Author Topic: Fuel injection systems  (Read 60704 times)

Offline Roger B

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Re: Fuel injection systems
« Reply #285 on: August 02, 2020, 07:51:18 AM »
Before I changed to milling mode I turned a pair of 10mm dia 15mm long aluminium spacers to fit the pump to the diesel crankcase. When I made the body I had not cut the recess for the element deep enough so the inlet port did not quite line up. I decided to take out the 0.5mm in the mill (it was originally done in the lathe). The body was centred and I bought the 8mm end mill into contact using the quill. The quill was then locked and the 0.5mm cut was taken using the Z feedscrew.
As I was in milling mode I cut the 3mm slot in the mounting plate for the rack adjuster. With an ER25 chuck and a 3mm short cutter you can't really see what is going on  ::)
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Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #286 on: August 05, 2020, 06:25:54 PM »
I put it all together for a trial fitting. Unfortunately due to a build up of tolerances there was a 1mm gap between the tappet roller and the cam  ::) As the Hobbymat was still in milling mode I was able to elongate the slots so everything lines up. The top spacer also fouls the locking grub screw for the tappet guide pin so I need to turn down the middle a bit.

Whilst looking for something else I discovered that the GM 5.7L diesel engines used a mushroom type injector. This was called a poppet injector and so far I have only found limited details. In one scanned copy of a GM service manual there is a poor quality drawing. Like the Lanz Bulldog injector it has a helical section to induce swirl in the fuel spray and seems to have a very shallow angle seating. I will have to ask some American colleagues if they can find me a discarded one I can dismantle and investigate.
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Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #287 on: September 01, 2020, 06:42:38 PM »
I fitted the new injection pump and after some effort primed it. Unfortunately I couldn't get any good results from the injectors  ::) I tried again with the test pump and got the same results  :headscratch: When I started up the horizontal engine with petrol injection it also did not run so well  :thinking:
I think that the brass body for the nozzle is not good enough. They work fine when initially lapped but are rapidly hammered or eroded. The first needle injectors had brass nozzles to deal with thermal expansion but I think that I need to try some stainless steel nozzle for better resistance. The needles/pintles are hardened and should not be a  problem.
Best regards

Roger

Offline Don1966

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Re: Fuel injection systems
« Reply #288 on: September 01, 2020, 07:09:21 PM »
I can say one thing about you Roger you are persistent. I been follow quietly and very interested in your thread. Have you tried a vain type fuel pump? Since Centrifugal force comes into play they make a good seal. The ones I am familiar with also have a relief valve since they are positive displacement pumps. Just me rambling.......


Regards Don

Offline Roger B

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Re: Fuel injection systems
« Reply #289 on: September 02, 2020, 05:22:35 PM »
Thank you for your interest Don  :ThumbsUp: I know there are a few people following in the background hoping I can make this work. I will keep trying, even if it doesn't work I have learnt a lot  ::)

I am aware of sliding vane pumps as vacuum pumps on our accelerator but don't know them as pressure pumps. I will have to do some research. As I have said before all comments and ideas are welcome, I am just making this up as I go along  :headscratch:
« Last Edit: September 02, 2020, 07:55:42 PM by Roger B »
Best regards

Roger

Offline Roger B

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Re: Fuel injection systems
« Reply #290 on: September 02, 2020, 08:02:14 PM »
I drilled the clearance holes and then drilled the seating bore 1.35mm and reamed it 1.40mm. The different needle depths between the new SS nozzle and the original brass one were interesting. The brass nozzle seating has sunk somewhat  :thinking:  Next I milled some spanner flats on the Proxxon. If the first trial is good I will try to find some 8mm SS hex bar. Now I need to lap the seating and put it all in the ultrasonic bath.
Best regards

Roger

Online Vixen

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Re: Fuel injection systems
« Reply #291 on: September 02, 2020, 08:25:47 PM »
Hello Roger,

You deserve a big prize for persistence.  :praise2:

That last photo showing the newly completed injector against the background drawing, suddenly brings meaning to all the machining operation photos. I guess that if you live in Switzerland, you are bound to pick up on then their watchmaking traditions.

Keep up the good work,  especially on the SU.

Mike
It is the journey that matters, not the destination

Offline steamer

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Re: Fuel injection systems
« Reply #292 on: September 02, 2020, 09:34:07 PM »
Looking good Roger!    Yes  you get a prize for persistence, that's for sure!

Dave
"Mister M'Andrew, don't you think steam spoils romance at sea?"
Damned ijjit!

Offline Roger B

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Re: Fuel injection systems
« Reply #293 on: September 23, 2020, 08:10:18 PM »
Thank you all for your support  :) This is very much a long term project  ::)

I lapped the valve into the nozzle with 1 micron diamond paste and gave the system a go on the test pump with alcohol. The pattern looks good without any individual jets. I hope to get a chance to try this injector on the diesel this weekend (supposed to be bad weather).
Best regards

Roger

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Re: Fuel injection systems
« Reply #294 on: September 23, 2020, 08:14:36 PM »
Ha ha. It's  the old psychological inkblot tests again.

Nice pattern :ThumbsUp:

Mike
It is the journey that matters, not the destination