Inline dual four Holleys

[StanJ]

Originally Posted by Michael C Henry

I have the Quick Fuel Technology secondary metering plates in both carbs. I'm notching the primary floats to accept vent whistle. It has been long enough that I have forgotten which epoxy to use to cover and seal the notched area in my Nitrophil floats. Primary carb had #65 primary jetts and #68 secondary jets. At 2500 RPM in neutral and progressive linkage, probably didn't even crack the secon carbrueter.
Any more reccamendation on leaning the idle out on this thing?

Michael, what size are the idle circuit feed restrictions in your Quick Fuel Technology metering plates? These are adjustable; as I recall QFT uses a #6-32 thread screw-in restriction there. I can’t recall QFT’s baseline idle feed orifice size in this part from memory, but your application should be quite happy with something around .032” dia.

As for the idle circuitry in the primary metering block, look at this picture:



The idle circuit feed restrictors in your metering blocks are likely located in the positions marked “1”, although depending on when your carburetors were manufactured they might possibly be underneath the outermost well caps on the top of the metering block. In any case, they should ideally be relocated the positions marked “2a” and “2b”. This positioning allows the idle circuit to respond more quickly to changes in throttle position and engine fuel demand, thereby allowing the use of a smaller orifice size. As I mentioned earlier, your primary metering blocks can easily be machined to accept screw-in restrictors in this position. I’d recommend starting out at .026” or .028” orifice size, which is considerably “cleaner” than the .032” orifice you have now.