My Pantera is a '71 and I have never liked the throttle cable setup. Actually, the original setup worked fairly well until I broke the cable. The original throttle cable on my car was a simple metal tube that ran the length of my console and through the rear firewall then up to a mounting point near the drivers side of the intake manifold.
I got to thinking that someone must have come up with a better throttle cable than just a piece of twisted wire sliding through a metal tube. I had purchased an aftermarket throttle cable many years ago produced for Hall Pantera and WOW, what a difference! I was impressed with the quality and construction of the new design of cable.
So I installed it in the same stock mounting locations as the original and all was well....for a while.
After many years of performance upgrades including changes in carburetors, intake manifolds, carb leveling plates and such....I began to notice that the throttle cable "feel" was not so good anymore and I had difficulty obtaining full throttle when mashing the loud pedal....which I do a quite often and with much vigor. I would find that when I pushed the gas pedal to it's maximum travel, the butterflys in the base of the carb would many times be only 3/4 open and not fully vertical where they should be when at full throttle. I would also notice that there was a direct correlation between throttle pedal "effort" and how far down I was pushing the pedal. The further I pushed the pedal, the harder it was to push. I always chalked up the increase in pedal pressure to my carb return spring. I figured it was doing a good job.....actually too good!
As I said, this weekend I finally decided to see what I could do about fixing the issue. I recalled seeing a TSB (Technical Service Bulletin) that Ford issued back in the early 1970's about a new throttle cable for the Pantera. I looked it up and saw a photo of where the cable was mounted up near the gas pedal. Wow! My cable was mounted in the stock position which was just a hair off the carpet on the floor but the position in the photo in the TSB was probably 5" higher! Which got me thinking...
If you looked at where the mounting point for the throttle cable near the gas pedal was, my Pantera's cable was pointed at a terrible angle when you viewed how the cable exited and attached to the pedal. Think of it this way, if the mounting point for the cable was at the number 6 on a clock, the mounting point on the gas pedal was at the number 9. This is OK if the mounting point for the cable is pointing TOWARD number 9 instead of barely pointing at number 7 like mine was! I checked the fitting where the cable comes out and heads toward the pedal and found out the cable was actually sawing into the end of the fitting! I was trying to saw my throttle cable in half for years!
To remedy the situation, I raised the cable mounting point from a whisker off the carpet to about 3" off the floor. Then I pivoted the cable mounting bracket so that the throttle cable exited the bracket and was actually pointing at the attachment point for it on the gas pedal. No more sawing by the cable!
I then checked the mounting point of the throttle cable in the engine compartment. This is where things really needed help.
This is where the carburetor geometry comes into play. I had been modifying my engine through the years using the stock throttle mounting point which was just a small bracket bolted to the intake manifold. This was the correct point for a stock carb and stock intake but I was now far from that. I now have a Holley strip dominator intake with a Mighty Demon 750 carb and 1" spacer. This setup has to be at least 12" taller than stock....OK, maybe not that much, but you get the idea.
The problem is that the pivot point for the throttle linkage has changed drastically when compared to the stock mounting point for the throttle cable. Think of it this way...if the pivot point for the throttle linkage is the center of a clock and the location for the throttle linkage at idle is at number 4 on the clock and full throttle is number 8 on the clock, it is nearly impossible to pull the linkage past 6 on the clock if you are trying to pull the linkage from 3" to the left and 3" down of the number 6! From 4 to 6 everything is OK but trying to get to 8 is impossible! That is why I could not get full throttle.
What I needed to do is get my throttle cable mounting point at or above number 9 on the clock so that the cable could be pulled past 6! I hope this description makes sense.
After raising the mounting point of the throttle cable, the throttle response is absolutely phenomenally fast and full throttle is no longer an issue of trying to do the impossible. The pressure needed to push the gas pedal down to the floor has also been HUGELY decreased!
Now someone, somewhere, is saying "Everyone knows that you have to have the mounting point of the throttle cable above the pivot point of the throttle linkage of the carb!" OK, so now I know too.
What difference did this make with my new 540hp 408 stroker? Well, let's put it this way...after 18 years of ownership and 10's of thousands of miles that I have driven my car, I have to learn how to drive it all over again. It has WAY too much power...but I am learning to live with it and will cope the best I can
Hope this might help someone else out there who wasn't good in geometry either.
