Join Date: Mar 2002
Location: San Francisco, CA 94114
I'm trying to get my 302 dialed in and I figured some of you guys have way more experience than me. Here's what I've got...
780 DZ carb
6.5 primary power valve
8.5 secondary power valve
idle mixture at 3/4 turn
yellow secondary spring
.025 pump shooter
lowest observed idle vacuum of 7 inches
accelerator pump arm and floats properly set
nice lopey idle at 950 rpm
With this setup, the car has a rich smelling idle, a slight hesitation when going to full throttle and a chassis dyno air/fuel ratio of 11.5:1 at 4,000 rpm and 12:1 at 6,000 rpm. The plugs also read rich.
The first change I made was jetting down the carb evenly from 68/76 to 66/74. This gave the car crisper throttle response and a stronger top end charge, but I picked up a slight steady-throttle surge between 2,800 and 3,200 rpm. I'm guessing the surge is a lean condition from the new primary jetting. I richened the idle mixture 1/4 turn and then 1/2 turn, but this did not cure the surge.
As a next step, should I go back to the 68 jet in the primary to cure the surge and change the both power valves to a 4.5?
I really appreciate any thoughts you might have.