tiny four cycle

[putputman]

So another part to the scrap bin.

With the size engine you are building your scrap bin can be the size of a match box.

Been following your post closely as I am in the process of building an engine with 3/8" dia. piston and 1/2" stroke. Been wondering how I am going to get 2 valves & a spark plug in that small area. Your post has given me a lot of hope now.

You mentioned using a 8-32 cap screw for the spark plug but later said it was made from alum body, teflon insulator, & drill blank electrode. Did I miss something there? Have you tested the plug? Looks like you are going with a surface gap. Sure would like more details on how you made it. It is considerably smaller than Geo Britnell's plug.

 

[Krown Kustoms]

Sorry about the plug, I forgot that I left that as a dead end.
I was going to use a stainless cap head screw.
After looking at it it just looked cheap, so I started on one out of Al hex, and accidentally drilled all the way through for the electrode.
So I decided to make it a surface gap plug. I dont think it will be hot enough but I havent tested it yet.
I made a coil but it dosent have enough kick, I found a small transformer that I think will work.

I havent drilled the ports in the head for the carb and exhaust but they are going to be at 90's from the spark plug end of the head.
-B-

by the way, dont laugh at my pic (well not hard) I dont have any drawings of it on computer yet.

 

[Krown Kustoms]

I got the crankshaft done, but I cant find my camera.
I need to start keeping it in the small parts can, so I know where it is.
I will post some pics when I find it.
It shouldnt be hard to find, it is only the color of all of the swarf piles I have accumulated
-B-

 

[Krown Kustoms]

Hey look I found my camera, it was in my bedroom.
I dont remember puting it there.

Here are some pics of the crank shaft.
The threads were a P I T A to cut, I guess I hardened it when turning down the shaft.

I am working on the rod and piston now.
I will take progress pics unlike the cs.
-B-

 

[Krown Kustoms]

Back again, I cant leave this thing alone.
I had to modify the crank case to accept the rod, I made a temporary rod out of brass to check for this very problem.
After a quick fix Im back on track.
I not sure what I am going to make the rod out of, probably stainless.

here are a few more pics.
-B-

 

[cobra428]

Nice, -B- your coming along nicely
Tony

 

[Krown Kustoms]

I havent had much garage time, but I have been playing with Alibre.
I will eventually have a cad drawing of the engine that may never run.
-B-