You didn’t say whether you are looking for a mechanical throttle stop, or some kind of automated air/electric throttle stop. You also didn’t specify the vehicle.
I bracket raced my Mustang for years, usually in classes that only allowed mechanical throttle stops, no “gizmos”. I ran it with a single 4V and mechanical throttle stop, but a few years ago I put the original 2-4V medium riser intake back on and wanted to fabricate a mechanical throttle stop. This is to ET limit the car for different bracket & index classes. What I came up with should work on a Tunnelwedge intake too. I used an old Moroso aluminum under carb plate that I had laying around, it’s the same they supplied with their throttle stop & throttle cable kits. A person could duplicate it. This plate goes under the front carb. I used a thin phenolic spacer under the rear carb to raise it the same amount. I had to notch a corner out of it for clearance, and then drilled & tapped for a carriage bolt for a “stop”. It has a nut to lock it in place. This is on the drivers side of the carb, and the top arm of the factory medium riser throttle linkage cross shaft contacts the stop bolt. A couple pictures below, second picture shows the how the throttle linkage cross shaft contacts the bolt.
I’ll add, one of the nicest mechanical throttle stops I’ve seen on a Mustang was a fabricated contoured thick block of aluminum that was bolted to the firewall, and had a large bolt that was threaded into the aluminum block and adjustable. This block & bolt goes right behind and in line with where the throttle pedal rod on the engine compartment is. The top tip of the throttle pedal rod contacts the bolt head. The Mustang firewall curves considerably at that point, which is why the aluminum block needs to be contoured. This is on a local Super Stock Mustang. I keep meaning to get a picture one of these race seasons. That’s probably the slickest set-up.
