I just put a new throttle shaft in my Holley 1850 so I could hook up a downshift rod. Took the '70 Mustang fastback 351w C4 out for a run yesterday and mashed the peddle (while in drive) at about 40mph and nothing! It never kicked down. I've got the kick down adjusting screw on the carb where I think it needs to be. Moving the linkage to full throttle by hand, the kickdown stop arm hits the head of the screw. At this point I'm still able to push down on the rod itself another half inch or so but cannot make the throttle mash the down shift rod that half inch more. The throttle is wide open and won't move the kick down rod any further. Any suggestions?

Thanks...dave