Bart - with absolutely no offense meant, a DYI throttle shaft repair kit will more often than not result in a throttle body that requires MAJOR expense to repair.
You asked about a reamer. The reamer is the LAST step in finishing the job, not the first.
The throttle should be first milled with a centered end mill, and never through to the throttle bore. The mill should stop leaving .025~.035 inch of the original throttle wall to preserve the integrity of the curvature. Once the throttle body has been cut, the bushing can be pressed into place, and the throttle body turned to do the other side. Once both sides have been done, then the reamer comes into play.
If one uses an oversize reamer and reams through the throttle wall into the throttle bore and then inserts the bushing; there will be two small triangles where the square end of the bushing fits against the round throttle bore. While leakage from the outside may be eliminated, these two triangles will cause internal leakage that normally results in a higher than normal idle, as air will bleed past these triangles even with the throttle blade(s) conpletely closed.
Before doing anything, measure your clearance with a dial indicator. Design tolerance at the factory was 0.004~0.006 inch. Some wear is normal. Generally speaking, if the current clearance does not exceed 0.009 inch, it will be fine! When we were rebuilding carbs (we no longer are rebuilding carbs), we found that 0.0055 inch was a good finish.
If the dial indicator shows more than 0.009 inch, then take the throttle body to a local machine shop that has a good vertical mill and do the job right.
And yes, a meticulous hobbyist can do the job with a really good vertical drill press and milling vise; but will never achieve the same results, and the bearings in even a good drill press will have maybe 0.003 inch wobble. Trying to use a hand drill is simply asking for trouble.
If the machine shop has no source for the splined, thin wall bushings, call me.
And if after reading this, you still want to do the job yourself, try MSC Industrial Supply for reamers.
Jon.
