I have a completely stock, original 77 L-48 4 speed with 82K miles. When I got it, it ran OK but not great. I richened the Q-Jet idle air mixture screws to 2-1/4 turns out from lightly seated and advanced the distributor just shy of spark knock and slow engine cranking at start up (using premium gas). I made small adjustments from the as-is positions each time and ran the car on a test drive for at least 30 minutes over a familiar route before making the next adjustment to be sure I was actually making improvements before re-adjusting. What an incredible difference in how it runs now! I lost a bad bogging at sudden wide open throttle and the engine runs better at all rev ranges. It feels much torquier and smoother. In the past, I have spent quite a bit of time and money installing bolt-on parts on other cars that didn't produce a more dramatic improvement. It made such a difference that I decided to put my time and money into other more practical "daily driver" type things before I come back to increase engine performance. For just a little time and no money spent, some of you may get a great improvement like I did.