[Tom Vaught]

It has been a while since I posted in the Holley Carb Tip Thread.

I will post a few pictures today.

Then I will describe what each picture is showing us.

1) In the first picture , the pointer is showing the "Adjustable Emulsion Jets installed in a Special Holley Circle Track Metering Block.

2) Second Picture shows a neat little jet that is actually a "Kill Bleed" for the Accelerator Pump Circuit to keep fuel from being drawn
out of the shooter at high speed and screwing up the air/fuel mixture you worked so hard to get at max power levels.

3) Third Picture pointed is showing the LOW POSITION Idle Feed Restriction (this position works very well for many carbs).

4) Fourth Picture shows the later style High Position Idle Feed Restriction (This position supplies air and fuel to the idle circuit and
many times causes a tuning issue with the carbs. Many Knowing Tuners move the IFR back down to the low position and the
tuning issues go away.

5) Fifth picture shows the Adjustable Power Valve Channel Restrictions. For max power conditions you tune with the PVCRs and not
with the Main Jets. Some do not know how to do this so they just remove the PVCRS, install PVCR "plugs" and try to tune the carbs that way. It might work ok on a 1/4 mile car but on a track car or a street/strip car, using the Power Valves and the PVCRs is the way to go.

Tom V.

ps the older holley carbs did not have these features because of two reasons: "One" the extra machining cost money and "Two"
Holley wanted to sell more carbs vs allowing a tuning capability by the average enthusiast. Today the Enthusiast with a Air/Fuel
meter can get close to what the Holley Engineers used to do with calibration changes. Today you spend a few hundred for the meter and
UEGO sensor, in the old days (60s) Holley would spend thousands for a professional Lamda meter.