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Building a Flat Twin

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teeleevs

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Looking good, here are some shots from my day yesterday, photos 1 and 2 burying the patterns 3 get the furnace going, 4 open the Christmas parcel 5 ready for the shaper, have video of shaper trueing up the crankcase half an hour after pouring metal.
Thanks for watching
Ted
 

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Rdean33422

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I disassembled the engine yesterday and made the top and bottom plates. The top has a cutout inside for the cam gear. I also painted the plates last night but since it has been a little cooler here I didn't expect the paint to be cured. I have a toaster oven in the shop I use for different things but never tried to cure paint in it. I set the oven to 200 degrees for 35 minutes and laid the plates in on the rack. When the oven shut off I just opened the door and let the plates cool by them selves. This is a process I will be using in the future as the paint is rock hard with a very nice finish. I would not try this with freshly painted parts only ones left overnight as who knows what might happen.
I cut the crankshaft end to length, shortened the cam shaft, and drilled holes for the valve lifter bushings.
I left the rear end of the cam shaft long as I haven't decided if I will make a distributor or not.

Front view
GEDC4786s.jpg

Rear view
GEDC4790s.jpg

I also roughed out the 4 cam lobes.
GEDC4791s.jpg


Thanks for looking
Ray
 

teeleevs

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That's a good start when everything moves as it should, with a flat twin both pistons reach top (full compression in one and exhaust in the other ) so ignition only needs a twin lead coil fireing every time around with only one magnet or cam on the crankshaft, some COP Car coils run 2 plugs and will run on 4 volt can't say which but early Mazda or Ford badged Mazda models is a good try.
Ted
 

Brian Rupnow

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On the twin that I built, I ran a pair of automotive points off the crankshaft. That gave me a spark on each crankshaft rotation. I used a coil from a two cylinder snowmobile. The coil had two sparkplug wires. It fired both sparkplugs on every rotation. The cylinder under compression would fire, the other cylinder would be up on exhaust, so even though that plug fired, there was nothing in the cylinder to burn. The path that the electricity followed was crazy--It came out one wire, fired the plug, ran thru the block to the other plug and fired it, then ran back thru to the coil on the other plug wire. It worked great, but if you pulled either sparkplug lead, the engine would quit because you had totally broken the circuit. No distributor was required.---Brian
 

Rdean33422

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That's interesting Brian I had never heard of that configuration.
I am contemplating several different scenarios for this build.
One is to use a distributor with one ignition module and one hall sensor. I kind of like the idea of designing and making a distributor and it is a long time proven design with many millions of examples.
I could use two ignition modules each with it's own hall sensor firing just one plug each.
I could use an ignition module that is designed to fire two plugs which are 180 degrees apart.

I just haven't decided on any one type yet.

Ray
 

teeleevs

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Hi Ray, the ignition system Brian wrote about above is used in most v6 & some 4s car engines today. But going back into the 1970s Honda motorbikes used the system. Henry Ford had 4 Trembler (Buz) coils on the T Model and never realised he only needed 2, one of his greatest problems was to have his suppliers deliver him 4 Buz coils every 3 minutes. A few days ago I Posted pictures of a model Railway trolley I built, so here is the full sized one. Picture 1 & 2 a closeup of one side of the engine, it is 2 cylinder, it had a similar system to energise the 2 Buz coils as Fords T Model but Buz coils were invented for the overland telegraph system about 50 years before Fords first car. I used a set of points on the camshaft with 2 flats on the cam inside the round box, running a Honda twin lead coil.
 

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teeleevs

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Todays work on the Onan opposed twin, the fan, made entirely from polystyrene, picture 1, burying it in the clay, 2 turn the box over, 3 ready to pour metal, 4 just enough metal in the pot, 5 open the Christmas box, 6 looks like I might have gotten away with it. It run true in the lathe, a few imperfections but hey, what is paint made for? Would have been very difficult to do this with a wooden pattern.
Ted from down under
 

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MRA

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That's really neat! Did you carve those blades freehand? Lost polystyrene is one of the things I have not tried yet in my home casting adventures. The museum where I volunteer needs a thermostat body for an old Gardner diesel engine - it's a very odd shape and I can't work out how to do it with a conventional pattern. That might be an interesting way forward.
 

