[Tom Vaught]

A few more tips for people today, these are related to Holley 2-BBL carbs, specifically the old Tri-Power Carbs used on the 340/440 6-Pack engines and the Tri-Power Carbs used on the Chevrolet 427 Corvette engine.

So in the 1st Picture, we have a Vacuum Tri-Power Set-up 427 Corvette. How can you tell from the picture?
Several ways really:

a) The fuel line connecting the three carbs is on the same side of the carbs as the Primary Carb Throttle Arm.

b) The Sight Plugs (that allow you to check the fuel level in the carb bowl) is on the same side of the carbs as the Primary Carb Throttle Arm.

c) Without even looking on the Passenger side of the engine, the center carb only has the metering block with mixture screws so the carb set-up is a vacuum diaphragm set-up.

d) Another key to the vacuum set-up is the connecting arms on the bottom of the three carb throttle arms. This group of parts make sure the secondary throttle blades close when the Primary Carb blades close.

Picture #2 shows the sight plug mentioned above and the required Washer to seal the plug to the bowl threads.

In the third picture, you can see that the carb we are discussing is one of the "outboard" carbs. WHY? because the airhorn is not drilled for the choke shaft. The center carb would have the choke shaft hole and shaft visible.
But there is another thing happening in the picture. Can you see the "Vapor Fog" above the carb? This tells you that you have a internal leak somewhere in the carb assembly.

In Picture #4, the metering plate is not flat, as shown by the feeler gage measurement.

In Picture #5, The Tuner is adjusting the Mixture Screw on the Drivers side Primary Carb Idle Mixture Screw on the Metering Block.

More on this subject later.

Tom V.