Hi all, I'm looking the length of the throttle linkage throw from the throttle lever to the kickdown/switchpitch.switch between full throttle and zero throttle. The length of the throw determines how the switch will operate.
I measured from where the linkage crossed the vacuum line, but use whatever works best for you.
I'd really appreciate the help!!!!!
Dave
1967 442 ragtop

 

I adjusted mine so that WOT travel is set correctly to get WOT at carb without any extra pressure on the throttle linkage. Also make sure throttle goes back to idle cleanly. The switch pitch switch does not need adjustment, just needs to be mounted and connected correctly.

 

I fully understand how the switch works, but I have some nonstandard parts and I'm not getting proper operation of the switch. I just need the measurement that's all. Can you help me with the measurement?
Thanks
Dave

 

I am happy to pull some measurements when I get home this evening. Hopefully someone beats me to it but if not, I will get back to you soon.

 

That would be awesome!!!! I spent 20 years in the DFW area and the biggest thing I miss is the great BBQ and the pretty women, not always in that order.
Dave

 

Hey Dave,

I took a queue from you and used your method to measure. I am getting 1 3/8 in. throw. Let me know if this helps. Thanks, Matt

 

Thanks, Matt.!!!

 

I’m a big car guy, but I’ve been working with these rods for decades. Maybe my thoughts below will help. Here and there with these rods can you get cornered by an carb (upper) rod screw-length setting that idles great, but doesn’t open the carb 100%, or opens the carb 100%, but doesn’t settle back down to idle properly. I’m no mathematician, but this is geometry of angles, start stop points, and so on.

1) If you set the carb throttle rod tight to completely open the carb secondaries, watch out for stress on the now-rare kick down switch if you have an automatic. Make sure that however tight you set the wide open position, that it does not pull forward on the kick down switch. Over time engine movement (forward/back & right/left) can tear the switch off its mount if the rods are set too tight. Ask me how many I went through looking for power in my 20’s (and maybe 30’s)… The trick there is disconnect the rear of the rod from the kickdown switch, then pull the carb all the way, like 100% open, then look at the rearward position of the back of the throttle rod. The position of the ball-void should be _exactly_ at the full open position of the kickdown switch. And not short. If it’s short, you nail the throttle and the engine movement in its mounts puts a forward pull on the kickdown switch. Which can eventually tear the pot metal. If in doubt, leave the throttle rod just 1/8” long so you can keep your switch for a long time. You might give up a few degrees of throttle opening, but you’ll have a working kickdown switch for longer. That brings me to the forward/aft position of the entire throttle assembly relative to the engine. The lower rod controls that distance and angle.

2) Lots of the lower (engine-to-kick down switch) rods are fixed length. Which make sense since GM wanted to control costs. But if you’re resourceful, you can buy an adjustable one. Try hobbyists, here or specialists. Or make and adjustable one using parts from your local hardware store’s Hillman section. I found the adjustable lower rods really allowed me the freedom to dial in the angles and get things set so throttles open completely & switches don’t break.

3) The ends of these rods are 1/4” in diameter. So the hardware the need to get are those spheres and other hardware that fit together well. I sometimes polish mating surfaces with #0000 steel wool to make the roatation super smooth. I like a smooth rotating throttle. So polish, then lubricate mating surfaces with your favorite grease for smooth operation
4) To make things easy I tend to use or drill a 5/16”s hole in my carb primary throttle (the vertical part on the driver’s side) and then bush it with a teflon or rubber bushing (to allow a little “give”, but allow totally smooth throttle rotatation). I’ve tried drilling higher and lower holes to increase or decrease the “gearing”. In the end I wound up right back at the factory-located holes as the best option.

5) Joe P. will tell you that GM abandoned throttle rods after some incidents of them pinning the throttles open. That is clearly a risk here. I believe throttle cables are safer. If you want to be really safe, go with the later solution. My impression from him is that the stuck throttles happened maybe because motor mounts broke and engines “twisted” in the remaining (usually right) mount and the rods just got stuck. Open. Oh sh*t. Cables are safer.

6) Looking the mechanical interference between that vacuum booster vacuum hose and throttle rod, I’d be tempted to reroute the vacuum line beneath the igntion wires, well below anything like interfering with the thing that opens the carb to WOT. That may not be correct for Cutlass/442 though. In that case, I’d angle the routing hole rear/down a few degrees to create space between the vacuum line and throttle rod.

7) Just for looks, that #0000 steel wool works wonders at polishing the rod itself. It tends to remove dirt, grease, grime and so on. Pure aesthetics. Not functional.

I’ve gone on too long. Hope some of this helps you.

Cheers
Chris