Quote:
Originally Posted by Ed Wright
Just curious, wondering (surely this has been tested) about the flow rate difference through a given size needle & seat assy (say a .125" or .150" dia orfice in the seat) with various i.d. fuel hoses, all much larger I.d. than the orfice in the needle & seat? A Quadrajet only has one, with a small float bowel for all four jets. I'm guessing the most difficult carb to keep full enough? Kinda seems like if the fuel line/hose I.d. was larger than that one orfice, a larger line would not help. Pretty interesting, thinking how a much larger line would alter the flow rate through the seat orfice.
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I worked for an aftermarket manufacturer once upon a time and we did test some different configurations using an orifice attached to a flow meter.
We were attempting to qualify the differences between needle and seat area and fuel pressure with respect to fuel volume. We also tested differing configurations before and after the secondary regulator. It's been so long ago now that I don't recall the specifics of that test, but I do remember a fondness for bypass style systems. It seemed that the less total area that you flowed through needed a bypass to keep the secondary regulator functioning.
If the fuel system was primarily laminar flow like fuel injection, fuel line area and orifice area can be closer than a carbureted system. Since a carburetor is essentially a siphoning device, fuel flow through the boosters and calibration are affected by the level of fuel available in the bowl(s). When the needle(s) open the bowl needs to be refilled as rapidly and smoothly as possible.
If your using alcohol with a carburetor the pump essentially overcomes the regulators ability to control pressure at some engine RPM. The needle and seats are the restrictions but volume is increased with the excess pressure.