Sport Jett carb and crankcase pressure rather than pipe pressure
05-18-2005, 06:09 AM
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Sport Jett carb and crankcase pressure rather than pipe pressure
I had planned to try using an Iron Bay regulator with a Sport Jett 46 last year but I never did. Bob27s and I mentioned this is the following thread.
http://www.rcuniverse.com/forum/fb.a...n%2CBay%2CJett
Bob27s (or anyone else using a Sport Jett carb),
Two questions:
Did you ever test the smaller Jett engines with an Iron Bay (or Cline) regulator?
Do you think that crankcase pressure (through the one way check valve) would be usable instead of pipe/muffler pressure for pressurizing the fuel system when not using an Iron Bay (or Cline) regulator?
http://www.rcuniverse.com/forum/fb.a...n%2CBay%2CJett
Bob27s (or anyone else using a Sport Jett carb),
Two questions:
Did you ever test the smaller Jett engines with an Iron Bay (or Cline) regulator?
Do you think that crankcase pressure (through the one way check valve) would be usable instead of pipe/muffler pressure for pressurizing the fuel system when not using an Iron Bay (or Cline) regulator?
05-18-2005, 10:16 AM
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RE: Sport Jett carb and crankcase pressure rather than pipe pressure
If you use a regulator, you want to use crankcase pressure. You can not use crankcase pressure without the regulator of some kind, unless you are running wide-open the whole time (like a CL speed, FAI or F-1 engine, and some FF engines).
My "unofficial' tests with the SJ46 I have with the ironbay regulator showed that it does work. Although, it seems to be sensitive to where you mount it. I found it best mounted between the needle and the carb inlet. Having said that, I have seen some issues where at higher rpms the reed seems to get into a resonance or something, and the engine acts real goofy. Considering they use this on fan engines, that should not have come into play. So my initial impression is I have an inconsistant situation. Needs more experimenting time - so far I devoted about 1 afternoon to playing with it.
From what I have seen, pipe/muffler pressure is inconsistant and insufficient to make their ther Cline or Iron Bay device work properly. Crankcase pressure with a check valve is a must. Make sure you wrap the fuel tank with some glass-reinforced packing tape (or similar) to keep it from expanding too much (And possibly rubbing/wearing on a structure... or splitting).
Best I can say, is try either regulator. Run it on the bench. See how things work. Any data you can add to my collection would be greatly appreciated. Worst comes to worse, you put a 6/32 screw in the backplate where the pressure fitting was
As soon as wife/baby/kid/t-ball/soccer stuff mellows out a bit, I can try and get some more run time.
Bob
My "unofficial' tests with the SJ46 I have with the ironbay regulator showed that it does work. Although, it seems to be sensitive to where you mount it. I found it best mounted between the needle and the carb inlet. Having said that, I have seen some issues where at higher rpms the reed seems to get into a resonance or something, and the engine acts real goofy. Considering they use this on fan engines, that should not have come into play. So my initial impression is I have an inconsistant situation. Needs more experimenting time - so far I devoted about 1 afternoon to playing with it.
From what I have seen, pipe/muffler pressure is inconsistant and insufficient to make their ther Cline or Iron Bay device work properly. Crankcase pressure with a check valve is a must. Make sure you wrap the fuel tank with some glass-reinforced packing tape (or similar) to keep it from expanding too much (And possibly rubbing/wearing on a structure... or splitting).
Best I can say, is try either regulator. Run it on the bench. See how things work. Any data you can add to my collection would be greatly appreciated. Worst comes to worse, you put a 6/32 screw in the backplate where the pressure fitting was
As soon as wife/baby/kid/t-ball/soccer stuff mellows out a bit, I can try and get some more run time.
Bob
