Getting The Injection System Done And Making It Run.
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28 May 2018:
Well, in response to a numerous request, here is a video of the naphtha combustion test I did this morning.
 Here's the link:
In case you're interested, the motor is running the engine at about 600 RPM.

Now, while motoring the engine, I will stufy the Lombardini injection pump sent to me by Doc.  I hope I can use some of it on this engine because it has the helix on the plunger to control the amount of fuel delivered.  This would be the easiest way to get the job done.  I will still have to come=up with the injector.

The Lombardini injector on the left, pump on right..
I'd like to use the injector, too but it's way too big to fit on this little engine.
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29 May 2018:
I took the Lambordini pump apart and think that I can make my own housing so it will be small enough to mount on the engine.
 
            Disassembled pump.                                                          The rusted spring in the outlet valve.

Here is a drawing of the important parts of the pump.
As you can see in the right-hand photo above, the pump got some water into it's outlet and rusted the delivery valve spring in two.  I'll see if I can get a replacement.  If anyone out there has one, it would be nice to have it.  I think the engine is a Model 6LD435 or 6LD435A.  I looked in the injection system specifications and the injector cracking pressure should be set between 2,755 PSI and 3,055 PSI, a lot higher than I plan for my injector so the internal pump parts should work fine on my engine.  Delivery volume could be too high but I think I can compensate by setting the stroke of the pump shorter or simply changing the amount the plunger can turn between full power and cut-off.   
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3 June 2018:
I thought I'd report on progress on the pump.  I've been working on CAD while doing yard work, etc. and think I am close to turning good metal into chips and scrap.

Design for the new pump.
I will mount the pump as an outrigger at the end of the camshaft.  I sure hope I get this right because it is a pain to re-engineer it.  With a little more design work to do, I will soon back in the shop.
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5 June 2018:
Here is the mount for the injection pump.

Injection pump mounting bracket.

The mount was made from a piece of 2" X 4" X 1/4" steel tube.  Whittling it to shape took a while.
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6 June 2018:
The pump housing is made and I think it will work.

The pump housing minus guts for now.
Tomorrow, time permitting, I will get the top cap for the pump done so I can assemble it.  When the cam follower is done, I can make the final measurements for the cam.  The linkage from the governor is going to be a bit on the Mickey Mouse side but it should work.  It will be a bit springy but that ought to allow the lever on the pump to be shoved to the cut-off position to stop the engine.  I'm interested to see how much the pump leaks through the plunger/barrel clearance.  There are no seals on this pump and Lombardini says that, if the engine oil level rises from Diesel fuel leakage, it's time to replace the pump.
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7 June 2018:
The top of the injector is almost done.

Injector top being test fitted.
Since I didn't have any L-10 steel of the right size and didn't want to turn down a really BIG round, I resorted to brass.  Expensive, but easy to machine.  What's left on it is to mill four flats for a 3/4" wrench.
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8 June 2018:
I really wanted to put a 7/8" hex on the top of the pump but don't have a collet that fits into a hex housing to do just that.  Shazam!  I came up with a neat way to get the job done.
 
Making the hex on the valve housing.

Since the outlet fitting has a nice hex on it, I decided to use it as an indexing tool.  As you can see, I used a 6-point semi box end wrench to locate the housing, making sure to take the slop out of the wrench to fitting fit.  The major diameter is 1" so, for the first three flats, I took off 0.0625".  Then, using the first three flats for references, I then set the mill to remove 0.125" from the remaining three flats.  I must say this was a brilliant move on my part.  A close inspection of the "nut" shows no difference in the slight O.D. between the ends of the flats.

I'd rather be lucky than good!

Here's the pump ready for the fiddly bits.
I've got some filing and fitting to do to get the fuel control lever to completely cut-off the fuel.  There was an eccentric in the original housing that worked on the barrel, rotating it a little each way and I think it was used during assembly to set the cut off.  When I built my housing, I used a simple 4-40 screw to locate the barrel.  What I have to do now is to file a little off of the bracket so the lever will move far enough toward cutoff to stop fuel output.

Oh, yes, that IS a screw starter between the camshaft and the follower.  It is there as a temporary prop to keep the follower from falling off.  Note that I've added a bleeder screw just this side of the fuel inlet barb.

When I assembled the pump this time, I left the delivery valve poppet out so I can determine the start of fueling.  Once I get the cutoff lever filed to where I want it, I will attach a fuel tank to the pump, bleed it and measure the actual position of the follower at the start of delivery.  Then I will determine the maximum fuel point and measure the follower position again.  These measurements will give me the information I will need to make the cam that drives the pump.  Now, since I've never done this before, I may find some "aw-shoots" but that's part of the learnin' process.
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9 June 2018:
The measurements are done and the cam will have a rise of 0.060 for full fueling.

Here's the setup for measuring start of delivery and max fuel.
The pump cam will have a major diameter (end of delivery) of 1.990" and a minor diameter (start of delivery) of 1.870".  This allows about 0.020" extra for overtravel.  It's designed to have the follower a few degrees into the ramp before fueling starts.

I've also substituted a lighter plunger spring for the stock one because I need to minimize load on the un-hardened cam.  If it's too weak, engine speed will be limited.

The cam should be done tomorrow and I will then motor the engine to make sure all works.  I have to keep in mind that this pump may not work due to the fact that it is for a the larger Lombardini 6LD435 engine that has a displacement of 26.6 cubic inches as opposed to the 2.48 cubic inch volume of my engine.  This makes the pump about 10.7 times too big.  Because of this, I have some doubts that delivery can be throttled back enough.  We'll see.

