Opposed 4 cylinder 4 stroke

[geoff_h]

Hello, this is my first posts to the forum but I have been reading, admiring and learing by reading here sense Ive started machining.

This is my 2nd IC build. 400 hours work over the last 7 months and about 400 parts finally came to life and I got it running reliable yesterday.

It currently runs on glow fuel but I would like to eventually convert it to gas and fit a CDI ignition.

I dont have any build pics, just pics of the parts as they where completed.

The engine is a 120cc 4 cylinder 4 stroke. The plans are from Germany. I did a fare amount of modifying and redesigning the parts. More to experiment then to fix problems. Also to convert all the metric dimensions to imperial as thats the only tooling I have.

Here is where I found the plans. They have many aero motors and that is my real passion.
http://www.cad-jung-shop.de/epages/62479729.sf/en_GB/?ObjectPath=/Shops/62479729/Categories/Bauplane

[ame]http://www.youtube.com/watch?v=IKeifHljhjg[/ame]

2nd test run 600 rpm idle 5200 rpm at 3/4 throttle.

[ame]http://www.youtube.com/watch?v=-sv1kC3jiUs[/ame]


The pistons and rods are 2024, intake and exhaust is 304, cast iron cylinder sleeves, valves are 416 and bronze on the valve cages and bushings.

The exhaust tubes where filled with lead bent using a custom made bender then the lead was melted out.

I made a custom valve seat cutter that I learned about from this forum and it worked perfect, only a light lapping was needed.

The valve springs are wound on the lathe using a technique I found online. They are then stress relived in a toaster oven. They where easy to make but tricky to make all the same.

The rods have needle bearings in the big end and bronze bushings in the other.

The roller rocker arms are 6061 with hardened W1 rollers and roller shafts.

 

[lazylathe]

Looks great so far!

Judging by my poor eye you have a CNC machine at your disposal??
All the parts look great!

How about an intro post in the Introductions section?
Tell us a bit about you and what you do!

Andrew

 

[geoff_h]

The head gaskets are turned from .005 copper shim stock in aluminium jigs the other gaskets from .020 copper.

The rings are cast iron and made using a technique from SIC where they are turned to size then heated on a mandrel to hold the new shape.

The fuel splitter is brass and silver solidered

The brass intake and exaust couplers are free to turn on the 304 tubing and have brass flanges silver soldered in place to hold them into the ports. This allows them to be set to any position then the coupler is tightened to hold them in place.

 

[geoff_h]

Looks great so far!

Judging by my poor eye you have a CNC machine at your disposal??
All the parts look great!

Thank you.

Everything was made manualy on a 13x40 Import lathe and 9x46 Wells Index mill.

 

[cfellows]

That's a great looking engine. Runs very nice. I especially like how low it idles.

Do you have any pictures of the crankshaft? I'd be interested in seeing how you hold it together.

Chuck

 

[geoff_h]

This was the first crank built to the original drawings. Its turned from 1144 and the rod journals are hardened shaft. There is a splined connection to allow for 2 bearings in the middle of the crank. Everything is held together with machine screws.

The crank proved to be weak and in the first runs the front crank sheared at the bolt that pinches the rod shaft.

 

[geoff_h]

Here is the 2nd version of the crank and rods. Crank is again 1144 and the rods are 2024 with bronze bushings in the small end. the big end is reamed and held together with 2x 2x56 screws. The crank is made in 2 parts and turned between centers. Not shown is the coupler that holds the center joint. Its just a tube with the id the same as the bearings to be a firm slide fit onto the crank halfs and holds them together as 1 removing any side play from the bearings.

The 2nd set of pics show how the crank is supported in the case. 2 bearings in the nose, 2 in the middle and 1 in the back.

The holes in the bottom of the case allow oil into the cam housing and are countersunk for o-rings to seal them.

The drive key is custom made.

 

[geoff_h]

The carbs are standard RC carbs with new throttle arms made.

The first cam was made of W1 but when hardened twisted and was not usable. All part of the materials learning curve I guess. The 2nd cam was redesinged and made of O1 and was thicker diameter between the lobes to try and allow it to be more stable when hardened. It is 270 intake 270 exhaust and 110 degrees between the lobes

 

[geoff_h]

Everything put together and ready to run. Now the real fun starts, to try and refine it.

 

[mu38&Bg#]

Beautiful. I'm going to guess, die maker?

 

[geoff_h]

Beautiful. I'm going to guess, die maker?

Thank you.
Im not a profesional machinist. Just like to tinker and make things.

Geoff

 

[lazylathe]

Awesome work!!!
You have a lot of talent!!

There are a few of us from the Southern Ontario on the board.
I am in Woodstock.

Love the video!!
Are you going to put it in a plane and fly it??
That would be the ultimate scratch build!!!

Andrew

 

[geoff_h]

Awesome work!!!
You have a lot of talent!!

There are a few of us from the Southern Ontario on the board.
I am in Woodstock.

Love the video!!
Are you going to put it in a plane and fly it??
That would be the ultimate scratch build!!!

Andrew

Thanks to everyone for the kind words.

I live south of Woodstock in Port Rowan. Not sure if I am going to fly it. I have never had a plane bigger then 28% and this would need 35% or bigger, a big investment in money. Also it goes through alot of glow fuel. On gas it would be much cheaper to fly.

Thanks
Geoff

 

[Lakc]

Not sure if I am going to fly it. I have never had a plane bigger then 28% and this would need 35% or bigger, a big investment in money.

You can always add lead to the tail.

Nice job!

 

[geoff_h]

Had another good test run today after some intake tweaks. 600 rpm idle 5200 at 3/4 throttle.

It hits the wall at 5100-5200rpm with throttle remaining. I think the valves are starting to float. Next step will be to make a stiffer set of valve springs and a stronger set of pushrods.

[ame]http://www.youtube.com/watch?v=-sv1kC3jiUs[/ame]

 

[metalmad]

Nice Job Mate
that thing has a bigger prop then my lawn mower has blades, I love it !! :bow:
I want one :big:
great job
Pete

 

[Hinckley_Bill]

My Dad was a 30+ year Tool and Die Maker from "the old school".....if he had lived long enough to enjoy himself he would have marveled at the work you have done on a home setup.

Thanks for inspiring us.

Bill

 

[MuellerNick]

Hi Geoff!

A really nice and clean looking engine. Great work!
Sad, that you had to give up on the Hirth-coupling of the crankshaft.

Only thing I have to criticize is the intake manyfold. It is not to your standard. But you intended to replace it later anyhow, right?

Great work!
Nick

 

[JaamieG]

Very neat crankcase design.
Excellent work.
Cheers,
Giacomo

 

[agmachado]

Hi Geoff,

Very nice job... and thank you for share with us... including the germany web site with others engine plans!

Cheers,

Alexandre