Economy Hit & Miss Engine Build.

[Nick_GParticipant @nick_g]

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For work on the cylinder head I made a jig to the style suggested by Jason.

Added some PCD holes to both the jig and the head casting.

The valve holes were dialed in while the jig assembly was mounted in the four jaw chuck.

TBH I forgot to photograph most of the stages of the head machining.

I will leave the lathe topslide angle setting untouched until I have machined the valves. (also suggested by Jason) so that the angle of the valves and the seats match as closely as possible for final lapping.

Bit more painting in primer of paint and rub down several times.

Added the oilers to the bearing caps.

Then some coats of final colour.

When dry I masked off with tape for the pin striping.

Over to the cylinder / hopper to drill and tap the hole for the spark plug. – For some reason I found this step quite nerve wracking.??

Then more priming, rubbing down and priming.

Nick 

 

Edited By Nick_G on 14/04/2017 11:13:18

[Neil WyattModerator @neilwyatt]

Neat

[JasonBModerator @jasonb]

Posted by Nick_G on 14/04/2017 11:11:20:

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I will leave the lathe topslide angle setting untouched until I have machined the valves. (also suggested by Jason) so that the angle of the valves and the seats match as closely as possible for final lapping.

Oh no I didn't!

Though it won't do any harm, the main thing is to drill and ream the valve giude, open up the cavity behind the valve head and cut the valve seat all at one setting which gives the best chance of things being concentric.

Just a note for next time, I prefer to put the inlet and outlet passages in after tdoing the above that way the drill is always cutting into solid metal so less risk of it wandering as it hits the cross hole.

Now hurry up and get those red pinstripes done so we can see how blingy it looks

[Nick_GParticipant @nick_g]

Posted by JasonB on 14/04/2017 13:28:09:

Now hurry up and get those red pinstripes done so we can see how blingy it looks

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I am ahead of you.

Nick

[Nick_GParticipant @nick_g]

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Valves.

Asked a mate of mine to drop off a bit of 16mm stainless steel. He came with about a meter of what is known as 431S29 stainless and exchanged it for a brew and some biscuits.

I know nothing about this material other than it was really nice to machine and that he told me it's one of the magnetic stainless steels.

I remembered to leave a bit of a stub on this time to make the lapping process a bit simpler.

The above is the inlet valve which is an atmospheric one. I have read that the supplied spring is a little strong for the job so have made the stem little longer so I can place the retainer higher so that there is not as much pressure on the inlet spring. If it proves to be not strong enough I can put the retainer further down the stem with ease and not have to make a whole new valve from scratch. ………… Or get a weaker spring.!

Nick

Edit :- Just found a data sheet for it if anyone is interested. http://www.atlassteels.com.au/documents/Atlas431.pdf

Edited By Nick_G on 16/04/2017 11:04:50

[Nick_GParticipant @nick_g]

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Started to tidy the exhaust rocker valve and made a bush for it out of PB.

With me starting to put the basic engine together as I have painted quite a few of the main castings I am aware of the increase in weight. As this is the all cast iron version and not the aluminium one the weight is considerable for a model (about 90 – 100 lbs assembled) Not wishing to tip all that upside down and ruin the paint I decided it best to make and install the fuel tank as this is located on the inside of the base casting.

I made this out of double sided copper clad fiberglass board that is normally intended to making into printed circuit boards. – I got this idea from my ham radio construction days when such boxes were often made to go inside equipment and provide an RF shield.

I used a 150w soldering iron that had more than enough whack in it to run the joints. The photos should be self explanitory how I did it.

Tacked the boards.

Ran the solder joints.

Filler flange.

Getting there and running the joints on the other side.

Finito'

Fixing is via silicone.

Nick

[Benny AvelinParticipant @bennyavelin86238]

It's looking great! I wish I had you painting skills/patience.

[Nick_GParticipant @nick_g]

Posted by Benny Avelin on 27/04/2017 20:59:06:

It's looking great! I wish I had you painting skills/patience.

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Hi Benny and thanks for the kind remarks.

Truth is though I do not really have any painting skills.! It's the result of nothing more than 'rattle cans' and masking tape for the pin stripes. Get close and it is a bit 'orange peely' on the finish. I probably would have got a better finish if I had got the air brush out.

I did however spend considerable time in the prep stages, but that is no secret be one painting a house, a car or a model etc.

I know nothing I ever make will ever win any competitions but I have in my limited time in the ME world seen lots of beautifully crafted and engineered items that have the visual edge taken off them by a whack it on paint job.

As I said it's all in the prep. – A Dremel, JB weld, Milliput, car body filler, primer and wet & dry are my new best friends.

