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Engine basics => Engine set up tips => Topic started by: Dan Burns on January 24, 2010, 09:41:11 PM
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Hello again. Here I am with another basic question. What is the differance in using an R/C carb as opposed to one with a CL venturi? If an R/C carb performs o.k. on an aerobatic R/C plane, what is the advantage of a CL venturi on a stunter? I'm not talking world class compitition, just sunday flying. Thanx.......Dan
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I have used many RC engines on CL planes with no problems. I just wire the thing wide open and go fly. They are fine for fun flying.
Danny
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One advantage is the C/L venturi/needle is simple and reliable, fewer parts, less chance of air leaks, etc.
Simplicate and add lightness - can't remember who said it ... but it works!
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One disadvantage is that you can not use one of my Universal U/Tronics Control handles to control the throttle in flight!!!
See Vendors Corner.
I could not resist,
Clancy
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Just remember to wire the carb open. If the thing is closed it will be very hard to start. I worked for quite a while one afternoon trying to start one.
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Hello again. Here I am with another basic question. What is the differance in using an R/C carb as opposed to one with a CL venturi? If an R/C carb performs o.k. on an aerobatic R/C plane, what is the advantage of a CL venturi on a stunter? I'm not talking world class compitition, just sunday flying. Thanx.......Dan
For casual flying, it works fine. It's actually almost OK for competition on 2-strokes. It's pretty good on 4-strokes from what I have seen, but for whatever reason the engine seems to just change speed occasionally no matter how much stuff you lock down and seal up. It's not very much, but enough that it's bothersome. The solution is a regular venturi system like the Pat Johnston/UHP unit, or to sleeve the carb bore with something like a long piece of brass turbing that effectively cancel the rotating barrel.
Bottom line, if you aren't trying to win Open at the NATs, just wire it open and it will be just fine.
Brett
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Dan,
I'm working through the same issue as we speak. I've returned to C/L after 30 years of R/C and have several nice .45 sized R/C engines. I'm in the middle of an engine set up process now, having been grounded by the endless rain/mud. I found the timing to be too fast on the O.S. 45 and the lap times were crazy fast. I richened the mixture and went to a 4 pitch prop which made the lap times comfortable. But...the fuel burn was too much. I now have the carb linkage rigged so I can adjust the barrel opening to a reduced setting. When it stops raining, I plan to start over with the leaner setting and gradually close the barrel to get the launch RPM's down to a lower number. After I find a good flight RPM, I'll lock the barrel in that position. If that doesn't work, I'll consider the ventura, but I can't see anything wrong with this plan. Anyone have any thoughts?
Paul