Supporting > Engine Ancillaries
Fuel Injection Systems Part 2
Roger B:
Thank you all for your support and interest :) This is, as I have said before, a long term project but I hope to be able to offer some solutions. A 12 cylinder version is just a lot of single cylinder versions :) The Porsche 917 pump was actually quite interesting. It had two rows of pumps with the rack down the middle so you needed plungers with left and right hand helixes.
Having finished the pinion and the end of the pump element I tried it with the return spring. A 1.2kg mass compressed the spring around halfway. Is that too much or too little :thinking: no idea, it will have to wait for some running trials. Next up I drilled the inlet port in the pump element and milled the locating flat. I did this using my home made fine feed for the little Proxxon drill. I could also have moved the vice over to the Proxxon mill which would also have kept the alignment.
The pump body is again made much as before using the 4 jaw independent chuck to give the offset. The final stage was a quick sanity check that the recess to locate the element was of the correct depth.
Dave Otto:
Still following along! :ThumbsUp:
Dave
Roger B:
Thank you Dave :)
Next up I moved to the small Proxxon tools and milled the cavity in the pinion for the tappet. The inlet hole in the body was finished with a 4.5mm endmill to give a flat bottom and the most threads for the inlet union. I used the small Proxxon drill to tap the M2 threads to attach the flange to the body and then moved onto the tappet. This is made from a short piece of 3mm keysteel so it can be hardened. The ends were shaped by filling rather than some complicated mill set up with rounding cutters and the centre was spotted from the pinion using a 4mm diameter centre drill.
The next steps are to harden and lap the element and to grind the helix in the plunger.
Roger B:
Next up is the pump mounting flange. There were several possible ways to make this however I decided to do most of the work in the lathe. It is fixed to the body with M2 countersunk screws. The final operations will be completed the next time I'm in milling mode.
Roger B:
The flange was milled to width and then profiled with some filing buttons. Next the slot for the control rack was milled with a 5mm endmill and then opened up to 6mm to be a closed fit on the rack.
A 30mm piece of the rack was cut to approximate size with a hacksaw and finished by milling.
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