Nick

Edited By Nick_G on 28/04/2017 12:31:35

[geoff walker 1Participant @geoffwalker1]

Having seen this project first hand I can certainly vouch for the excellent finish and overall build quality.

I would expect nothing less from a fellow Warringtonian

…..and it had pride of place on the dining room table!!!

geoff

[Nick_GParticipant @nick_g]

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Some self explanatory progress photos.

Have a good weekend folks.

Nick

[Benny AvelinParticipant @bennyavelin86238]

With a fear of sounding repetitive, it looks amazing! You can certainly be proud of this, no need to be so humble.

[Neil WyattModerator @neilwyatt]

I'm sure that would be in with a good chance of an award finished to that standard!

Neil

[Nick_GParticipant @nick_g]

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Did some work on the timing plate and made the push rod and contact block etc. Still need to remove tool marks and the end of the push rod where it meets the rocker is not final.

And a little video overview.

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Nick

[Nick_GParticipant @nick_g]

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Been a while since last post as I have been making the fiddly bits to get the engine running.

Finally got it far enough that I could try a test fun as I wanted to know the basic engine was sound. I had managed to get a 2nd hand .60 sized R/C carb off ebay to use as a temp one for testing.

Few issues. Firstly was the compression. When I fitted the cylinder head I realised there was not a whole lot of compression. I really should have addressed that issue then before I went any further. So I had to take the head off and re-lap the valves. …….. I then had loads of 'ploppy-floppy' compression.

Next I could not get the buzz coil working properly to give a strong and reliable spark. Being the impatient sort I dumped that and hogged a temp normal ignition circuit up. (I will address the buzz coil later)

The carb I have is a bit large and once I started to get the thing kicking back at me from hand spinning the flywheels I had a fair idea that it was just a matter of the carb and ignition timing settings to hopefully get the basic engine tested.

As yet I don't have the hit and miss governor fitted as that is one more thing to have an issue with for testing. I again will sort that out later. But for now it's running as a 'normal' !!!! 4 stoke.

Anyways, please forgive the shakey video as I just grabbed the camera and TBH was half expecting to have to stop it jumping off the bench.

Nick

[JasonBModerator @jasonb]

Sweeeet, ain't much wrong with that. As you say now that you know it is a runner you can add on the other bits a piece at a time without the problem of 99 possible combinations of what may be stopping it from running.

J

PS You need to find a decent electrician to sort out your buzz box

[Neil WyattModerator @neilwyatt]

Triple congratulations:

1. A nice job.
2. Getting it to run sweetly.
3. Keeping your vid to a sensible length!

Neil

[Martin CottrellParticipant @martincottrell21329]

Superb Nick! Sounds and looks fabulous, just needs a nice trolley to sit it on!

Martin.

[Nick_GParticipant @nick_g]

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Thanks for the remarks guy's

I now know I have a working foundation to build on and adjust.

Nick

[Benny AvelinParticipant @bennyavelin86238]

Sweet indeed! Lovely sound on that engine.

[Colin HeseltineParticipant @colinheseltine48622]

Nick,

Very nice job on this model engine. I have just bough the castings from Engineers Emporium and the small parts kit. I note that the cam is just the 6 mm thick and does not have the extra 6 mm to turn down to press into the bore of the gear. How did you do this as its was not entirely clear(to me) by looking at the photographs.

Thanks,

Colin

[JasonBModerator @jasonb]

Nick won't be able to answer.

[Colin HeseltineParticipant @colinheseltine48622]

Thanks, Jason

[JasonBModerator @jasonb]

Colin, it looks like Nick may have bored the cam out to 20mm and then pressed that and the gear onto a 20mm steel bush and then pressed in the bronze one, you could probably do the same or press them both onto a 20mm OD x 10mm ID bronze bush. The cam is not heavily loaded so Loctite would also work in place of or in addition to a press fit.

[Colin HeseltineParticipant @colinheseltine48622]

Jason,

Thanks for that. I had a feeling that was what he had done but wanted to confirm.

At present I am reading through the plans book deciding where to start. I need to finish the Excel die filer arms I have just had cast first.

Colin

[Anonymous]

I made my cam from a solid piece of gauge plate. But I bought my Economy kit many years ago and didn't get much in the way of materials other than the castings. I did get a flame cut conrod (eventually) but binned it as it was too thin. I also binned a number of the castings, especially the smaller light alloy ones.

There are, or where, a number of errors in the drawings. One blooper is the requirement for 1/2" BSP threads for the exhaust and carb fittings. The designer obviously assumed that 1/2" BSP was 1/2" OD. I used M12 instead.

Andrew

[Author]

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