[Tom Vaught]

More Pictures:

Picture #16 You can see how little Primary Shaft Travel there is before the Cam Slot touches the Roller.
As was Posted earlier in the Paul Bevins article, you can grind away the slot hump so that the roller does not contact the cam until about 1/2 way up the slot, the Secondaries will still open completely with the delayed secondary opening.

Picture #17 This picture is again the Primary Metering Block mounting surface on the Carb Main Body.
On New Carbs this will be flat and have a Dichromate finish that protects the Zinc material that the carb components are made of:
MainBody, Metering Blocks, and Fuel Bowls. If we were talking about other carbs the parts might be partially made out of aluminum.
In this #4224 carb case only the Throttle Blade Base is made from Aluminum.

Picture #18 This is a picture of the Primary Metering Block.
It has the typical TWO Drilled Emulsion Holes on each Primary Carb Bore Circuit, which has worked very well for performance carbs for many years. It has the two Kill Bleed Holes located in the TOP POSITION of the Main Channel of the Metering Block.
It has a Cast In (Non Drilled or Machined Power Valve Metering Block.
The Square Head Plug sealing off the Spark Port Channel is obvious but also the top of that channel has been drilled so that if a person wanted to use Spark Port vs manifold Vacuum to control the Distributor Vacuum Advance it would be possible.

Picture #19 Shows the Number "12" Metering Plate which has a .031" Idle Feed Restriction drilling and a .076" Secondary Main Metering Restriction drilling. A Holley .076" Orifice is roughly the same as a #71 Main Metering Jet.
If you converted the carbs to a cross mount position (like on a Tunnel Ram intake and used a Replacement Rear Metering Block Kit (Part Number 34-6) you would get the Metering Block, longer Bowl Screws, a longer Secondary Fuel Feed Tube, two 'o-rings" and the metering Block gaskets. NOW you could install your #71 Metering Jets in the Rear Position.

Picture #20 is a simple intermediate sealing plate that goes between the Carb Main Body gasket and the gasket that seals the plate to the Rear #12 Metering Plate casting.

Tom V.