As some of you may know, I’ve been rebuilding the top end of the 410 in our 66 Mercury Monterey. The car runs absolutely great! It idles fine and I can drive all around with no issues. The problem is, there’s like no difference between ¼ throttle and full throttle. The car used to break the tires loose through the first 3 gears and now I can’t even break them loose in 1st on a loose gravel road. My first suspicion is maybe the secondaries aren’t opening? I don’t know. I didn’t touch anything on the carb when I did the rebuild, simply unbolted it and bolted it back on. The carb is (I believe) an Autolite 4100, whatever was factory. I highly doubt vacuum leak because it idles great. I’m just kinda scratchin my head at this point. Ideas?