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10 June 2018:
Got the cam made but something went wrong with the dimensions.  I put it all together and the pump doesn't pump.  I think the pump stroke is wrong.  I'll take some time off of the project and try to winkle out what's the matter. 
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12 June 2018:
Back on the job.  I got the pump figured out.  I had the pump plunger too high by about 0.050".  Once I lowered it by that amount, it started pumping just fine.

Then, I started-in again on the injector.  So far, I've still got a lot of dribbles and side squirts.  Changed the poppet angle to around 15 degrees and am now in the process of getting the valve lapped-in again.  Tomorrow, we may see a spray but I wouldn't hold my breath.  Got some fiddling with springs to do.

The latest iteration of the injector.
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15 June 2018:
Well, today, I got the injector poppet lapped until it made a "sort-of" acceptable spray.
 
            The injector tip.                                                           The injector installed on the engine.
I got it all on and decided to give it a spin to see if it would make smoke.  I got the camera going and motored it then increased the fuel.  Nothing happened except that the gasket on the injector to head joint blew.  Then the intake valve stuck from interference with the injector so off came the head for a bit of a re-work.

I was using the body from the original test injector and hoped that it would seal on the threads.  Not!  Even a gasket didn't help.  I will make a new bottom half of the injector, this time with a flange so I can use a copper washer.  Also, the previous injector was about 0.100" short.

Since the engine didn't fire, I deleted the video.   I'll try again when I get things fixed.
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17 June 2018:
Back at it today, I did some CAD on the injector.

The new injector design.
This design uses the top of the previous injector, modified for length and a different fuel line fitting arrangement.  That and the copper gasket washers are what I got done aside from the CAD today.  Not shown in the drawing is the spring that holds the poppet shut.

I've decided to go with a 10 degree seat and 15 degree valve face on the poppet.  This will make it easier to lap it to fit.  I may try to make the head of the valve by heating it and hammering a rough shape, then machining the face.  The previous poppet was two piece, peened into place on the stem.  That was really difficult to make because it is so small.  The body and valve are all that is left to make.

The injector shaft is threaded 12-24 and screws into the head with a copper sealing washer.

A follower of this page says that I should be careful to not let the injector get trapped in the head by carbon build-up in the threads.  After it is debugged, I will apply some anti-seize compound to the threads.  That should help the situation.  I've had that problem with The Homebrew Hvid explosion cup getting stuck due to carbon build-up.
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18 June 2018:
FIRST SMOKE!  
Nothing too much to brag about but the engine did make smoke (lots of it!) and sounded like it was running although I didn't take it off the belt.
   
    The latest injector.                                                                            Making smoke!
As you can see, it made smoke and stunk-up the shop.  It would only run with the fuel almost all the way on and didn't make enough power for me to try taking it off the belt.  Also, it appeared to blow a lot of unburned fuel past the rings, an indication of poor spray pattern.
Who IS that old bald headed guy in the flick??

Along with finishing the injector, I raised the compression to the maximum (without making more shims).  I will re-visit the injector tomorrow.  Once it is running fairly well, I will hook up the governor and make a cooling system.  I think I've got a small piece of air conditioner condenser left up in the attic to make it out of.
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19 June 2018:
I found one reason the engine didn't run well and smoked.

Poppet pushed back into it's guide.
As you can see, the poppet had been blown back into the bore of the injector.  No wonder it was flakey.  The reason this happened is that I made the previous poppet head too small.  In any case, I didn't like the way heating and peening a head on the drill rod worked, distorting it at the head end.  My solution was to use my Dremel toolpost grinder to turn the 0.069" drill rod down to 0.048" at the end then, using some 0.125" drill rod, making the head, drilling it to just fit over the turned end of the stem.  The head was slipped over the turned area and the stem was peened to hold the head firmly in place.
   
        Head on stem ready for peening.                               Peening the head of the injector poppet                                  Grinding the 15 degree face on the poppet.
Note the home-made collet to hold the poppet stem in while working on it.  Not seen is the split that is sawn parallel to the bore of the "collet" to allow it to clamp the drill rod in place.  Using the Dremel as a toolpost grinder is all right except that it doesn't give a really fine finish on small parts, making it necessary to spend the better part of the morning lapping it to fit and seal in the injector body.

When the poppet was finished, shims were added to the spring to get the cracking pressure up to around 1,200 PSI.  Although nothing to write home about, the spray was finer.  After putting the injector back on the engine, the timing was retarded to about 10 degrees ATDC and it was motored and, using the heat gun for a minute or so, it started firing.  Not wanting to run it long enough to overheat, I did find that it runs better and, at the end of the short run, I flipped the belt off and the engine continued to run for a few seconds but finally slowed and stopped.  I think that with an hour or so of constant run time, the compression will rise and it will run better.  The goal is to be able to crank start it and have it run reliably.  

Core for the radiator.
I went up to the attic and found the remainder of the air conditioner condenser coil.  I will use it for a radiator which is next on my list.  Once that is done, I will hook-up the governor, make an adapter for the outside exhaust and will then be able to run it without stinking up the shop too much.  It is hot and humid here in the Panhandle of Florida and, yesterday, I turned off the air conditioner, raised windows and ran a fan to clear out the smoke.  During that short time, the ways on the lathe and table on the mill got a haze of rust from condensation.  Not good!

It will probably be a few days until I post again.  Maybe by that time, I will have it running with the outside exhaust and will make another video of it as it progresses to a show ready engine.   
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Boy!  This is fun!

In case you see me about to do something really stupid and want to warn me, here's my email address
[email protected]
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