Programmable MSD 6AL-2 questions

[68Cuda]

Originally Posted by SSLance

Pretty interesting and educating trip to work this morning. I was mainly looking at vacuum and AFRs at cruise speeds.

In 5th gear at around 2200 RPM (70ish MPH) the engine was extremely happy. Pulling 20-22" of vacuum, barely touching the throttle, would pull any hill with no effort...and AFRs at around 15.7:1 and steady.

I didn't have the laptop hooked to the Ignition box so I don't know what the timing was or what the MAP sensor said the vacuum was...but with no Boost Retard Curve installed, it was just Advance Retard working which would have put the timing advance at around 20* advanced.

In 6th gear at around 1700 RPM (70ish MPH) the engine was not happy. Vacuum was bouncing between 10-15", way more throttle input to keep it moving, lugged down on hills...and AFRs got fat, down to mid 12s to 14:1. Timing would have been around 15* advanced.

Engine certainly needs vacuum advance if I want to use 6th gear on the highway.

Sounds like you are starting to get the hang of it and also getting a better feel for things... once you dive in and start tweaking will be the fun part. Testing and observation is where you will learn the most, then you can come back here and tell us how it is done!