Mery Engine fuel system question

[JBM3M]

 
This is the second Mery Engine I have built from Martin Models castings.  The first one would run for 30 seconds tops and quit.  Sold it out of frustration.  But I think now after a couple years of thought; how does it get air mixed with the fuel?  I was not giving any air and thus the thing would run after a spell of not running and then quit, flooded I assume.

Well I have reached the same point.  Built the Jerry Howell demand valve which is a type of demand that is suction from the engine.  This is a very low compression engine BTW.  So if one introduces an air jet or ? for air it will kill the suction on the demand for the propane.  I at a total loss how to resolve this, but I see photos of someone elses Mery and it appears it has an air intake after the demand valve. 

Still have to setup the ignition timing so am a bit away from completing the fuel system.  The demand valve is ready to go, but have to complete the fuel lines to the explosion chambers, so I think this is the time to address this issue.  Hopefully a successful Mery owner will have my answer?   

[Dave Otto]

You need to meter the air as well as the propane, the mix is very critical, so touchy to adjust and get correct. I will get a video and photos of my friends engine sometime this week, his engines runs great!
He has built separate fuel and air adjustments into the mixer. He also uses a demand valve which is most likely very similar to Jerry's design.

Dave

[JBM3M]

Is your friend local to Boise?  I live in Nampa.

[Chipmaster]

Hi JBM3M,

I began building a Mery Explosive a couple of months ago so I'm keen to see how your gas/air intake turns out.   

Andy

[Alyn Foundry]

No IC engine runs solely on fuel. We need a percentage of air mixed accurately for each cylinder charge. petrol/gasoline is pretty flexible but Propane and Butane are quite particular about the ratios. The Mery is normally aspirated and if set to run at a particular speed should not need any form of demand type gas valve. However from a safety aspect that type of control valve is useful should the engine stop for any reason.

For Propane fuelled systems a high quality adjustable regulator is recommended. And for fine control a secondary needle type of valve placed as near to the intake as possible will help immensely.

My own technique for setting up gas, gas engines is to use the burning flame method. By holding a taper or flame near the exhaust pipe and watching the exhaust burn. If you get bursts of Yellow then the mixture is way too rich. You’re looking for a nice, Bunsen Blue ! 😉

   Graham.

[JBM3M]

Graham, if you have link or suggestions for a regulator such as you mentioned? 

[Alyn Foundry]

Graham, if you have link or suggestions for a regulator such as you mentioned?

Try this one.

https://www.gasproducts.co.uk/cavagna-high-pressure-adjustable-propane-regulator-0-5-to-4-bar.html

Alternatively depending upon your location, any precision pressure variable regulator should work. It should be noted that bottled gas pressures vary depending upon both temperature and barometric pressure….😉

   Graham.

[Chipmaster]

I have satisfactory results running my Alyn Foundry engines using Cadac regulators on Coleman C500 cartridges their output is 30mbar, about 0.4psi.

Andy

[Dave Otto]

Is your friend local to Boise?  I live in Nampa.

Yup, we are both in Boise.
I just uploaded a video of his engine that I took yesterday.
<a href="https://www.youtube.com/watch?v=hW52BFZACbo" target="_blank">http://www.youtube.com/watch?v=hW52BFZACbo</a>

Dave

[Chipmaster]

Magnificent, such a steady and smooth running engine.

Thanks for uploading the video.

Andy

[Dave Otto]

The counter weights on the crankshaft make a huge difference.

Thanks,
Dave

[JBM3M]

The counter weights on the crankshaft make a huge difference.

Thanks,
Dave

I didn't oversize this time, so we shall see.  Would dearly love to speak/meet with this gentleman.  Would like to see his fuel setup, not quite visible enough in the video.  Damn she runs smooth.

[JBM3M]

I could add counter weights to the crankshaft, machine up a couple out of lead if need be.  Got a ways to go to worry about that.