Flapper AFM - Information required...
Discussion
Hi,
Can anyone tell me which direction (in or out) to weaken or richen the mixture on the flapper AFM.
Talking to people at Chatsworth on Sunday there was opinion which differed to my view.
My view was that the hex adjusting screw was only a "trim" the coarse setting being under the black plastic cover.
I also need to know if the adustment is fine, ie less than 1 turn to adjust CO 1% - 4% or a number of turns for similar adjustment, IIRC total adjustment is about 12 turns.
Is there a "basic" adjustment from which to start from? I've heard 2.5 turns out.
Brian (and a RED 350i)
Can anyone tell me which direction (in or out) to weaken or richen the mixture on the flapper AFM.
Talking to people at Chatsworth on Sunday there was opinion which differed to my view.
My view was that the hex adjusting screw was only a "trim" the coarse setting being under the black plastic cover.
I also need to know if the adustment is fine, ie less than 1 turn to adjust CO 1% - 4% or a number of turns for similar adjustment, IIRC total adjustment is about 12 turns.
Is there a "basic" adjustment from which to start from? I've heard 2.5 turns out.
Brian (and a RED 350i)
Anticlockwise will open up the idle air bypass port on the AFM, so the mixture will lean out. Clockwise will close down the bypass port, so the mixture will richen.
Only really effective at idle, since when driving , the engine is drawing a lot more air, so the proportion of the engine air charge bypassing the flap (ie going thru the bypass port) becomes insignificant.
2.5 turns out is probably a good place to start. Most (all?!?) flapper wedges "run a bit rich" at idle, so I wouldnt be too upset if you cant nail it with the idle mixture bypass screw.
Lucas 4cu is quite a basic efi system, the fuelling map can't be adjusted, so the only real change you can make is to play with the fuel pressure, which basically increases or decreases the fuelling across the whole map by approximately the same amount, so only worth doing if its out by the same amount at all bins (bin = single point/location in fuel map).
The idle speed can be adjusted, though, as can the idle mixture.
I would have to advise against tweaking the calibration ring inside the cover though. TVR diddled with them at the factory to approximately the correct fuelling (mines go the engine number scrawled on it). Without instrumentation and probably a dash of experience, you may do more harm than good. Not saying you're in any way incompetent, but intelligent diddling requires instrumentation and ideally a lambda probe & datalogger or a dyno.
Only really effective at idle, since when driving , the engine is drawing a lot more air, so the proportion of the engine air charge bypassing the flap (ie going thru the bypass port) becomes insignificant.
2.5 turns out is probably a good place to start. Most (all?!?) flapper wedges "run a bit rich" at idle, so I wouldnt be too upset if you cant nail it with the idle mixture bypass screw.
Lucas 4cu is quite a basic efi system, the fuelling map can't be adjusted, so the only real change you can make is to play with the fuel pressure, which basically increases or decreases the fuelling across the whole map by approximately the same amount, so only worth doing if its out by the same amount at all bins (bin = single point/location in fuel map).
The idle speed can be adjusted, though, as can the idle mixture.
I would have to advise against tweaking the calibration ring inside the cover though. TVR diddled with them at the factory to approximately the correct fuelling (mines go the engine number scrawled on it). Without instrumentation and probably a dash of experience, you may do more harm than good. Not saying you're in any way incompetent, but intelligent diddling requires instrumentation and ideally a lambda probe & datalogger or a dyno.
Additionally: If adjustment (even idle which I thought was my issue) doesn't do anything, take the adjuster fully out, clean it, put it back and adjust.... This was a good tip on here, as I had several MOTs in a row issues to be within the CO range (increasing idle to max allowed, low fuel pressure and a good run just did it everytime with a lot of risk). This took care of it and never had any issues again to adjust (CO and idle) and 3.5% is no issue anymore.
Seems that 4.0 to 4.5% is the best setting for power on flapper standard 3.5 V8.
Rob
Seems that 4.0 to 4.5% is the best setting for power on flapper standard 3.5 V8.
Rob
BrianTVR350 said:
Can anyone tell me which direction (in or out) to weaken or richen the mixture on the flapper AFM.
My view was that the hex adjusting screw was only a "trim" the coarse setting being under the black plastic cover.
Is there a "basic" adjustment from which to start from? I've heard 2.5 turns out.
Everything you ever wanted to know about the Rover SD1 Flapper AFM in my PDF available from here:My view was that the hex adjusting screw was only a "trim" the coarse setting being under the black plastic cover.
Is there a "basic" adjustment from which to start from? I've heard 2.5 turns out.
http://www.vintagemodelairplane.com/pages/Rover_Te...
Caution regarding adjusting the internals unless you feel confident of your intentions.
Thanks Ed, Rob and John...
The airflow meter has remained sealed for the last 15 years (since I took ownership) and I have no intention of opening it unless I have to....
Thanks for the info guys, in particular John, for the pointer to your documentation.
I need to spend a little time looking through the documentation, so I understand what is going on. May have to wait while it goes for MOT then I can have a twiddle while MOT man is having a brew.
Regards,
Brian (and a Red 350i)
The airflow meter has remained sealed for the last 15 years (since I took ownership) and I have no intention of opening it unless I have to....
Thanks for the info guys, in particular John, for the pointer to your documentation.
I need to spend a little time looking through the documentation, so I understand what is going on. May have to wait while it goes for MOT then I can have a twiddle while MOT man is having a brew.
Regards,
Brian (and a Red 350i)
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