!
The second place is indicated by the purple line of image 7. You must weld it back though. This part of the lever is in fact the place where the bolt allowing to adjust the injection quantity is pressing. You must weld it back precisely using your gabarit. Also, weld it just enough to hold it. Put the lever back in place in the pump, with the cover on and put grease at the end of the injection quantity bolt. You should see the place of contact by a trace of grease on the lever.
Once again, use the gabarit to weld it to the good position. If you do not weld this axis at the good place, your adjusting bolt will be too long or too short.
Gabarit modificationsIf you think that your adjusting bolt is too long or too short, that you do not have enough or too much fuel injected, you can modify the position of the lever pin so that it is in the direction + fuel or – fuel by modifying your gabarit. Put an adjustment screw on you gabarit to hold the lever in place. This way you will be able to unsolder your lever pin and adjust it as you like.