Drill Index Sizes #48,49,50 and #52-74


With so many clone carbs out there...especially the 66 center carb you may not know what you have. Say if the carb came off of a 350 the idle idle pick up tubes, could be as small as.029 or smaller. I have seen idle mixture orifices as small as .049.There are many modified motors out there with todays fuels, stroker kits, aftermarket cams and heads. Modifications are necessary to your tri-power to get optimum performance.You can use the various size drills included in the kit to first use as a guide to check what your idle pick up tubes and idle mixtures orifices are. Below I have listed what size drill should be used for various applications.

  • Idle mixture orifices:
  • #50 drill=  .070  STOCK  389 or 400
  • #49 drill=  .073  WILD 389/400, OR 421,428 STOCK TO MILD
  • #48 drill=  .076   WILD 428 UP


  • Idle pickup tubes:
  • #68 drill=  .031
  • #66 drill=  .033 This is for stock application .032 IS STOCK 389
  • #64 drill=  .036 This is for stock application .035 IS STOCK 421 ..ALL FACTORY MOTORS
  • #62 drill=  .038 This is for a STOCK 455 OR A WILD 421/428
  • #60 drill=  .040
  • #58 drill=  .042 

There are two seperate pin vises included in the kit one is for the #52-74 drills and the other is for the #48-50 drills. You can use this pin vise to hold the #48-50 drills  to check what size the ide mixtures orifices are prior to modifications. You will want to use your drill motor with the #48-50 drills as you are going to be drilling into cast iron. CONSIDER PURCHASING THE DVD AS THIS WILL BE A GREAT HELP FOR YOU UNDER THE MODIFICATIONS CHAPTER.......OPENING UP IDLE CIRCUITS/ MODIFYING.

SKU: Drill Index-219


Price: $24.50