There are manual choke conversion kits that include a plastic cap with a lever that replaces the black cap with the wires in your photos. The trick to these kits is to make sure the caps that included are of the same diameter as the cap they are replacing. Sometimes they are not, and the fit will be loose, causing the cap to eventually fall off. Be aware that there is a vacuum port on the electric choke models that must be plugged when converting to manual choke. (Going the other way, from manual choke to electric choke, Edelbrock says this is not possible because of the lack of the vacuum port on the manual choke models.) The proper way to seal up port openings that won't accept a nipple is to jam a small lead ball into them. This allows the ball to be removed with a drill bit and a screw. Epoxy is "forever".
Aside from the idle screws, there are other mixture adjustments on the Edelbrock. On the right and left side of the air cleaner threaded rod, there are two little sheetmetal covers held on by screws. Under these are metering rods. These metering rods, and the jet they insert into, can be changed to alter the cruise mixture. You have to be very careful when changing rids not to allow a screw to fall into the intake manifold. But you don't have to take the carb apart to do minor mixture changes, unlike a Holley. Edelbrock sells kits with extra rods and jets for tuning.
I asked the Edelbrock rep whether there were differences between the manual and electric choke versions of their carbs. He confirmed what I suspected. The manual choke carbs are set up for more power, while the electric choke models are set up for more fuel economy. (Their website now clearly lists the jet and rod size - it didn't at the time I inquired.) The difference is subtle, but the metering rod tables bear this out. What this means is if you are looking for economy, you're better off getting the electric choke model. Otherwise you'd have to get the rod and jet tuning kit for the manual choke model. If you have a "built" engine, the electric choke model may be on the lean side for a healthy cam, headers, etc. You might want to "fatten" up the mixture a bit by installing rods and jets for a bit more fuel.
And note that, unlike a Holley, the rods and jets on the Edelbrock are more than just a simple flow orifice. Because the rods are tapered, they control fuel flow at various throttle positions, depending on how far off of their normal idle position they are lifted. At idle, the rods cut down on fuel flow because they are larger in diameter. As they lift, they taper, increasing the area for fuel to flow. There is a chart with the tuning kit that shows this. It is possible to have more than one combination of jets and rods that will flow a certain amount of fuel at WOT (Wide Open Throttle), allowing you to pick a set that will flow more or less at off idle and cruise. These carbs are much more tunable than a Holley, but they are much less understood than a Holley, and seem baffling to most people. They are often maligned for not being economical to run, but, the people maligning them overwhelmingly run them out of the box and never attempt to tune them by replacing the rods and jets.
The other adjustment is the accelerator pump setting. That's the long curved lever on the driver's front side of the carb. There are three hole positions to chose from.
The Thunderer version of this carb has an adjustable air door. The air door is the movable plate above the secondary butterflies. Your carb's air door is not adjustable, and this sometimes leads to criticism of "bogging" when the throttle gets suddenly opened all the way. The accelerator pump is quite a bit different than on a Holley, and is not as tunable as a Holley, so it is not possible to compensate for the air door opening by providing more accelerator pump fuel shot, other than within the parameters of the three holes on the pump arm, though three different squirters are made (but these aren't nearly as wide a range as the Holleys). It is possible to make the counterweights on the fuel door heavier by adding lead weight to them, but this is something best left to racers. If the problem is such that the weights must be altered, it's best to sell the carb and buy the Thunderer version.
One other bit of advice on the Edelbrock - don't overestimate the size you need for your engine. A common myth is that the carb size is "forgiving" because of the secondary air door not allowing unneeded air flow. This is not quite true, and can lead to bogging. Even without the air door issue, too large a carb leads to less lower end response and driveability. Edelbrock has specific recommendations on their website for engine size and power for what carb CFM should be run, and their advice should be heeded without specific instructions from an engine builder.
Edelbrock.com - Carburetors & Accessories - Calibration Kits
I'm of the opinion that the Edelbrock carb is capable of delivering better power with better fuel economy than a Holley. The problem with Holley carbs is that they are gas pigs. And they run miserably when you try to lean them out. The Holley Truck Avenger is one of the worst carbs to try to run with economy in mind. While it is a great off road carb, able to take severe angles just as advertised, and it makes great power, it gets two to four mpg less than other carbs.
I've dug out my old Edelbrock 750, and am going to put it on the 454 in my pickup in place of the Holley Truck Avenger. The Holley makes power, but 6 mpg is a bit hard on the wallet.
