Well, now I have a couple options to test. My MSD Digital 6 Plus ignition has a step retard that’s activated by 12 volts so I wired a switch and now I can turn it on and off. When on it doesn’t retard until the rpm’s go well above idle so idle quality isn’t affected. I also built a mechanical stop that mounts to the carb base and stops the secondary shaft from opening all the way. I can install and remove it quickly without removing the air pan. I’m going to make a few passes and see how much it takes. If there’s too much stress on the cable I’ll add support under the pedal too. I have a spare throttle cable in case I’m way off on what “stressed” means...