The flow at idle on these carbs is so delicate, that you balance that flow with this device.
You sit it on top of the velocity stack, then equalize the calibration with them with the ball that floats in the glass tube.
Weber carbs have soft brass throttle shafts. Ham handed throttle construction can very often twist them.
Once they are twisted you will have un-equal flows from one throttle plate to another in the same carb. That makes it impossible to sync the carbs.
This sync device will help you determine that.
Weber linkage has to be VERY light basically relying on the throttle return springs built into the carbs themselves.
Many linkage set ups that I have seen require too many additional return springs to zero the linkage.
The return springs go on the center linkage pivot, not the carb throttle levers.
The Pantera linkage is unique to the car itself. Generally speaking you HAVE to use the center tower to make it work.
The side loading linkage that Inglese has are really for the Mustang. It is not going to work properly in a Pantera and likely will result in you twisting up the carb throttle shafts.
Believe or disbelieve but I'm the one who did the initial jetting setup on the Clevelands for Jim, with his parts, but it was me. Circa 1978.
This was all proprietary information then and no one was sharing jetting info on the carbs for this set up. You had to figure it out for yourself.
At the time, the set up was in my 68GT350 and had to use his design for the side loading linkage. Carbs had to be parallel rather then opposed as in the Pantera manifold design.
When it, mine, was transposed to my Pantera, all it would do is jamb open and not return to zero. That linkage design became useless.
The original Pantera Weber design was done by Holman-Moody for Ford and GIVEN to Detomaso.
The center tower is there for a reason. Yon NEED to use it.
Change the throttle design at your own peril. It's your car and you of course can do anything that you want to but it isn't easy being completely on your own. Because of the location of the engine the access to the set up is difficult. You don't want to endlessly be messing with it.
All I can say is that it was my observation that Jim couldn't make it work and went to the side loading.
The only Pantera that I ever personally seen him set up was Andy Carr's back in 1980 or so. He was having problems with the linkage on that car.
I know because I was riding as a passenger in it when he locked up the throttle and spun it on an entrance ramp to RT95 in CT. It was right after a snow storm and there were snow banks along the roadside.
There was no rear deck lid on the car with open stacks, no screens. No Weber cam. Carbs fuming atomized fuel like a volcano.
First time I ever heard the valves float on a Cleveland. That was fun. Yikes!
Glad it wasn't my car.
You have three choices now. 1) work it out yourself 2) pay someone to fix this for you 3) take my info for free.
I'm not an unlicensed MD. I don't right prescriptions. I share my experiences with others. This is not "theory". You can take it for what it's worth or ignore it completely.
"Frankly Scarlett, I don't give a dam", so to speak?
I did my center linkage like this. The benefit is that it doesn't pull on the carbs themselves, just is the secondary return spring tracks require.
The throttle pedal is very light. Feels more like an electronic throttle.
I hope it helps.