Polly Models AGE

[steamdaveParticipant @steamdave]

Has anyone made the Polly Models Atmosheric Gas Engine and got it to run successfully?

It looks an interesting little engine but I understand it can be a real challenge to get it to run because the original design from the 1900s on which it is based used coal gas as fuel.

Dave

The Emerald Isle

[steamdaveParticipant @steamdave]

Anyone made one?

[NJHParticipant @njh]

I don't know about that one Dave but I can't get a squeak out of my Scott Vacuum engine!

They assure me that it does wok so maybe I'm not persistant enough. The making was fun anyway.

Regards

Norman

[JasonBModerator @jasonb]

Norman have a look on Madmodder for John (Bogstandards) build of the Scott, he did several mods and it runs.

http://madmodder.net/index.php?topic=4219.0

 

Dave, can't help either.

J

Edited By JasonB on 03/04/2012 21:29:31

[steamdaveParticipant @steamdave]

Norman

I made the Scott a couple of years ago and it fired up first time, much to my surprise for a flame licker. One change I made is to ease the flame path into the cylinder by arranging the graphite valve block to drop down to close the port, rather than lifting to close, as shown on the drawings.

I am trying to strip it down at the moment because I used antifreeze as a coolant and everything not painted has corroded quite badly. (I kept it in its own wooden travelling box and that exacerbated the problem). I thought antifreeze was supposed to stop that sort of problem?

One mod I read about somewhere that I intend to try is to bevel the inside of the intake port. Don't know whether it will have any effect, positive or otherwise, but it's worth a try.

Dave

The Emerald Isle

[NJHParticipant @njh]

Hi Guys

Well that's encouraging! I have spoken to several folk about this engine and the reply has always been :- " I haven't heard of anyone getting one of those to run ."

I bought this a couple of years ago as a quick project to make on a recently aquired new lathe. Apart from the vast amount of cast iron swarf generated all over my machine I enjoyed the build and all fitted well and moved smoothly. Your experiences prompt me to dig it out and try again to breath some life into it! I too will rearrange the carbon block as you suggest. One question for now – how much tension do you have in the springs? I assume that the carbon block needs to be held firmly in place but excessive friction must be avoided.

Regards

Norman

Edited By NJH on 04/04/2012 08:36:38

[steamdaveParticipant @steamdave]

Norman

Minimum friction in all moving parts is essential to success. Spring tension needs to be the bare minimum to keep the block against the cylinder head. The springs are too stiff as supplied, but take care and don't stretch them too much. If that has happened, cut off a couple of turns and try again. Guess how I found out!

Dave

The Emerald Isle

[steamdaveParticipant @steamdave]

John

Hope you manage to get back to the Scott quite soon. I had a look at your work over on MM and was mightily impressed. Don't let it gather too much dust!

It is. or in my case now, was a very interesting runner. Mine looks very sad at the moment with all the corrosion on the bare parts.

Dave

The Emerald Isle

[Ian S CParticipant @iansc]

Theres a picture of a drawing from ME of a vacuum engine in my album, thats all I had to build a good working motor. The other year I built Jan Ridder's little motor, it still won't work, I think a rebuild might be the only answer.

On my working motor the valve is a strip of cast iron 3/8" wide X 1/16" thick lapped to the valve area on the cylinder head, no springs, it holds to the head by suction. Ian S C

[steamdaveParticipant @steamdave]

Here's a picture of the modified head. I took the opportunity to put the bevel on the inside of the port while the head was off for the engine overhaul.

Dave

The Emerald Isle

[NJHParticipant @njh]

John

Thanks for the video. That immediately shows a difference to mine – hopefully the reason yours runs and mine doesn't! Whilst the shape of the burner in your vid. is the same as mine your flame is blue whilst mine is yellow!! ( I had expected blue – as in bunsen burner ) I've rechecked my construction with the drawing and it seems OK – tube length, venturi in the correct position, holes in the right place. Any ideas where I might start looking please?

Norman

[JasonBModerator @jasonb]

Norman look at the link I posted earlier to Johns build he gives details of the burner which if I recall were not as pollys drawings.

J

[NJHParticipant @njh]

Hmmm

Yes thanks Jason

This is a comprehensive and interesting build diary – shame I didn't see it before I made my engine!

( Note to self – in future search web before starting!)

I will check my burner further but is seems pretty much like John's except that his has a No. 5 jet whilst mine is a No. 8. Would this make much difference do you know?

Regards

Norman

Edited By NJH on 05/04/2012 19:16:43

[NJHParticipant @njh]

Thanks John

I will order a No.5 jet next week.

I like your valve linkages. They are much nicer than mine which are just as the plans. If I can get the beastie to show signs of life I will remake them.

I should say that to get it running would be good. I explained to my young Grandson the principles of its operation so the ability to demonstrate that would save a bit of face! I guess if it comes to it, and I fail, I will show him your video – but I can just hear him say "But why doesn't yours work………!"

Norman

 

Edited By NJH on 06/04/2012 11:50:37

[NJHParticipant @njh]

Hi John

Well it looks more finished than mine does!

You are quite right about pinning the joints on the valve linkage. I have already done this on the actuating lever / shaft as I was finding it slipping. I guess I will do the others when (note not IF now thanks to your encouragement!) it is working.

I note the honing sequence on your thread. This was something new to me and I was a bit concerned about spraying oil all around the workshop. My solution was thus:-

It contained all the oil, allowed progress to be observed ,made it easy to keep the hone moving smoothly, squirt in oil as necessary and provided some nice peaches as a bonus! As I say I didn't know what to expect or how long it would take but was quite easy in the end.

Cheers

 

Norman

Edited By NJH on 06/04/2012 16:08:27

Edited By NJH on 06/04/2012 16:10:16

[NJHParticipant @njh]

Dave

I'm sorry – I seem to have hi-jacked your thread but it looks as if either nobody has made the Atmospheric Gas Engine – or maybe they are just too depressed to talk about it!

If you do give it a go I would be interested to follow your progress – it is a nice looking engine.

Regards

Norman

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