Two Cylinder Engine

[Roger B]

It's getting there 

I had to drill and tap a new grub screw hole in the sector as the original was inaccessible. Some trials suggested a suitable profile which I filed on the sector and then added a return spring to the rack. The first trials were good so I set up a quick load trial. The load is a resistance back with a maximum load of 1 ohm. This means I just need to measure the current and square it to get the output in Watts. The meter has a full scale of 15A. I was able to run up to 9A so 81W and could both accelerate under load and add and remove the load without stalling  The video is a bit messy but hopefully you can see what is going on 

<a href="https://www.youtube.com/watch?v=7RVp_fwLo0o" target="_blank">http://www.youtube.com/watch?v=7RVp_fwLo0o</a>

[Kim]

That is very cool, Roger! 

81W seems pretty respectable for a little fuel-injected engine!

Kim

[Roger B]

Thank you  I think the real output is somewhat higher but I can't measure it at this time 

[Roger B]

As the MFA motor was not capable of fully loading the engine I found another motor in my 'rescue' collection that will hopefully have a more suitable characteristic. Some quick trials showed that this was not quite capable of starting the engine on 12V and due to the larger diameter I decided to mount it on the end of the existing MFA motor and hanging off the end of the baseboard. The coupling I have has a 1/4" bore both ends which suits the MFA motor. The new motor has a 6mm shaft so I needed to bore and sleeve the coupling. With some thought I bored and reamed it out to 11.5 mm as I had a suitable reamer and I can then turn a piece of 12mm stock to suit. I drilled the grub screw hole in the sleeve to 6mm as clearance so both parts would be held by one grub screw and I didn't need Loctite (experience says this will be changed more than once  ). I now see why Jason choose 24mm bore as he can use 25mm stock for the pistons rather than turning 30mm down to 25mm.
The mounting plate was clamped to the face plate ( Dodgy Set Ups are Us) drilled 13.5 mm and then bored 28mm to suit the motor.

[Kim]

Silly question, but what does MFA mean here?

Thanks,
Kim

[Roger B]

Kim, not a silly question, just a European one. MFA is a supplier of model drills, motors, gearboxes, etc.

https://www.mfacomo.com/index.html

I have tried to use available motors as my loads rather than random things I have in my rescue box so others can hopefully follow/copy.

[Kim]

Ah, Thanks Roger!  That clears it up for me.

Kim

[Roger B]

The fixing holes were drilled in the plate and the support arms were drilled and tapped M5. It was all then assembled and set up for a quick test.  The characteristics of this motor/generator are completely different. I was getting around 60V at full speed without a load and around 30V at 3A on load but then the engine started spluttering and stalling, it would idle but not rev. I tried adjusting the fuel rack setting but without success  Removing the timing gear cover showed the problem, lots of brass/oil emulsion and a completely worn excentric strap 

[Roger B]

Brass was obviously not a suitable strap material for the speed/load requirements of this injection pump. The excentric on the horizontal engine injection pump shows no signs of wear after significant running, but it barely reaches 2000 rpm whereas this one will exceed 8000 rpm.
I decided to try a case hardened steel version together with case hardening the excentric. This was roughed out of 2mm strip with a hacksaw, rounded on the Proxxon mill and cleaned up with some filling. It was bored directly from 6mm by taking shallow radial cuts. I was doubtful about opening it out with a 12mm drill first due to the risk of snatching. I am using the 4 jaw SC chuck as that was on the lathe at the time.
After hardening and cleaning up it seemed to run freely so I reassembled the engine and gave a quick trial. It runs again  however I need to readjust the rack/throttle relationship.

[crueby]

Hi Roger,
Are the two pieces different types of steel? If the same, is there a risk of the two galling together, or does the hardening prevent that issue?
 
Chris

[john mills]

Hi
I worked in industry on metal working machines as apprentices we were told you don't run similar metals together but wire bending machines were all driven by cam rollers and pins same hardened and ground some nitrided slides were lined with ground stock hardened and ground all sliding faces only one had a free loading bush of aluminium bronze as long as lubrication kept working gave good service if lubrication failed then turning blue and wearing away when they stopped turning.
John

[Roger B]

I believe that both hardened steel and cast iron don't tend to gall when run together.
The highest loading in a conventional IC engine is the camshaft - cam follower interface. These are almost always surface hardened steels however without adequate lubrication they will rapidly fail. A number of the additives in 'High Performance' motor oils are to help this interface.

[Roger B]

I'm still battling with this one    It ran very well and smoothly as can be seen in the various video clips but then started giving all sorts of problems. At first I thought it was the wear in the injection excentric but after having fixed that it still kept misfiring and stopping. I could hear little ticking noises just before it stopped and realised it was tracking in the distributor cap.

I removed the cap and found it full of gunge so I cleaned it and reassembled it. It still wouldn't run well and was sparking in various odd places 

This engine has a 6V coil (because that's what I had) fed via a 7806 6V regulator from the 12V battery. This worked ok on the horizontal engine although I also had problems with the regulator there. I checked the voltage on the coil, 12V with the points open 2.6V with the points closed. The regulator had obviously failed 

I replaced the regulator and it seemed to run better but with an odd 'note'. This was due to a crack in the exhaust manifold cause by the vibration  I silver soldered across the crack which hopefully also anneals that area of the manifold.

Finally I was ready to try it powering a little electric car I had made for my children many years ago. The traction batteries were disconnected and the controller was connected to the output of the generator. The engine was started and I cautiously pressed the accelerator. It would move slowly under engine power  but the running of the engine became worse and worse. As the lighting in our underground garage is fairly dim I could see the fireworks in the distributor cap so assuming the regulator had failed again I gave up for the moment.

<a href="https://www.youtube.com/watch?v=y4ZTvBWlS4s" target="_blank">http://www.youtube.com/watch?v=y4ZTvBWlS4s</a>

Back in the workshop a quick measurement showed 12V on the coil again so this time I will do it properly and buy a 12V motorbike coil like I am using on the horizontal engine now.

[Kim]

Good detective work, Roger.

Bummer about the regulator though... Wonder if the 7806 is getting high-frequency current spikes or something and causing it to fail?  Would the 12V coil help that?  Bigger inductor to filter out the high-frequency spikes maybe?  (he says making it up as he goes along.)

I'm sure you'll get it figured out but it's a struggle, nevertheless.

Kim

[Admiral_dk]

I don't really see many standard Regulators that can survive in this application .... (not even all Lab Supplies can).

Serveral reasons (and Kim mentioned some of them) - The Ignition Coils often requires more Current than the god old 7806 (and it's siblings) can supply, they are not happy with high voltages or reverse polarity - some of this can be 'Rectified' with Diodes and Condensators ....

None the Less - Great that you found the reason     

Per