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
- ON MODIFIED CARS, START LOW AND WORK UP. CAN'T GO BACK!
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.