Scale model Economy hit & miss engine builders wanted

[Charles 2010Participant @charles2010]

I wonder what the dimensions of the timbers are I guess about 38mm x 60mm

 

I like the cross members to give strength

 

Nice see such a fine picture too.

 

Regards Charles

Edited By Charles 2010 on 18/10/2010 20:44:42

[JasonBModerator @jasonb]

Much smaller than that, the model has 7″ flywheels and the timber is 20×26 finish size, for your slightly bigger engine something like 25×30 would look OK.

 

Have a look at some of the sites with photos of full size engines and base your design on that, wheeled trolly would look good The Florida Freewheelers photos here are a good place to start

 

Jason

[Charles 2010Participant @charles2010]

Thanks for the info Jason

 

I will look at various site and then decided but the 25×30 sound very good …

 

Regards Charles

[Anonymous]

I’m planning to mount my engine on a piece of jig plate, along with a separate fuel tank and ignition system. There should be room on the plate to mount something for the engine to drive, if I felt so inclined.

 

Regards,

 

Andrew

[Charles 2010Participant @charles2010]

Has anyone considered using a Helicoil in association with the spark plug to eliminate ware on the thread in the  Aluminium casting?

 

The idea was given to me by my car repair mechanic who thinks that a spark plug in aluminium is just asking for trouble …

 

http://www.helicoil.in/helicoil.htm

 

 

[Ian S CParticipant @iansc]

A bronze Helicoil would be best to aid heat conduction, perhaps not important in this case, but someone here in NZ put a stainless helicoil in thr engine of his ultralight aircraft, the spark plug over heated and the engine failed causing an emergency landing to be made writing off the aircraft. Ian S C

[Engine BuilderParticipant @enginebuilder]

Theading the cylinder directly for the spark plug is not a problem in our engines. No need to worry about it.

[Charles 2010Participant @charles2010]

Thanks for all the comments …  I will just thread direct …  the tap should arive early next week !!!!

[Charles 2010Participant @charles2010]

I decided that the safest way to hold the cylinder head for machining was to make up a suitable base to which the head could be bolted using the stud locations tapped M6.

 

This all works very well …  I have posted some photos  of the piece .

 

[Anonymous]

Hi Charles,

 

Thanks for posting the pictures. Looks like a nice solid arrangement.

 

Regards,

 

Andrew

[Charles 2010Participant @charles2010]

And I now realise that it will be used to machine out the valve seatings etc ..  They will be aligned in the 4 jaw chuck and all the finishing achieved for  each eg size and angle and 6mm ream.

 

At the moment I am waiting for tools to arrive so that  can continue …!

[John OlsenParticipant @johnolsen79199]

That is very practical…it would be an awkward piece to hold any other way.

 

regards

John

[Charles 2010Participant @charles2010]

Had I thought ahead more clearly such as I have done chatting away to a friend to night I would not have drilled the two valve guide hole from the top but marked them to be drilled from the inside.

 That would have relieved me of having to do very careful lining up to drill through correctly and I will not know that I have done so until I have the valves made and lapped in and proved concentricity.

 I have added to the photos my acetate drawings done on Autocad and printed out 1:1 that I used to pop mark the drilling positions – I used this as I could think of no other way of accurately drilling hole on a pitch circle with my limited engineering workshop..

[John OlsenParticipant @johnolsen79199]

I’ve used the printed template idea myself, in my experience it can give excellent results. Probably not as good as coordinate milling, the use of a rotary table, and so on, but as good as most work needs.

 

regards

John

[Charles 2010Participant @charles2010]

More photos have been posted …  The Cylinder head is nearly completed.

[Charles 2010Participant @charles2010]

Can anyone tell me the mass required to start compression the springs as it appears the the 1mm springs may be a bit heavy duty …  especially as the inlet valve relies on a vaccum in the cylinder to open ..

 

Any comments please ..

[JasonBModerator @jasonb]

Does sound a bit thick, the inlet one on my Zero-six are about 15thou and the Famous I’m doing at the moment calls for a 10thou spring. You really just need enough strength to overcome any friction and make sure the valve closes.

 

Jason

[Charles 2010Participant @charles2010]

I will use the springs that I have and if they prove to be to light then change them …

 

Thanks for you input …

 

I have put new photos in the album

 

Charles

[Charles 2010Participant @charles2010]

The governor ball have been attached to the wings. Photo in the album

[Charles 2010Participant @charles2010]

Can anyone explain how the Speed lever ( part 48) on the model Economy Engine works as I have yet to fathom it it including what parts connect together ..

 

Regards Charles

[Anonymous]

First, the speed lever. And as a rider, I’m typing this after a couple of pints of beer, so don’t blame me if it’s nonsense! I think the speed lever (48), the speed screw (51) and speed spring (52) form a spring loaded stop against which the striker arm (44) operates. The nearer to the cylinder head the speed lever is, the harder the striker arm has to push against the spring in order to hold the exhaust valve open. To generate the higher forces the governer has to run faster. Does that make sense?

 

Charles: Looking at your pictures, is your rocker arm an iron casting? Mine was a crappy light alloy casting that is too small to start with! I’m still deciding what to do about it.

 

Regards,

 

Andrew

[Charles 2010Participant @charles2010]

Hi Andrew

 

No the rocker arm was a crappy brass casting which in due course will be changed by the supplied who admitted was not up to their usual standard ..I am still waiting for the replacement..  So if yours came from the same place I would ask for a replacement  or consider making from solid as I did for the governor  and that was an interesting bt of turning and milling.

 

I am using the existing rocker1 to be able to “get on” with the build ..

 

I too have had an evening out so Ii will re-read your comments in the morning and try to sort out the parts drawings to try to get a picture in my mind ..

 

As always thanks for the comments.

 

Charles

Edited By Charles 2010 on 05/11/2010 23:24:35

[Charles 2010Participant @charles2010]

I am understanding the principle of the speed lever from your explanation but now I need to work out how the parts fit together. Maybe when I have made the part it will become much clearer …

 

More photos added to site .

[Charles 2010Participant @charles2010]

more photos added ..

 

All the keyways cut and the flywheels set in position.

 

The engine has reasonable compression but I am wondering if the inlet valve spring is still too strong.

 

May be the exhaust sprng is not strong enough. All will be found out when I try to run the engine.

 

I still have the timing and ignition side of things to sort out as well as oil cups etc etc etc … …  but hope to try to run it next Saturday 20 Nov for the first time.

 

 

Regards Charles

 

[ronnie barkerParticipant @ronniebarker18785]

charles

 

you are making a lovely job of this engine but please dont fall into the trap and set your engine up to run correctly.

 

ive seen so many nicely built engines dont run as they should ie hit and miss, even the engine on L A services stand fires everytime , ive said to them about it with no reply.

 

keep up the good work

 

jonathan

[Author]

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