Author Topic: Vertical hit and miss engine  (Read 10183 times)

Offline Art K

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Re: Vertical hit and miss engine
« Reply #240 on: September 06, 2019, 03:31:14 AM »
Brian,
Good to hear that you dieted hard and lost 30Ibs, that is impressive. If I lost that much I'd weigh about what I did when I graduated from high school. I enjoyed the video of the hit & miss at work. I could picture you doing that half the day watching it go up & down. :lolb:
Art
« Last Edit: September 08, 2019, 11:09:20 PM by Art K »
"The beautiful thing about learning is that no one can take it away from you" B.B. King

Online Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #241 on: September 08, 2019, 05:32:29 PM »
After much playing about with this engine, under both load and no load conditions, I have come to notice this phenomenon that I have seen before on other hit and miss engines. When the engine is running very slowly, with a good number of "misses" between "hits", the fuel in the line running to the carburetor wants to all run back down in to the tank during long "miss" cycles. Then when it finally does "hit" again, there is no fuel at the carb and the engine stops. I use clear neoprene gas line, and I can see it doing this. The answer of course is my venerable one way valve, as shown in the .jpg. This one way valve only works well in the vertical position, and the best location is immediately below the carburetor fuel inlet. Experience has shown that a 3/32" diameter ball is the optimum size. If the ball is larger, the venturi vacuum from the carburetor may not be strong enough to lift the ball consistently.
« Last Edit: September 08, 2019, 05:36:46 PM by Brian Rupnow »

Online Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #242 on: September 08, 2019, 08:17:17 PM »
That fixed it!! You can see it setting directly below the carburetor fuel inlet. (there really isn't much to see, because the gas-line pushes on from both ends of it). Now when the engine is on "miss" cycles, the fuel doesn't run back from the carburetor at all. The engine starts a lot easier too, with much less manual choking.--Also of interest to some will be the gear reducer with the piece of tape on the output shaft. I built that reducer about ten years ago, using gears from a couple of dead electric drills. It has an 8:1 overall ratio. That reducer was built back before I purchased my own complete set of 24DP gear cutters.


Offline Ye-Ole Steam Dude

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Re: Vertical hit and miss engine
« Reply #243 on: September 09, 2019, 09:05:08 AM »
Hello Brian,

Great job on the overall design and build on this engine. Watching the last video I really like the sound when running without the "miss", sounds smooth and strong.

Have a great day,
Thomas

Online Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #244 on: September 11, 2019, 10:19:09 PM »
One of the people building the engine from my plans has discovered an error in the con rod drawings. I will be sending new corrected drawings of the con rod and cap out to all who purchased the plans later this evening.---Brian

Online Brian Rupnow

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Re: Vertical hit and miss engine
« Reply #245 on: September 11, 2019, 11:19:16 PM »
For those of you who are building this engine-----The crankshaft endplay ends up being controlled externally by the ignition cam on one side and by the small bevel gear on the other side. My original plan was to have it controlled on the inside by having the two registers on each side of the crank-throws riding against the ball bearings. There are enough accumulated tolerances to make this a very iffy thing. The real story is that the crankshaft is centered by the con rod, which is positioned by the piston, riding in the bore of the cylinder which is bolted to the crankcase.  Originally I had made no provision on the crankshaft for the sideplate gaskets. Then when I went to assemble everything and seen exactly how the crankshaft was being centered as explained above, I was glad that I had left that
.030" clearance on each side of the crank throws to the ball bearings. You may find that you have to put a small spacer washer between the small bevel gear and the shoulder on the crankshaft. That is something that you won't know if you need or not until final assembly.