Poll - How far away from home do you drive your classic?
Last year, I was working on tuning the Quadrajet and, with a #73 primary jet, my best highway fuel economy so far has been 26 mpg with the APT turned out 4 turns from the bottom. I started to get a lean surge at 3.5 turns.
This year, I upgraded to HEI from the Mopar orange box I had been using for decades. This allowed me to turn the APT all the way in (ie, 0 turns from the bottom) without any lean surge. I haven't had a chance to drive it much since then as I've been working to overcome
vapor lock (since the reinstallation of the mechanical fuel pump) and a transmission oil leak.
I'm also using the DC PN P3690788 distributor with 8° initial & 11° centrifugal advance with 7° of vacuum advance for a total of 44° @ crankshaft. For the leaner fuel mixture, I switched to a VC208 advance pod (11° of advance) this summer for total of 52° @ crankshaft. That might be a bit too much advance although I haven't noticed any knock on short drives I've been on so far.
See
Quadrajet Upgrade &
HEI Ignition Upgrade
