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What you describe your engine is doing is exactly what I and others have witnessed. When I researched for info, I found that Lycoming specifies certain O-320 engine models for different aircraft. Going down the list, I found only one experimental aircraft - Lancair 320. That engine model was O320-A2B. Going to their Engine Model specifications list - this engine specifies what is called a -32 carb. I called Precision to find out what that carb is all about and they explained very precisely. It is a carburetor set up deliver more fuel across the entire airflow range. The Lancair 320 has a low back pressure exhaust system compare to certified aircraft with mufflers. As such it needs more fuel.
It is NOT, just a larger jet size. It has a very specific nozzle, and the fuel flow regulator (the brass doohickey in the base of float bowl), is clocked at a different angle relative to the fuel/air mixture rod.
These features are not something you or your repair shop can change on your existing carb.
Many people have simply bored out the jet on their existing carbs and were able to get satisfactory results. But, according to Precision, the atomization will not be ideal. Often it leads to uneven EGTs.
On Feb 24, 2020, at 6:59 AM, Jim Evans <jevansez@...> wrote:
Gary: I saw your post on the carb change. I have had similar problems with mine for years and suspected carb issues. Can you explain what overheating symptoms you witnessed as a result of the wrong carburation? Mine overheats on CHT almost immediately from takeoff through climb. After leveling off in cruise and given time to cool down, the engine runs pretty much normal. Any input would be appreciated.
Hope you have a great day.
On Sun, Feb 23, 2020 at 11:11 PM Gary Hunter via Groups.Io <firstname.lastname@example.org
Make sure you have the correct carburetor. For our application with free flowing exhaust you need to use the following carb.
Model # 10-3678-32
Lycoming part # 72394
This carb unusual set up to provide extra fuel flow.
I have seen switching to this carb solve many cooling issues.
I’m running a160hp 0-320 and switched to armpit scoops for cooling.
On Feb 23, 2020, at 4:50 PM, Afif Saybe <afif@...> wrote:
I recently factory overhauled my O320E2G Long EZ and upgraded from 150-160HP. I've done a couple fo flight and I've noticed higher engine temperatures (in the 420+ degF) than my previous configuration. I have a conventional updraft configuration in my LEZ and I'm wondering if its time to modify the cowls for additional cooling. I'm also planning of replacing the straight pipes too.... Attached are pictures of my LEZ with current cowlings....Would love to hear of experiences of LEZ with 160HP engine and temperatures range operation....Thanks in advance!
James W. Evans Jr.
Tappahannock - Essex County Airport
1450 Aviation Rd.