Atkinson Differential

[GordonL]

Has anyone here built an Atkinson Differential using the design by Brooks Pendergrast? I built one using the Gingery plans a few years ago and was never able to get it to run so I decided to try the Pendergrast design. So far it I am having better luck on this design but I am having a problem with the engine running for about thirty seconds and flooding out. I can blow out the cylinder and clean the spark plug and it will run again for about 30 seconds. I am wondering about the intake port into the cylinder. Pendergrast says that a spacer is required on the valve so that it does not get sucked into the cylinder but the drawing shows a .250 hole through to the cylinder and a .375 dia. valve is not going to be sucked into the cylinder through that hole. I am wondering if that hole should be larger. The carburetor adjustment is extremely sensitive and the mixture is apparently not the best.

[propforward]

Hi Gordon, I don’t have any input, but I’ve pointed someone who knows Brooks to this thread, so Brooks himself may be able to help you out.

[55fairlane]

Hey Gordon,  Brooks is a dear friend of mine, I'm certain he can help  (four 1 nine) 2 5 8  0 five three 9 is his phone call or text ....if you call leave him a voice mail....best to text and ask him to ring you....tell him Aaron sent you

[55fairlane]

Brooks is in my shop as we speek.....do not use the governor...use the carb as a speed control....and if you try to contact Brooks....text and have him ring you....

[55fairlane]

The reason for the ¼ hole is the first time Brooks ran the engine, the compression pulled the intake valve right into the cylinder and broke the rings

[GordonL]

I did text Brooks but have not received a reply. The problem is in the carburation. When it runs it fires OK for a few seconds and then it fires with a loud explosion which I assume is burning off excessive fuel and then it finally floods out and stops. The needle valve/jet that he called for apparently is no longer available. I have tried several other carburetors and did have one run of about two minutes. I am thinking about trying a vapor carburetor. I have tried them in the past and I could never get one to work properly.

[55fairlane]

If you can get ahold of Brooks, send me an email indianaengineshow@gmail.com with your phone number and I will have Brooks ring you

Aaron

[55fairlane]

Can't i ment

[GordonL]

Actually you have answered my question about the intake so I really do not have further questions. I still cannot get the engine to run for any extended period of time. The problem is fuel/carburetor related so I have been playing around with that. Still one of the most frustrating engines that I have ever built. Thanks for your input.

[Admiral_dk]

It might sound stupid - but what height is the fuel tank compared to the Carburetor ?

Too high and you will flood the Engine in all cases where you don't have a float-chamber or injectors ....

Per           

[GordonL]

Fuel tank is lower than the carburetor.

[Zephyrin]

then it fires with a loud explosion

I would said that the ignition is too late...