I recently bought a Speed Demon 750 vacuum secondary carb to replace my Holley 3310 vac. secondary carb. I was hoping to improve my 1/4 mile performance. The quality of the BG was superior to the Holley so I was rather excited. The excitement went out the window when my 1/4 mile ET slowed by 4 tenths of a second and my mph dropped by 5 miles.The only thing that may be slowing me down, may be the jetting. The Holley used 72 jets up front and none in the back. The Speed Demon uses 76 up front and 83 in the back. Can the jetting be too big for my engine. Is it safe to jett the Speed Demon down to 73 in the front and 80 in the back? I also used the same small yellow secondary vacuum spring in both. Thanks for your help.
Daniel