Model Engine Maker

Help! => Specific Engine Help => Topic started by: MIKETANGO on September 02, 2014, 04:16:24 PM

Post by: MIKETANGO on September 02, 2014, 04:16:24 PM
Hi everbody, I have recently converted my Wyvern to run on Propane gas having tried Petrol and Methanol with no success. Does anyone know what cylinder pressure (compression Ratio) I can expect, at the moment I get about 65 PSI?? It runs okay with the starter motor engaged however when disengaged slows down and stop within a 2-3 seconds. Carb. set at 1/4 turn from off for petrol, propane set at about 1 PSI ( a Hiss).Is there anyone out there who actually is beyond my stage and have a successful running Wyvern???
Regards to all
Title: Re: WYVERN
Post by: MIKETANGO on October 19, 2014, 04:50:50 PM
Wednesday 15th October I ran the Wyvern for 5 minutes on Propane (1/2 turn out on the demand regulator valve) with the original carburetor. I had increased the compression to 75 PSI by fitting closer tolerance fit aluminum  piston (1 1/2 thou). Having blown the gasket, will try a copper one and try running on petrol.
Title: Re: WYVERN
Post by: Roger B on October 19, 2014, 05:42:33 PM
Congratulations on getting a run  :ThumbsUp:  :ThumbsUp: What were you using for the original gasket?
Title: Re: WYVERN
Post by: MIKETANGO on October 19, 2014, 06:12:40 PM
Klingersil c4430. I suspected it blew because of pre ignition on re starting with a hot engine? Lesson learnt here, SHUT the fuel OFF to stop the engine!
Title: Re: WYVERN
Post by: Rustkolector on October 21, 2014, 04:18:09 AM
Propane has a few quirks. You should be using a demand regulator (Google demand regulator or zero governor) in your fuel system. It only allows fuel flow to the carb when there is a vacuum signal from the carb venturi. Putting positive pressure on the carb fuel inlet makes operation more difficult and unsafe. Fuel pressure to the demand regulator only needs to be about 4Ē of water column for good operation. Higher pressures will not provide any benefit. A gasoline carb will only need another turn or two open to run with propane and a demand regulator. A self-compensating carb will throttle pretty well on propane. A non-compensating single jet gasoline carb will not throttle well on propane. With the latter, a change in needle valve setting will probably be required whenever an engine speed is changed, but the Wyvern is a constant speed engine so this is of no consequence.

On a model engine, propane is not at all fussy about compression ratio. I usually run about 4.5:1 for slow speed operation. Slower speeds with the Wyvern on higher compression ratios will require much heavier flywheel rim mass. I canít comment on your head gasket failure, but lower compression might help.
Title: Re: WYVERN
Post by: MIKETANGO on October 26, 2014, 12:40:55 PM
  :pinkelephant: Hi All, Just finished a test run and here is a video to watch and enjoy XWvBCqZqCZEfeature=youtube_gdata
Title: Re: WYVERN
Post by: tangler on October 26, 2014, 01:18:29 PM

Nice One.   :ThumbsUp:

Slow running is good.  So, did you use the carb as drawn?  If so, are you using the petrol or gas jet?

Anyway, I'd like to get mine to run like that.

Thanks for sharing,

Title: Re: WYVERN
Post by: Kim on October 26, 2014, 03:13:16 PM
Congratulations Mike,
Looks like your conversion was a complete success!  Very nicely done.
Thanks for sharing the video!
Title: Re: WYVERN
Post by: Don1966 on October 26, 2014, 03:19:36 PM
Very well done Mike and a great runner. I especially liked the  video production sequence.............. :ThumbsUp:

Title: Re: WYVERN
Post by: b.lindsey on October 26, 2014, 03:36:48 PM
It'a a beauty Mike, and a fine runner too!!

Title: Re: WYVERN
Post by: Dave Otto on October 26, 2014, 04:05:13 PM
Nicely done Mike!

Congrats on a great looking and running engine.

Title: Re: WYVERN
Post by: MIKETANGO on October 26, 2014, 05:10:06 PM
Hi All, I am amazed at this reaction, I live in an area where I do not have direct contact with liken interests but have to to rely on people like yourselves which is a wonderful thing. Thank you.
          The Wyvern is running on Propane via regulator and demand valves, after a few tweaks and bit more running  will try switching to petrol however I am quite happy with Propane. It is built entirely to plan with the exception of having replaced the exhaust valve guide with a inlet valve guide,  3 piston rings and a longer Con-Rod bringing the Piston flush with top of the cylinder, just to get that illusive  magical 75 PSI? Being a purist and  authentically to the 19th century ect. Mine had to run on this funny looking carb. with its twin jets looking so unreal yet so 19th century, how do they run, Amazingly started quite easily on Propane once I had sorted out a few problems. I Have not yet attempted to start it with the starting handle, not that brave yet!
           I hope I have answered all the  questions, interests and for those not at the finishing line please keep trying and you will see the reward. the furthermore I have a web site if you wish to visit!

Title: Re: WYVERN
Post by: fumopuc on October 26, 2014, 05:33:23 PM
Hi Mike, congratulations for this runner. I have a lot of respect for these propane fueled engines.
Title: Re: WYVERN
Post by: Roger B on October 26, 2014, 06:45:45 PM
Congratulations on a great runner and an excellent video.  :praise2:  :praise2:

From the opening scene in the video I thought you were going to use the handle  ;) maybe next time?
Title: Re: WYVERN
Post by: Nemt on October 26, 2014, 08:16:17 PM
Hello Mike,

I like the Way your engine is running.
I build one myself from the scrapbox and some home made castings.
As much as I could according the drawings.
Mine has always run on propane and always runs very well sometimes for hours on shows.
I can can handstart it with a twist from my right hand.

It is allready some years ago I fineshed it, but it is still my favourite engine.


Title: Re: WYVERN
Post by: Tennessee Whiskey on October 26, 2014, 10:01:29 PM
Mike, wot they all said.  A very well mannered runner and the video made me want to take a good glass of wine to the garden and just listen to it run :praise2:

Title: Re: WYVERN
Post by: MIKETANGO on October 31, 2014, 04:19:02 PM
 Hi Everyone, I am truly amazed at the interest shown, Thank you. At the moment I running the Wyvern on the lathe (still a bit tight) about 8 hours so far. Sometime next week I hope I shall have it running under it's own steam (what a pun)
Title: Re: WYVERN
Post by: MIKETANGO on November 17, 2014, 01:06:20 PM
Hi Everyone, An Update to say Big Thank You to all and to say the  Wyvern is now running on Petrol or  Propane, the hot water in the tank makes good coffee. I believe we have a Total successful running Wyvern with that funny looking Carb.

Now to sort out my next project The Manx Norton Engine