Tiny I.C. Engine

[gbritnell]

As I mentioned earlier the governor weights and arms were supplied by Gail. Thanks again!

 

[gbritnell]

Here is a better picture of the head and rocker arm assembly. Along with this picture are a couple more of the crankshaft and an overall shot with the other flywheel slid in place. Tomorrow I will start on the carb.
gbritnell

 

[Parksy]

These engines are just awesome. Do the big ends need some sort of oil cup for longevity or does a drop of oil suffice?

 

[10K Pete]

Brian, your 'variations' are very interesting. Would it be possible for you to
post a couple of pics showing the lockout arm and pivot better??

Thanks,
Pete

 

[gbritnell]

I have to take the flywheels off tomorrow to drill and tap them so I will take some pictures of each individual part.
Actually it's George not Brian.
gbritnell

 

[10K Pete]

I have to take the flywheels off tomorrow to drill and tap them so I will take some pictures of each individual part.
Actually it's George not Brian.
gbritnell

George, I'm sorry. I've read so many posts today......

Pete

 

[gbritnell]

Hi Pete,
Here's the closeups I promised.
They include the lockout lever, the governor weight and arm, the governor arm bracket and the spool.
gbritnell

 

[gbritnell]

I have all the pieces finished. Just waiting for some 1/16 dia. brass tubing for the fuel line. I finished the carb, muffler, Hall bracket and magnet disc.
I radiused all the corners on the base and fuel tank. I filed and sanded all the machine marks. Funny how you can't see machine marks until you take pictures.
I have no idea what weight spring will be needed for the governor weights but threw something on them to keep the mechanism for locking out.
When I made my first engine I deviated from the drawing and made my own spark plug. This one has an 8-36 thread. The insulator is Corian.
gbritnell

 

[GailInNM]

Looks great George.
Gail in NM

 

[10K Pete]

That's a real beauty, George! And thanks a lot for the detail pics, they help a lot.

I must build a Tiny. Soon!

Pete

 

[Parksy]

Just lovely. I'm curious about the single pushrod. I understand that the vacuum pulls the intake open and inhales its air and fuel, but is this setup to keep things simple? Why not intake and exhaust pushrods?

 

[gbritnell]

Hi Parksy,
I really can't answer your question. I have thought about it ever since I got interested in old engines, gas and steam. My best guess is that if two cams and pushrods were used and the governing mechanism was to still lock out the exhaust then the intake would be opening and closing and the piston would be blowing air back through it into the carb. In doing so the moving air would be taking fuel with it and spitting it out of the intake tract.
In this single actuator setup once the exhaust is open there is no vacuum so the intake never opens.
On these engines one has to remember that the carbs were very simple and did not have a variable throttle, until later, so they used the governor for basically speed and power control.
Actually quite ingenious when you look at the whole picture.
gbritnell

 

[steve-de24]

George, you have made a very nice version of the Tiny, I particularly like your hit-n-miss latch mechanism. I will be interested to hear how the lapped aluminium piston in a cast iron cylinder works out - I hope you don't run into any problems with different rates of thermal expansion. By the way are the flywheels the standard 1.75 inch diameter? They look to be a bit bigger but that could be me getting confused by the perspective of the pics.
Many thanks for taking the time to post the info and photos.
Regards,
Steve

 

[gbritnell]

Thanks Steve,
The flywheels are 1.75 diameter. I had the other engine sitting on the bench when I started this one and didn't realize that I had made the first ones 2.00 or a touch under starting with 2.00 stock. I'm not sure how this one will run with the somewhat smaller wheels but as soon as I get the fuel line I will try it out and see.
gbritnell

 

[GailInNM]

George,
For what it's worth, the flywheels on my hit and miss "Tiny"'s are 1.75 diameter by .468 thick brass with a 3/16 inch thick rim. The engines are governed at 3000 RPM and run about 6000 RPM with the governor disabled. In the hit or miss mode they hit about one in every 10 revolutions at idle. At idle I cannot tell the difference if I remove one flywheel. I run these engines at the high 3000 RPM as I use them to power gauge one locomotives.

With one flywheel removed, the only time I can tell the difference is when the engine is loaded I get a few more double hits to bring it back up to speed when both flywheels are installed. I think this is because of the increased inertia of the two flywheels. With either one or two flywheels installed about the lowest reliable governance speed is about 1600 RPM. This is with a 5 to 1 compression ratio.
Gail in NM

 

[gbritnell]

Thanks Gail,
That gives me an idea of what to shoot for.
gbritnell

 

[Parksy]

Hi Parksy,
I really can't answer your question. I have thought about it ever since I got interested in old engines, gas and steam. My best guess is that if two cams and pushrods were used and the governing mechanism was to still lock out the exhaust then the intake would be opening and closing and the piston would be blowing air back through it into the carb. In doing so the moving air would be taking fuel with it and spitting it out of the intake tract.
In this single actuator setup once the exhaust is open there is no vacuum so the intake never opens.
On these engines one has to remember that the carbs were very simple and did not have a variable throttle, until later, so they used the governor for basically speed and power control.
Actually quite ingenious when you look at the whole picture.
gbritnell

Thank you George. This makes sense. I will use this style for my next project.

Cheers!

 

[gbritnell]

Gentlemen,
The Tiny air cooled engine lives! The only problem I had was I first tried running it on straight gas and it stuck the piston a couple of times. The piston was lapped to the cylinder so it probably only had a couple of tenths clearance. I then mixed up some synthetic 2 cycle oil in about a 40:1 ratio and it solved the problem.
I can run the complete tank of fuel through it with no overheating and no sticking.
https://youtu.be/mbiM_qRLj8M

 

[kuhncw]

Nicely done, George. The engine sounds good and it is certainly a busy little guy.

Chuck

 

[steve-de24]

Congratulations George on a nice running engine. Can I ask about the crankshaft ball bearings. Are they retained only by the pressure from the bearing caps or is there some other way to stop them moving along the crankshaft that I cannot make out from your photos?
Regards, Steve