Hi all
I started this thread way back when. I have some info that might help builders of this model. As you know I redid all the drawings for Ministeam and they now own them. They asked me to get their engine converted from the spark ignition to an ignitor, and using their carburator with the elevated fuel tank. Thanks to the excellent work of Gary on trying the same thing and providing me information I experimented further and got everyting working. The engine, ignitor, and carburator were available to me from Ministeam after it was delivered to them and they got it painted. The original builder (George Britnell) just decided to use a spark plug and his carburator design.
No modifications to the ignitor, or fuel tank.
The changes to carburator/mixer are as follows.
The nozzle as shown on the drawing needs the jet hole changed to a
a #79 (.0145). The feed hole from the other end needs to be a #76 (.020). Depending on how you machined the main casting you want the jet end to be .020 short of the center line of the air chamber. To maintain contentricity the 8-32 must be single point threaded on the lathe.
The needle needs a more change. Ideally you would want more than the 40 threads to the inch, if you can make your own tap get it up to 100 or more. On my engine I have a working lunk with 112 threads.
What you are going to do is get a #10 needle (.018 diameter). The threads need to be .570 long under the head. You need to have the needle end sticking out .230. Make the cutoff needle about .440 or so. You then drill a #75 (.021) hole in the end or the needle holder the depth to have the .230 sticking out. In the case above drill .210 deep. Again you need to do this in one setup - drill the hole, turn it down .570 and single point the 5-40. Do not use the jam nut called out, instead make a spring so as to keep tension on the threads. Using 640 loctite (slow setting 30 min) put the needle in the needle holder. Then clean threads no excess loctite. Thread into the casting and into the nozzle carefully not real tight just snug. Let sit overnight.
You now have the carburator/mixer that is on the engine in the video. You MUST turn the mixer off when engine is stopped or it will drain the tank! You could put a shut off valve on the tank - better solution.
This setup floods easily, so starting is a bit tricky. I choke it with a turn or two, shut the valve off and kick it on. On this engine it takes 2 - 2 1/4 turns to run nice.
One other issue for builders. When you press the sleeve into the use loctite 640, it is for a press fit and seals well. Also use this when inserting cylinder into the Base. The slow setting property lets you align the cylinder perfectly.
Here is the Ministeam engine :
[ame]https://www.youtube.com/watch?v=LU0e4kePvxs&feature=youtu.be[/ame]
Ministeam does not have the updated prints yet, I felt getting this out might help. I will be providing updated prints to them in a week or so, and I am sure it will take about a month before they get it incorporated into their system. So do not call them for a bit for an updated carburator print.
Bob
