Quote:
Originally Posted by 88tlc
Dougal,
thanks for more explanation, it sounds like you have some key knowledge as to what is actually happening on the inside of the pump. I have not taken these apart, and do not know what reaction there is to the ALTCOMP/ANEROID getting more pressure. but I am trying to wrap my mind around some key facts, and the two devices in my mind work the same. one though is for no turbo, one is for turbo.
Something above seems inconsistent. What I think we are comparing is:
ALTCOMP set up without boost, only ambient pressure. Max fuel is delivered at max pressure which is sea level. so more pressure, pushing, should mean more fuel?
Aneroid - set up with boost pressure. Again, max fuel is delivered at Max pressure, in this case max boost pressure. max pressure, pushing, means more fuel?
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The operation is of the two devices is simply reversed.
The aneroid uses contained air pressure to withdraw the rod and allow more fuel.
The altitude compensator uses contained air pressure to push on the rod and reduce fuel.
To facilitate this difference, the aneroid is offset by around 40mm to the side to allow room for an adjustable rocker. The entire thing overhangs the side of the governor.
It's not a good picture, but I can't get a good photo of this area in my truck so a drawing will have to do.
The large hole shown in the aneroid mount is the location of the plunger rod. It extends through the governer housing to restrict the movement of the cam which allows rack travel. The exact same cam on the outside of the pump with the maximum fuel screw on it.
I have pulled apart both of my pumps with the intention of swapping the aneroids between them. In that I suceeded, but the drive gear bore size was different so I could not use the newer style pump.
It is entirely possible to make an aneroid from an altitude compensator, but it'll involve pulling it apart, ensuring the front side is sealed and fitting a boost line to the front chamber, not the rear one with that nipple on it.