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.