The first step was adding some metal to the existing throttle arm. I searched through the scrap metal box and found one of the tabs I had removed from the four note Buick horn mounts I had installed earlier on The Clam. This piece was the exact same thickness as the metal for the throttle arm so it worked out perfectly.
First I cut out the shape I needed so it would fit flush then I beveled the edge to give the weld good penetration.
I used a grinding disc on the angle grinder to smooth it out.
To remove the arm I would have had to disassemble the carburetor, which I am not equipped, skills wise, to handle, not to mention that the carburetor seems to be functioning, so far, perfectly and I have found that when an old carburetor is working good, do...not...mess with it. This meant that getting to the back of the arm was a bit difficult. I put three tack welds on the rear to give it more strength.
With great time and difficulty I was finally able, I believe, to find the center line of the shaft to determine the perpendicular, 90 degree line as well as the 23 degree line that will serve as a guide, or plane of reference, to drill the TV stud hole. What made this difficult is that the shaft sits above the bottom of the carburetor so that means that the point where the two lines on the paper intersect, which is the center of the shaft, is a point off and above the paper, as well as a point blocked by easy measurement by all of the do-dads attached to the throttle arm shaft and carburetor.
Because the center of the shaft and the mounting surface of the arm were on different planes it was necessary to look straight down and eye the measurement with the caliper. This meant that the carburetor had to be standing perfectly straight and that the line of sight had to be perfectly straight when looking down on the measuring points. This makes it very difficult to get exact measurements. This picture isn't exactly accurate, but it gives an idea of how the measurement was made.
I drilled the hole and then used a grinding disc to shape up the new throttle arm. Then I primer and painted the bare metal.
The threaded shaft for this TV stud is pretty large, about 3 times bigger than the hole that can be seen below it for the return spring. After I was finished, to the best I can tell, the hole is about 0.05" (Five Hundredths of an inch) too close to the center of the throttle shaft. According to the information I found the hole should be located with a tolerance between 1.094-1.125" away from the center of the shaft. Mine ended up being approximately 1.04". I'm going to try to find someone knowledgeable on this topic and see if I need to weld the hole back and redrill it. It could end up that the hole in the arm of this carburetor could cause substantial harm to the rebuilt 700R4.
