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Yes, I know you can't run a Lambda head absent the FV without making adjustments but I'm trying to determine what the actual physical differences are between the Lambda and non-Lambda heads. The only thing I can come up with is the orifice that supplies fuel into the lower chambers. This is what the Bosch tech manual says:
"In order to be able to vary the pressure in the lower chambers, these are decoupled (in contrast to the conventional K-jetronic fuel distributor) from the primary pressure. Decoupling is by means of a fixed throttle. A further throttle connects the lower chambers with the fuel return. "
The "fixed throttle" is the orifice between the system pressure existing under the plunger and the lower chambers. The "further throttle" is the FV.
In order for the FV to drop the lower chamber pressure the fixed orifice has to be small enough to restrict the flow going into the lower chambers as the FV dumps fuel from the lower chambers into the return, otherwise the pressure in the lower chambers will not drop.
With the FV disabled, as the plunger moves up and down with changes in air flow the diaphram has to move up and down to force fuel into and out of the lower chambers. With the fixed orifice in place the flow entering and exiting the lower chambers will be restricted.
So simply opening up that orifice should allow the lambda head to operate just like a non-lambda head.
But adjustments to the spring pressure in the differential valves and or changes to the control pressure will still be necessary to get the correct AFR with the FV out of the picture.
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