Opposed Twin I.C.

[canadianhorsepower]

Hi Brian

My suggestion is to cut your hole on a rotary table
incline to the degree you want your fins to be

my 3 cents :fan:

good luck

 

[Brian Rupnow]

You mention using dowels for the crankcase halves. The halves will have to be brought together in the direction of the crankshaft axis, but your joint lines are in the wrong orientation for this: the dowels would have to be removed to get the thing apart. By having the joints at right-angles to where you have them, the dowel axis can be in the direction of assembly. You would also need to move the joints to the opposite corners so the cylinder flange does not lie over the joint.

Charles--you are absolutely right. I will look at making that change tomorrow.---Brian ----Swifty---Great minds think alike (Or is it "fools never differ")--That is exactly what I'm thinking of doing. My bandsaw is a converted wood bandsaw and has no feed mechanism. My big old power hacksaw will possibly do the job If it has enough stroke.

 

[Brian Rupnow]

Hi Brian

My suggestion is to cut your hole on a rotary table
incline to the degree you want your fins to be

my 3 cents :fan:

good luck

I thought of that Luc, but I'm not sure I will live long enough to hog out all the material between the fins. It would be a great CNC job though, to just program, set it up, and let it run all night.

 

[Brian Rupnow]

I've spent the best part of this morning tweaking the model. I had the overlap in the main frame going the wrong direction, so I changed that so the bolts. dowel pins, and crank and camshafts were all in the same plane. I went to a centrally mounted single camshaft, which does indeed simplify things.

 

[Charles Lamont]

I still think the crankcase joints would be better on the opposite corners which would seem to have less going on.

You might get some ideas from the Mastif flat-4 design by LC Mason:
http://modelenginenews.org/gp/mastif.jpg

 

[Brian Rupnow]

I already have an "ignition box" containing a standard 12 volt automobile coil, which is wired appropriately with two leads and a high tension wire. It runs in conjunction with an extra 12 volt battery that I have had for years. Since I have 8 or 10 different engines, all single cylinder, with their own points and condensers, I can "plug and play" whatever engine I want into the "ignition box". I did this because coils are expensive at about $50 each. i don't want to buy an electronic ignition nor a special coil. I think I can probably make a "splitter box" out of non conductive material which has the coil wire connected to one port, with two separate ignition leads coming out of it, one going to each sparkplug. I see no reason that wouldn't work. Has anybody done that?

 

[Brian Rupnow]

Okay---now we're at the "what if" stage.--I'm not likely to do this, but IF I decided not to run the engine with an open crankcase, it would be simple to add a couple of gaskets and a top cover. If I ran a cover, then I would need to run some oil in the base for splash lubrication.--As Jason pointed out, this would lead to other issues, with the clockwise rotation flinging oil into the "down-wind" cylinder and loading it up with oil. Really, at this point I'm just "imagineering".

 

[gus]

I can hear it running from faraway Singapore!!!!

 

[Brian Rupnow]

I can hear it running from faraway Singapore!!!!

Gus--It certainly makes an interesting model. Nothing really extraordinary there either, because I've built most of the tricky parts before on the Canadian Cub. I think I'm going to buy a new lathe this coming week. It has a 3 year guarantee, but if you read the fine print, the 'labour' part of the guarantee is only good for 90 days. I'm not even going to move the lathe into my machine shop. I will set it up in my main garage and run the crap out of it making all the round parts for this engine. If it doesn't blow up in the first 90 days, then it will probably last forever.---Brian.

 

[vascon2196]

Wow...is this engine modeled after an old Maytag? Why have I not seen this yet...looks very, very, very cool.

 

[Longboy]

Okay---now we're at the "what if" stage...... If I ran a cover, then I would need to run some oil in the base for splash lubrication.--As Jason pointed out, this would lead to other issues, with the clockwise rotation flinging oil into the "down-wind" cylinder and loading it up with oil. Really, at this point I'm just "imagineering".

You (may) not need a splash here, not even for a horizontal cylinder. The WD40 blow by down the cylinders will fling off the crank webs and onto the camshaft. Also a gravity lube reservoir over the cylinders like you see on hit & miss engines looks fanciful. --- Dave.

 

[Brian Rupnow]

Wow...is this engine modeled after an old Maytag? Why have I not seen this yet...looks very, very, very cool.

Chris--you haven;t seen it before because I only started it on Wednesday. It is not a model of a Maytag, Maytags were 2 cycle. However, if you look at post #5, the Maytag layout is my inspiration.---Brian

 

[vascon2196]

Ahhhh...well I'm glad I stumbled on this. I own 2 Maytag engines and am hooked. I like the look of this engine...your design process is spot on too. I'll be watching until the end.

 

[Brian Rupnow]

I don't really care for the look of that tall base. Of course, it has to be that tall to accommodate a 6" o.d. flywheel. Really, the working part of the flywheel is only 4 1/4" diameter.

 

[Jasonb]

Brian, can't you just mount the engine on a wooden display stand and let the flywheel hang down the side?

 

[Brian Rupnow]

Brian, can't you just mount the engine on a wooden display stand and let the flywheel hang down the side?

Jason--I am considering that.

 

[Brian Rupnow]

I shortened that base up as much as I could, and I flipped the toes of the angle frame to get my cylinder bases all on one surface. I like the proportions much better this way, although it will have to set up on a wooden base to get flywheel clearance. Dang, I like that flywheel!!!

 

[Brian Rupnow]

My plan is to have the two cylinders running on opposite cycles. When one piston is coming up to top dead center under compression stroke, the other is coming up to top dead center on exhaust stroke. That way I get a power pulse every 360 degrees of rotation.-----Brian

 

[barnesrickw]

Brian, you mentioned some "voodoo" when talking about the timing on the two cycle Maytags. I remember when researching Saab 2 cycle, three cylinders, there was some voodoo involved there. I would like to figure that out someday.

 

[Brian Rupnow]

Brian, you mentioned some "voodoo" when talking about the timing on the two cycle Maytags. I remember when researching Saab 2 cycle, three cylinders, there was some voodoo involved there. I would like to figure that out someday.

Jan Ridders seems to have success with the two stroke engines he builds and runs. Everybody else I have ever heard from who built his engines to spec had a horrible time getting them to run. Many, perhaps most of them ended up holding down shelves as nicely executed ornaments.