PCV Vacuum Source

[Stumper]

Bear in mind that the idle fuel feed circuits MUST BE CALIBRATED to accomodate the additional air entering the engine. There are hydrocarbon energy (as oil and fuel vapors) in the PCV system that will also effect the idle and off idle fuel transition circuits that will need to be determined. If, the additional air is not accommodated, a large flat spot, almost to the point of a lean stall may develop. Likely, the static and dynamic ignition curve will need to be developed. Just be aware that it is not as simple as drilling the carb to accomodate a hose connection. Just my opinion of course....
BOB RENTON

Very good point Bob. I admittedly was not thinking in that level of detail. Makes sense that some tuning would be needed. Not sure I can grasp the need to adjust the timing curve tho?

 

[RJRENTON]

Very good point Bob. I admittedly was not thinking in that level of detail. Makes sense that some tuning would be needed. Not sure I can grasp the need to adjust the timing curve tho?

REGARDING the timing curve.....IMO, with a leaner (due to the introduction of PCV air) fuel ratio, its possible that slightly more static and a quicker (rate of change of change) centrifugal advance will benefit the off idle operation. The idle and off idle fuel transition circuits are not controlled by the primary jets and metering rods, in a Carter carb (and Edelbrock aka "EDDY" or Weber clones) but in the primary booster venturii assemblies. In addition, the position of the off idle transition slots, in the carb's primary throttle bores and possibly the corresponding throttle plate milled peripheral slots affect the when and lenth of time fuel feed occurs. USUALLY, these parameters by determined in the design phase and not some "seat of pants" guesses......anyway you can experiment...... just my opinion of course.
BOB RENTON