Minijet J-3 instruction manual / blueprints
Moderator: Mike Everman
Minijet J-3 instruction manual / blueprints
I'm wondering if anyone has any instruction manuals, blueprints or info on the Minijet J-3 other than the two pages (page 9 and 13 from some book) mark posted back in '05. There doesn't seem to be much info floating around on this engine except the very basics. Thanks
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dynajetjerry
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- Location: Ohio, USA
Re: Minijet J-3 instruction manual / blueprints
rmckee,
I may have instructions for the Minijet but am not sure if it is the J-3. I'm not familiar with the specific designations, only being aware of 2 versions. Both were mfd. about 1946-48. The later one made use of a "spinner" in front of the intake and served to reduce flash-back during starting. It also reduced ram air entering the engine at high speeds; that air could reduce effective thrust.
Let me know and I'll try to track down the info I have. However, if you specify exactly what you wish to know, I may be able to supply it without the need for the mfrs. instructions. The basic needs include a pressure-tight tank of at least 6 ounces located as near to the engine as possible, correct plumbing, a continuous spark source, and a good auto tire pump. The latter should have its check valve (at the hose fitting at the pump,) and the tip in the threaded fitting removed. Their presence will restrict the flow of starting air.
Jerry
I may have instructions for the Minijet but am not sure if it is the J-3. I'm not familiar with the specific designations, only being aware of 2 versions. Both were mfd. about 1946-48. The later one made use of a "spinner" in front of the intake and served to reduce flash-back during starting. It also reduced ram air entering the engine at high speeds; that air could reduce effective thrust.
Let me know and I'll try to track down the info I have. However, if you specify exactly what you wish to know, I may be able to supply it without the need for the mfrs. instructions. The basic needs include a pressure-tight tank of at least 6 ounces located as near to the engine as possible, correct plumbing, a continuous spark source, and a good auto tire pump. The latter should have its check valve (at the hose fitting at the pump,) and the tip in the threaded fitting removed. Their presence will restrict the flow of starting air.
Jerry
Louder is always better.
Re: Minijet J-3 instruction manual / blueprints
I'm trying to find out more about the valves and how much they are suppose to be curved if at all. I've had them so the tip is about 1mm off the seat but it's not running well. I've got the latter one with the spinner.
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dynajetjerry
- Posts: 465
- Joined: Thu Jan 27, 2005 4:57 pm
- Antipspambot question: 0
- Location: Ohio, USA
Re: Minijet J-3 instruction manual / blueprints
rmckee,
The reeds are normally pretty flat. When clamped in place, their tips are very slightly open, perhaps your 1 mm. This clearance affects their ease of starting but not their running. If yours runs poorly, it will almost certainly be due to something other than this slight opening. The reeds must be smooth and flat so that they will seal under rather slight pressure of combustion. The engine might be running too lean or too rich but those are pretty obvious. Perhaps there are leaks in one or another gasket seals; either of those between sections of the pipe assembly could cause problems but they, too, would be pretty obvious as are frayed and leaking reeds or rough reed seats. If the pressure and fuel fitting leaks, on the bottom of the valve head, all sorts of other problems can appear including unsteady operation and very difficult starting. Maybe the fuel tank is not pressure tight or the pressure line or fuel line are not sealing. Without seeing and hearing it operate, I can make wild guesses only, as to the causes of poor operation.
Jerry
The reeds are normally pretty flat. When clamped in place, their tips are very slightly open, perhaps your 1 mm. This clearance affects their ease of starting but not their running. If yours runs poorly, it will almost certainly be due to something other than this slight opening. The reeds must be smooth and flat so that they will seal under rather slight pressure of combustion. The engine might be running too lean or too rich but those are pretty obvious. Perhaps there are leaks in one or another gasket seals; either of those between sections of the pipe assembly could cause problems but they, too, would be pretty obvious as are frayed and leaking reeds or rough reed seats. If the pressure and fuel fitting leaks, on the bottom of the valve head, all sorts of other problems can appear including unsteady operation and very difficult starting. Maybe the fuel tank is not pressure tight or the pressure line or fuel line are not sealing. Without seeing and hearing it operate, I can make wild guesses only, as to the causes of poor operation.
Jerry
Louder is always better.