Atkinson frustrations

[GordonL]

This post is to vent my frustration but if someone has some insight it is certainly welcome. I am building the Atkinson Differential engine from the Gingery plans and I am not having any luck in getting to run. Gingery said that he had to turn the engine over with an electric motor and a belt to the flywheel for up to 40 hours to seat the rings before it would start dependably. I have been doing that for quite a few hours (25-30) but I am not seeing any improvement. I am sure that the problem is compression but a solution escapes me. Due to the unique design you can only feel the compression on the last portion of the compression stroke because the spark plug hole is covered until the last part of the stroke. There seems to be good suction at the spark plug hole on what would be the exhaust stroke.

At this point it kind of fires about 1/3 of the time and even that is intermittent. If fires for a while and then quits firing until something like carburetor adjustment or cool off occurs. I have tried different spark timing and different carburetors and carburetor adjustments but nothing seems to change. I am using the S&S ignition and there seems to be a good spark.

At this point I am reluctant to remove the pistons/rings for inspection because if they are actually seating the rings are going to be in a different rotation when it is reassembled which I assume would at least partially disturb the seating in process.

There seems to be a surprising lack of information and build logs on an engine which has been built by quite a few others. There are quite a few Youtube videos. There are several errors or at lest omissions on the drawings but I have not seen any reference to this by any others. I have been over by engine and checked it to the drawings many times and as far as I can tell it is made correctly.

[Alyn Foundry]

Hi GordonL.

I'm unfamiliar with this particular IC engine but assume it has two opposing Pistons from your description?

You mention suction through the plug hole on the exhaust stroke I would have expected quite the opposite as you should be expelling the spent gases. Is it a case of " reverse rotation " ?

Is it possible to make a short, close up video of the engine being turned by hand, going through the motions? Pictures are worth many words.

Cheers Graham.

[GordonL]

You are correct that normally you would have pressure but when turning over by hand the one piston (left) remains stationary for part of the stroke while the opposing piston (right) is retracting, thereby creating suction. At the end of the stroke the exhaust valve is forced open to exhaust the gasses.

[Dave Otto]

My buddy Max has built many IC model engines and this is the only one that he ever had to motor to get running.
He is not a big forum or email fan, but if you would like chat with him I can give you his number.

http://www.modelenginemaker.com/index.php/topic,7583.0.html

Dave

[MikeK]

Gordon, did you get this to run?  I've been reading through the book lately, before attempting construction.  Did you notice that there are a few errors?

Mike

[GordonL]

Gordon, did you get this to run?  I've been reading through the book lately, before attempting construction.  Did you notice that there are a few errors?

Mike

I never did it to run consistently. It sits on the shelf mocking me.

[gipetto]

I think it's basically the same thing as the comer knocker engine, but gasoline and lower compression ratio. I think if i was going to build it i'd look for working dimensions there and scale it down.

[GordonL]

I think it's basically the same thing as the comer knocker engine, but gasoline and lower compression ratio. I think if i was going to build it i'd look for working dimensions there and scale it down.

Dave Perreault did sell plans and castings for a smaller version. I am not sure if he is still around.

<a href="https://www.youtube.com/watch?v=Y174HXyq1mg" target="_blank">http://www.youtube.com/watch?v=Y174HXyq1mg</a>

[MikeK]

Oh, that's the Differential engine.  I thought you built the Cycle engine.  I think both flywheels are too big for my 7x mini-lathe.

[Alyn Foundry]

I think it's basically the same thing as the comer knocker engine, but gasoline and lower compression ratio. I think if i was going to build it i'd look for working dimensions there and scale it down.

Sadly, nothing like the Commer TS 3 engine.

The TS 3 diesel engine is a basic ‘ blown ‘ two stroke. ( two piston, common bore  with 3 cylinders and 6 piston’s ) The pistons move at the same rate from opposite directions to make the combustion chamber central. Compression and ignition through the forward stroke, power and exhaust on the return stroke. One flywheel revolution.

   Graham

[gipetto]

Sadly, nothing like the Commer TS 3 engine.

The TS 3 diesel engine is a basic ‘ blown ‘ two stroke. ( two piston, common bore  with 3 cylinders and 6 piston’s ) The pistons move at the same rate from opposite directions to make the combustion chamber central. Compression and ignition through the forward stroke, power and exhaust on the return stroke. One flywheel revolution.

   Graham

could you configure a pair of atkinson differential engine as a boxer split single, think of it as bending each opposed piston cylinder in the middle by 180degrees. that should raise efficiency since there's not as many reciprocating linkages.