RE: Setting up an OS 1.60, cline, bisson pitts, 18x6w
The instructions state the second way where the regulator is between the HSN and the carb which makes perfect sense because the ventui action of the carb will cause the the regulator to flow fuel as the carb needs it, while the HSN limits the whole thing on the high end. Theory of operation is simple, the regulator has a plunger that taps on a float like valve that opens the intake side. As the carb ventui sucks on the output side, it causes the regulator to pass a little fuel. So having the regulator next to the carb is pretty much the same as having the clunk 1/2" from the carb, but without any exhaust pressure pushing it. This would work fine if the carb wasn't sucking too much fuel in the midrange.
Now I did try it the other way with the regulator before the HSN and that did transistion better, but I couldn't get the engine to run rich even with the HSN all the way out, so the carb signal wasn't good enough to draw the fuel though the HSN.
I wish this carb had a seperate idle circuit, then this wouldn't be a big deal.