Over Heating???
08-30-2003, 10:42 AM
#2
Senior Member
Over Heating???
Star..
I don't have a specific temperature to offer up, but generally...with an ABC (or any engine) overheating can be caused by too lean a needle setting, too big of a prop, etc, etc, etc.
Your question is rather broad, so this is the best I have.
'Race
I don't have a specific temperature to offer up, but generally...with an ABC (or any engine) overheating can be caused by too lean a needle setting, too big of a prop, etc, etc, etc.
Your question is rather broad, so this is the best I have.
'Race
08-30-2003, 03:19 PM
#3
My Feedback: (90)
Over Heating???
If your flying and you hear the motor start to sag your overheating and should cut the throttle and land and reset the needle valve.
after a flight momentarely touch the head of the engine you. If you can't then your running too hot and need to richen the N.V.
the info in the previous post is also correct . The worst is too much prop or too much pitch.next a fuel that has too little oil.
after a flight momentarely touch the head of the engine you. If you can't then your running too hot and need to richen the N.V.
the info in the previous post is also correct . The worst is too much prop or too much pitch.next a fuel that has too little oil.
08-30-2003, 09:00 PM
#4
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Over Heating???
Star:
I try to keep my engines in the 250F-300F range. Up to 350F is acceptable, below 250F is too cold and can lead to idle problems.
You can have a running temp in the 300F range and still find it drops to 210-220 at idle. It will tend to die if it does.
Bill.
I try to keep my engines in the 250F-300F range. Up to 350F is acceptable, below 250F is too cold and can lead to idle problems.
You can have a running temp in the 300F range and still find it drops to 210-220 at idle. It will tend to die if it does.
Bill.
08-31-2003, 03:31 PM
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Over Heating???
The question asked is associated with a small? percantage of the GMS.47 engines sold. The majority? of these engines run fine and are very strong performers, although requiring some degree of sealing of the carb and backplate to cure air leaks.
The problem engines run entirely too hot and will typically go hot and die a couple of minutes into flight, EVEN WHEN THE CARB IS PROPERLY NEEDLED. The richness of the carb seems to make no difference in this problem. Neither does the size of the prop nor the type of flying nor the type or brand of fuel.
The pinch of the liner does not seem excessively tight, as I have seen tighter that performed well.
Some have dissasembled these engines and found varnish/carbon build-ups on the sides of the pistons and assumed this is the problem. My supposition is this is a result of the problem and not the cause, as I have seen these engines exhibit the problem when new from the box.
Thinking this was a problem of excess compression I have installed three head shims on one which changed nothing. I have one GMS.47 which runs well and strong, but still exhibits the extremely hot condition. After landing it is too hot to even try the touch test even though it was leaving a nice white smoke trail while flying and would jump 300 RPM when the fuel line was pinched.
My contention is this is a QC issue pertaining to the port timing but I am not an engineer and probably not entitled to make these conclusions.
Still looking for a solution.
Cajun
The problem engines run entirely too hot and will typically go hot and die a couple of minutes into flight, EVEN WHEN THE CARB IS PROPERLY NEEDLED. The richness of the carb seems to make no difference in this problem. Neither does the size of the prop nor the type of flying nor the type or brand of fuel.
The pinch of the liner does not seem excessively tight, as I have seen tighter that performed well.
Some have dissasembled these engines and found varnish/carbon build-ups on the sides of the pistons and assumed this is the problem. My supposition is this is a result of the problem and not the cause, as I have seen these engines exhibit the problem when new from the box.
Thinking this was a problem of excess compression I have installed three head shims on one which changed nothing. I have one GMS.47 which runs well and strong, but still exhibits the extremely hot condition. After landing it is too hot to even try the touch test even though it was leaving a nice white smoke trail while flying and would jump 300 RPM when the fuel line was pinched.
My contention is this is a QC issue pertaining to the port timing but I am not an engineer and probably not entitled to make these conclusions.
Still looking for a solution.
Cajun
08-31-2003, 04:08 PM
#6
My Feedback: (90)
Over Heating???
Cajun,
There are a few things concerning cooling more then compression or pinch.
The biggest thing is the fit of the liner to the case. Those that are the most difficult to remove are the coolest running. That liner absorbs a lot of heat and really needs a lot of area to get rid of it You cannot depend on just the head ot excess oil to dissipate heat the whole motor has to do it's part. Cheaply made or motors that are not made to exacting tolerance always have a loosely fitted liner.
Another thing is that these motors are usually made to run on low or no nitro. Yes, you can shim the head to run higher nitro but you have also changed the combustion chamber and usually requires at least some work on plugs and prop to maxamize the performance of the motor.
Unfortunately the apparent simplicity of these motors makes a lot of people think that they should be idiot proof. Sixty years after the first motor,the brown Jr, we are still trying to get it right.
There are a few things concerning cooling more then compression or pinch.
The biggest thing is the fit of the liner to the case. Those that are the most difficult to remove are the coolest running. That liner absorbs a lot of heat and really needs a lot of area to get rid of it You cannot depend on just the head ot excess oil to dissipate heat the whole motor has to do it's part. Cheaply made or motors that are not made to exacting tolerance always have a loosely fitted liner.
Another thing is that these motors are usually made to run on low or no nitro. Yes, you can shim the head to run higher nitro but you have also changed the combustion chamber and usually requires at least some work on plugs and prop to maxamize the performance of the motor.
Unfortunately the apparent simplicity of these motors makes a lot of people think that they should be idiot proof. Sixty years after the first motor,the brown Jr, we are still trying to get it right.
