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Gentlemen,
The 1/8th Galloway is now running. I had built the whole engine as per the plans and posted my progress in another thread. When I built the carb I was skeptical of the design and from some information from another fellow found that when it came time to get it running the information was correct. This required a redesign and build of the carb.
On the initial attempts to get the engine running I could only get it to pop now and then. There were so many issues, carb, igniter, and what seemed like a whole new problem, the compression, I was really getting down. Although the boring and honing of the cylinder was perfect and I had made 2 rings for the piston instead of the 1 in the drawing it seemed like the compression was very low. This meant another disassembly to check valve sealing, which were in fact fine. I then rehoned the bore which required a new piston and rings. Once completed and reassembled the compression still wasn't like the bigger engines. When the engine was flipped over and would come up against the compression it would stop but just didn't seem right. Kind of a seat-of-the-pants type thing. I didn't calculate the compression ratio so it's possible that it's low right from the very start.
The next issue was the igniter. Although I knew it would work on the bench I wasn't sure of what was going on in the engine so to eliminate that problem, for the time being, I made up parts to install a Hall transistor and magnet disc on the outboard side of the engine. This would be used in conjunction with one of my S&S transistorized ignitions. For spark a made another disc the same diameter as the igniter body and tapped it for an 8-32 spark plug that I had made for one of my other engines.
The Galloways all have the fuel tank sitting higher than the carb, this one also. On the other engines they use a Lunkenheimer type carb with an internal valve to stop the fuel flow but this one is a simple mixer type carb and here again I didn't like the idea of the gas forcing it's way past the needle so a redesign of the carb was in order. That took a day of drawing and building.
With all the new elements assembled it was time to make the second attempt at running the engine. Flipping by hand didn't seem to produce any results so I used one of my 12 volt airplane engine starters. The engine popped but as I spun the engine over another problem surfaced. The lockout lever for the pushrod would engage way too easily so I had to make up another couple of springs until it seemed like I was in the ballpark.
Back to the third attempt.
Carb open 1/2 turn, ignition on, hit the starter and this time I got a handful of pops.
Every time it would stall I would choke the carb with my finger and the engine would make the normal handful of pops which told me it needed more fuel so I kept opening the carb until it finally kept running. The new carb has a sewing needle for the needle so the taper is very long owing to the greater need for adjustment.
The engine now starts and runs very well. The video doesn't show it but it will even start by hand.
With all the extra work rehoning the bore and making a new piston and rings the compression isn't much greater than the intial build. It does seem to bump harder against the compression stoke so I suspect it's just in the design.
With all that said here's a link to the video.
[ame]http://youtu.be/mby5cKT0Cg4[/ame]
George
The 1/8th Galloway is now running. I had built the whole engine as per the plans and posted my progress in another thread. When I built the carb I was skeptical of the design and from some information from another fellow found that when it came time to get it running the information was correct. This required a redesign and build of the carb.
On the initial attempts to get the engine running I could only get it to pop now and then. There were so many issues, carb, igniter, and what seemed like a whole new problem, the compression, I was really getting down. Although the boring and honing of the cylinder was perfect and I had made 2 rings for the piston instead of the 1 in the drawing it seemed like the compression was very low. This meant another disassembly to check valve sealing, which were in fact fine. I then rehoned the bore which required a new piston and rings. Once completed and reassembled the compression still wasn't like the bigger engines. When the engine was flipped over and would come up against the compression it would stop but just didn't seem right. Kind of a seat-of-the-pants type thing. I didn't calculate the compression ratio so it's possible that it's low right from the very start.
The next issue was the igniter. Although I knew it would work on the bench I wasn't sure of what was going on in the engine so to eliminate that problem, for the time being, I made up parts to install a Hall transistor and magnet disc on the outboard side of the engine. This would be used in conjunction with one of my S&S transistorized ignitions. For spark a made another disc the same diameter as the igniter body and tapped it for an 8-32 spark plug that I had made for one of my other engines.
The Galloways all have the fuel tank sitting higher than the carb, this one also. On the other engines they use a Lunkenheimer type carb with an internal valve to stop the fuel flow but this one is a simple mixer type carb and here again I didn't like the idea of the gas forcing it's way past the needle so a redesign of the carb was in order. That took a day of drawing and building.
With all the new elements assembled it was time to make the second attempt at running the engine. Flipping by hand didn't seem to produce any results so I used one of my 12 volt airplane engine starters. The engine popped but as I spun the engine over another problem surfaced. The lockout lever for the pushrod would engage way too easily so I had to make up another couple of springs until it seemed like I was in the ballpark.
Back to the third attempt.
Carb open 1/2 turn, ignition on, hit the starter and this time I got a handful of pops.
Every time it would stall I would choke the carb with my finger and the engine would make the normal handful of pops which told me it needed more fuel so I kept opening the carb until it finally kept running. The new carb has a sewing needle for the needle so the taper is very long owing to the greater need for adjustment.
The engine now starts and runs very well. The video doesn't show it but it will even start by hand.
With all the extra work rehoning the bore and making a new piston and rings the compression isn't much greater than the intial build. It does seem to bump harder against the compression stoke so I suspect it's just in the design.
With all that said here's a link to the video.
[ame]http://youtu.be/mby5cKT0Cg4[/ame]
George
