John B
Well-Known Member
- Joined
- Jun 9, 2013
- Messages
- 222
I didn't want to hijack the other carb thread, but I also have been struggling with carb choice for the rebuild of my Sonerai IIL The airplane has been flying since 1992, but due to life, hasn't flown for about 10 years or so.
So I started off in 1992 with a POSa carb. After many hours fighting with it on the ground, including both modifying and machining custom needles, and then 10 or so flight hours in, I had finally had enough. I felt so highly of my experience with the POSa that it came off and went into the garbage can.
I then tried a Solex 34 PICT carb that came off of an actual VW Beetle and I believe it would have worked great on about 1835 or smaller displacement, but just didn't flow enough for my 2276cc engine. It would also have needed carb heat.
I wound up with a Dellorto 2 barrel side-draft carburetor that was infinitely tuneable and it worked great. It should have had carb heat but I instead ran it where it is drawing air that had already been through the cylnders. At this point the airplane has sat for several years and the last fuel it had in it was auto fuel. Needless to say the carb is pretty much crap now since I can't get parts for it anymore. This carb worked well, but the two carb throats weren't ideal with one throat feeding the left bank and the other feeding the right bank. I probably could ahve rebuilt this carb by buying NOS parts for a couple hundred dollars but I decided to try something different.
I have seen the AeroInjector in person and it is a nice looking piece of equipment. Well made, and I do believe that even though the basic theory of operation is the same as the POSa that the problems the POSa had would likely be solved. It does have one issue that the POSa had that I never did like and that is the fact that if the fuel valve is on fuel is going somewhere. I just would really prefer a carb that doesn't leak. I still am considering this a fallback option, but...
The Great Plains Zenith carbs are fine, but they are a basic venturi style carb that can make ice and they really have no benefit over venturi type carbs. I have a side draft Harley Bendix carb and if I were to use an ice-maker carb I'd probably use this one.
To combat the icing issue while still having a flat equipped carb, I decided to give a Keihen CV40 constant velocity carburetor as used on early 2000's Harley Davidson motorcycles a try. The benefit of the CV carbs is that they are a variable venturi constant velocity carburetor and this supposedly makes them less prone to carburetor icing, which was always in the back of my mind. Being a vacuum operated CV carb they are also somewhat altitude compensating. I have the new intake fabricated and have the engine running well from idle to about 2400 rpm. Past 2400 rpm it is leaning out too much and I have parts on order to combat this. Hopefully this will get me going soon. If anyone has Keihen CV40 tuning experience let me know. I think I have it pretty well figured out but maybe talking to someone who has specific knowledge about the idiosyncrasies of tuning this carb would probably help.
Thanks
John Brannen
So I started off in 1992 with a POSa carb. After many hours fighting with it on the ground, including both modifying and machining custom needles, and then 10 or so flight hours in, I had finally had enough. I felt so highly of my experience with the POSa that it came off and went into the garbage can.
I then tried a Solex 34 PICT carb that came off of an actual VW Beetle and I believe it would have worked great on about 1835 or smaller displacement, but just didn't flow enough for my 2276cc engine. It would also have needed carb heat.
I wound up with a Dellorto 2 barrel side-draft carburetor that was infinitely tuneable and it worked great. It should have had carb heat but I instead ran it where it is drawing air that had already been through the cylnders. At this point the airplane has sat for several years and the last fuel it had in it was auto fuel. Needless to say the carb is pretty much crap now since I can't get parts for it anymore. This carb worked well, but the two carb throats weren't ideal with one throat feeding the left bank and the other feeding the right bank. I probably could ahve rebuilt this carb by buying NOS parts for a couple hundred dollars but I decided to try something different.
I have seen the AeroInjector in person and it is a nice looking piece of equipment. Well made, and I do believe that even though the basic theory of operation is the same as the POSa that the problems the POSa had would likely be solved. It does have one issue that the POSa had that I never did like and that is the fact that if the fuel valve is on fuel is going somewhere. I just would really prefer a carb that doesn't leak. I still am considering this a fallback option, but...
The Great Plains Zenith carbs are fine, but they are a basic venturi style carb that can make ice and they really have no benefit over venturi type carbs. I have a side draft Harley Bendix carb and if I were to use an ice-maker carb I'd probably use this one.
To combat the icing issue while still having a flat equipped carb, I decided to give a Keihen CV40 constant velocity carburetor as used on early 2000's Harley Davidson motorcycles a try. The benefit of the CV carbs is that they are a variable venturi constant velocity carburetor and this supposedly makes them less prone to carburetor icing, which was always in the back of my mind. Being a vacuum operated CV carb they are also somewhat altitude compensating. I have the new intake fabricated and have the engine running well from idle to about 2400 rpm. Past 2400 rpm it is leaning out too much and I have parts on order to combat this. Hopefully this will get me going soon. If anyone has Keihen CV40 tuning experience let me know. I think I have it pretty well figured out but maybe talking to someone who has specific knowledge about the idiosyncrasies of tuning this carb would probably help.
Thanks
John Brannen