Richard Hed

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That's really neat! Did you carve those blades freehand? Lost polystyrene is one of the things I have not tried yet in my home casting adventures. The museum where I volunteer needs a thermostat body for an old Gardner diesel engine - it's a very odd shape and I can't work out how to do it with a conventional pattern. That might be an interesting way forward.
I did that in college class. The one warning I have is if there is a flaw, even a tiny one, it will show up exactly as y9ou see it on the polystyrene. Also, apparently, there are two types: one very poisonous which will melt or disolve with a bit of gasoline poured on it, so easy to detect. and the other which is far less poisonous. Other than these probs, the stuff is EASY to work with, I mean, the stuff can come out to 5-10 thou if you are careful. When I get around to foundry work, this technique will be a number one for me to use.
 

teeleevs

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I turned the main circles in the lathe then setup a Dremel machine on the Mill and marked out the blades on the rotary table from there on I used various sharp blades by hand. I often glue pieces together with Aquadhere but the resulting ash can affect the finish as noted by Brian above, so the less gluing the better. It can be cut with a sharp knife, hot wire, or bandsaw, doesn't cost much if lucky enough to pick up a chunk on the side of the road. Casting comes out a bit rough, takes a little more finishing. Give it a try.
Ted from down under
 

teeleevs

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More pictures of progress on my Onan opposed twin, the timing cover is a bit rough but there is a lot more to machine on it, a friend gave me a Lifan Chinese magnito so need to fit that, it is almost exactly the same as the original Onan one only much smaller, should work fine, it fits inside the fan come flywheel. Last picture the Onan original.
 

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davidyat

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Brian, I had a Honda 160 motorcycle, 4 stroke, that fired on every stroke like that. When I was racing motorcycles in the Mojave desert, my bike had 2 spark plug holes in the head, one being plugged. It was a 2 stroke Yamaha. I mounted the coil on the bike, stuck 2 plugs in the head and found out 2 plugs firing greatly increased the power.
Grasshopper
 

ddmckee54

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Teeleevs:

It looks like you're doing lost foam casting in greensand, is that correct? If you haven't been there yet, you might want to check out thehomefoundry.org. They've got a forum devoted to lost foam casting. It might make things a little easier for you. I'm amazed at some of the stuff that Kelly has cast with lost foam on that forum, his username is Al203. There are many tricks that you can use to get some outstanding surface quality.

Don
 

Richard Hed

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Teeleevs:

It looks like you're doing lost foam casting in greensand, is that correct? If you haven't been there yet, you might want to check out thehomefoundry.org. They've got a forum devoted to lost foam casting. It might make things a little easier for you. I'm amazed at some of the stuff that Kelly has cast with lost foam on that forum, his username is Al203. There are many tricks that you can use to get some outstanding surface quality.

Don
Don,
Is there another url? That one doesn't work for me. I'll search for it. Thanx

Whoa--the foundry is everything from weddings to church stuff. The nearest thing I found to this is The Foundry: NEK Vermont MakerSpace | The Foundry

OK, I found it but my ip address has been banned!?
 
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ddmckee54

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Try contacting an administrator there and explain what's going on. Otherwise PM me and I'll contact an administrator there and tell them about your problem.

Don
 

teeleevs

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Try contacting an administrator there and explain what's going on. Otherwise PM me and I'll contact an administrator there and tell them about your problem.

Don
Teeleevs:

It looks like you're doing lost foam casting in greensand, is that correct? If you haven't been there yet, you might want to check out thehomefoundry.org. They've got a forum devoted to lost foam casting. It might make things a little easier for you. I'm amazed at some of the stuff that Kelly has cast with lost foam on that forum, his username is Al203. There are many tricks that you can use to get some outstanding surface quality.

Don
Thanks Don, I tried a couple of different ways but thehomefoundry.org gave me a message that it was a dangerous site? Couldn't think that was right.
Ted from down under
 

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