Recently converted from EFI to carburetor. Engine is ZZ502. Idle and transition is rich, running 11 to one AFR or so. Transition slot below throttle place is a tiny square on the primary. Idle speed set with the secondary. With some careful adjustments on the four corner idle, able to get idle to about 13.5 to one plus or minus. Super sensitive on the idle adjustment. 1/16th of a turn goes from 13.5 to 15.0.

Still rich on the transition coming up to when the primary begins to work. The Idle Fuel Restrictors measured at .036. OEM metering blocks, so IFRs are pressed in. After doing some reading, have decided to try reducing the IFR slightly to lean out the transition fuel and make the idle adjustment screws less sensitive. Using the tried and true wire system.

I stripped two pieces of automotive wire. The stands of one measured at .015 and the strands of the other measured at .012. According to the arithmetic, the .012 wire would reduce the IFR from .036 to effectively .034. If that doesn't do the trick, I will try the .015 wire that should reduce the IFR to .033.

Once I know the target size, I can figure out how I want to permanently change the IFR. I am thinking about drilling it out of the present location, tapping and inserting a 6-32- 1/8 or 3/16 long brass hex plug in its place and drilling to the correct size.

Don
Williamsburg, VA

 

Decided to drill out the Idle Fuel Restrictors and install brass set screw plugs. I used 6-32 X 1/8 inch plugs. Suspect that the shorter the plug, the less restriction on fuel passing through the orifice. I tapped a hole in a piece of steel to hold the brass plugs for drilling.

These are drilled at .032. Well centered in the plugs

Don