Author Topic: Fuel injection systems  (Read 46367 times)

Offline Roger B

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Re: Fuel injection systems
« Reply #45 on: November 11, 2015, 07:36:25 PM »
Next attempt. I still have enough raw material for around 30 pump bodies so maybe one day I will get it right  :headscratch:

This time I finished the delivery valve pocket before drilling through with a new good quality 1.8mm drill. The hole depth is just over 20mm so not too far away from the 5d rule of thumb. It looks fairly central at the other end so I have some hope. I have started lapping and this time the 1.97 pin gauge passes through quite easily and the 1.98 still doesn't enter.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #46 on: November 15, 2015, 05:30:13 PM »
I finished lapping this body and gave it a try. It was difficult to get the air out of the pump until I found that the back fixing screw hole had just broken through into the pump bore  :facepalm:  :facepalm:  :facepalm: Time to start body number 4  :(

I have a set of diamond lapping paste syringes from RDG. I used the coarsest (40) for lapping the cylinders on my engines and the first pump body. I then realised that this may be too coarse and used 5 until I got to 1.97mm and then 1 to reach 1.98.

Once I got the pump cavity full with the same grade oil as I used in the last test the plunger was essentially solid. With the same weight on top it just sat there, probably taking around 10 mins to fall, so no video.

I then cleaned the oil out with some cooking alcohol (as used in spirit lamps) and tried with this alcohol as a fluid in this case the plunger sank in 3-4 seconds so it should work well enough with petrol as the require injection pressure is much lower.

I think that this body, in spite of my mistake, will be good enough to test an injector. So an injector here we come  :)
Best regards

Roger

Offline cfellows

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Re: Fuel injection systems
« Reply #47 on: November 15, 2015, 05:38:41 PM »
Hate having to redo things because of mistakes.  However, it happens to me much too often.

What did you use as a lapping tool?

Chuck
So many projects, so little time...

Offline Roger B

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Re: Fuel injection systems
« Reply #48 on: November 15, 2015, 06:15:08 PM »
I have plenty of 'trial' pieces   ::)  like many others on here I suspect   ;)

I'm using Acro needle eye laps for the fuel pump and injector. I also have some of their larger barrel laps that I have used for my cylinders.

http://acrolaps.com/index.htm



Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #49 on: November 22, 2015, 08:20:56 PM »
The next stage was to make a new D bit to cut the seat for the injector needle. This was a piece of 1.5mm silver steel (actually 1.49mm) lapped down to 1.45 mm. The 60 point was ground and polished with the Proxxon grinder held on the tool post. The flat was then filed and polished with the fixture I made and the end was hardened.

The needle was hardened before grinding, the point is 50 and the reduced section is 1 mm.
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #50 on: November 22, 2015, 08:32:42 PM »
The shank of the needle was lapped to 1.48mm and it was cut to length.

The spring adjusting screw and nozzle were made from a piece of 8mm brass rod threaded M8x1 for 20mm.  If (when  ::) )I make another nozzle I will cut the thread at the end. The spring adjuster was no problem, but the 0.35mm drill pulled out of it's holder (I'd tried soft soldering it in place). Luckily by tapping the end of the nozzle with a small hammer I was able to get the drill out  :)

This time I used Loctite to hold the drill in place and was able to drill the jet hole.

When I tried to put the parts together I found another problem  :( The D bit had opened the bore out to 1.48+ mm and the needle was already a running fit  :facepalm:

New D bit and nozzle time  ::)
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #51 on: November 24, 2015, 07:33:44 PM »
Found the problem  :) There was a little burr on the edge of the D bit (probably from the filing  :facepalm: ) that was enough to open out the hole the extra couple of hundredths. I carefully stoned the edges and made a quick trial hole. The 1.47 pin gauge wouldn't go in so just another nozzle to make  ::)
Best regards

Roger

Offline Don1966

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Re: Fuel injection systems
« Reply #52 on: November 25, 2015, 01:17:30 AM »
Cool Roger, I am still following you. I am really interested in how this turns out. It would be interesting to make an electrically solenoid version. I have even considered looking into making and electronic governor for these engines. I am still making steam engines but will be venturing into IC's later.

Don

Offline Roger B

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Re: Fuel injection systems
« Reply #53 on: November 25, 2015, 06:12:21 PM »
Thank you Don  :ThumbsUp: There are a few people following this little exercise, I hope I manage to make something that works but anyway I am learning a lot  :)

If you are looking at solenoid injectors this is some pretty amazing stuff:

http://www.f1-2000.co.uk/index.php?f=fuel_injectors

Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #54 on: November 28, 2015, 05:54:43 PM »
The new nozzle was machined more conventionally, cutting the thread (turning the lathe by hand) at the end. This time it all went smoothly including the 0.35mm hole and there is some material to lap out for the needle  :)
Best regards

Roger

Offline Don1966

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Re: Fuel injection systems
« Reply #55 on: November 28, 2015, 10:37:17 PM »
Hi Roger, have you ever thought of using a clock bushing for the nozzle orfice? They do make them in multi sizes. I use one on my mini propane burner. Time savers has them http://timesavers.com/search.html?q=Bushings&go=Search.


Don

Offline Roger B

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Re: Fuel injection systems
« Reply #56 on: November 29, 2015, 08:25:14 AM »
Thank you Don, I didn't know that such things existed   ::) I will have a look for European suppliers (I was surprised that the US ones were metric  :headscratch: are clocks generally metric?)
Best regards

Roger

Offline 10KPete

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Re: Fuel injection systems
« Reply #57 on: November 29, 2015, 09:56:24 AM »
Yep, generally metric.

Pete
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Offline Roger B

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Re: Fuel injection systems
« Reply #58 on: November 30, 2015, 08:19:37 PM »
Before I can lap the nozzle for the needle I need to drill the feed hole. I have been through many iterations of this design. The whole high pressure side of the system needs to the minimum number of sealing faces and the minimum number of places where air can be trapped. Rubber O rings are out as they will give too much under the pressure pulses.

In the end I went back to an earlier idea with a 60 cone directly in the side of the nozzle. As this is the same as a centre drill the cone and connecting hole could be drilled as one using the union nut as a guide. The union nut is turned from 8mm hex steel with an M5 x 0.5 thread and a 3.15 mm bore to suit the centre drill. The centre drill has a 0.8mm dia. tip.

I now need to make the brass nipple. I have some 1mm bore 2mm od copper tube for the connecting pipe.
Best regards

Roger

Offline Myrickman

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Re: Fuel injection systems
« Reply #59 on: November 30, 2015, 10:28:13 PM »
Roger, been quietly following along with great interest. Your perserverance in this challenge is admirable. All those teeny tiny bits and requiring such a high degree of precision....it will be so neat when you get it sorted out. I'm fascinated with your work. Paul