What's the best way to clean up this burr, emery cloth and a bit of oil or a hone? I can feel it with my finger nail, could this be cause for a slightly erratic idle?
Which burr?
The ring around where the throttle plates close, near the bottom of the transfer slot.
I dont see that affecting anything unless the butterfly is catching it. You could probably knock it off with a pocket screwdriver.
I can see it affecting the idle as Holley even say to hold the base plate up to a light to ensure the plates are centered as it would affect idle if not centered. I cleaned it up as best I could without going too aggressive on it.
I also tried to order a new throttle shaft as well but apparantly Holley hasn't made the early style shafts for 10 years. I managed to get the teflon strips in the primary side which fixed the worn/wobbly throttle shaft, but I'm not convinced they will last long. Man those things were a bitch to get in. The worn base plate is what allowed the throttle plates to rub the bore causing the "ring"
The other option is a reamer/ bush kit which by that stage a new base plate is likely a cheaper solution.
If it is not catching the butterfly, the idle transfer slot gap is correctly centered, and the engine idle is not too high, it is not a problem.