Fuel Injection Systems Part 2

[CI]

Following along with interest....
 

[Roger B]

Thank you both 

Next a 30mm length of MOD 0.4 rack was milled to size and the corresponding slot was cut in the pump body. A quick check showed reasonable mesh with the control gear.

The pump mounting flange was turned from a piece of 30mm diameter aluminium. The previous version was made from a rectangular block of aluminium, both have advantages and disadvantages for marking out and workholding.

The thin slice was supported with a piece of 6mm silver steel held in the tailstock chuck for finishing the other side.

[Roger B]

It was then moved to the RT in the Proxxon mill to drill the fixing holes and machine the two flats follow by a quick fitting check on the engine.

[AlexS]

Per had a good comment. Borrow high speed camera.

https://kulturbuero.ch/zh/mieten/canon-eos-r6-2 ?

40 pictures a second or 120p 4K or 180p Full HD

[Roger B]

Thank you Alex. At the moment I think I can see where the spray problem is using a piece of white paper. The problem is more how to modify the nozzle to get an even distribution of droplets and not a selection of different sized blobs.

Next the fixing holes for the body were coordinate drilled, referenced to the bore and one milled edge. With the previous version that was made from a rectangular block these holes could just be marked out from the edges. These holes were spotted through to the body and drilled and tapped M2.

Next the base was profiled, as before, using some 6mm filing buttons. Finally I turned a thin wall bronze bush and pressed it in, followed by reaming 5mm again.

I will now move back to the Junkers thread to finish and assemble the injection cam and rocker.

https://www.modelenginemaker.com/index.php/topic,8690.405.html

[Roger B]

The next step was to harden and lap the pump element. I ran the 1.95mm reamer through by hand to remove any burrs caused by drilling the inlet port, then heated the pump element up to a light orange, kept it there for about a minute and dropped it into a water bath. As expected, the 1.95mm pin gauge would no longer go in so I started lapping with 5 micron diamond paste and an Acro Needle Lap.

https://youtube.com/shorts/Gice8kHvOQI?feature=share

<a href="https://www.youtube.com/watch?v=Gice8kHvOQI" target="_blank">http://www.youtube.com/watch?v=Gice8kHvOQI</a>

When the 1.95mm pin gauge would go through I changed to 1 micron paste and continued until the 1.97mm pin gauge would just go through.

I already had a 1.97mm helix, (I usually make them in pairs one from each end of a pin gauge. The procedure is in post 12 of this thread.) which fitted nicely into the bore 

[Roger B]

The parts were cleaned in a ultrasonic bath to remove the diamond paste residue.

I then checked the required plunger length once again and cut the plunger to length with an abrasive disc. The non-helix end was then annealed, whilst held in some large pliers to act as a heatsink, and threaded M2.

After a couple more checks the tappet was fixed to the plunger with Loctite.

[Roger B]

Next up was the delivery valve. This could be modified from a commercial union but I started with a length of 6 mm brass hex. The union end was made first, using a 2mm centre drill to cut the cone. The other end was drilled 3.2mm to give clearance for the 3mm ball and the tip was turned down to 4.4mm diameter for a length of 1 mm to make the sealing face.

The ball valve seating in the pump element was then lapped with a 3mm diamond ball lap ready for a trial assembly. I first checked the fit of the plunger in the pump element and control gear. This tended to jam so I put the element in the lathe to polish the spigot that the gear runs on. It was bent     I guess it distorted during heat treatment    I was able to straighten it to an extent using the end of a lathe tool shank to apply controlled pressure with the cross slide. The rest of the assembly was ok and the fuel rack moved quite smoothly.

The fuel inlet is a standard Regner M5 x 0.5 union.

[Roger B]

And on the engine