Wow, big variences........my old 289 with 3.00 gears used to get 17 hwy with headers int and 4bbl, I built a 330 hp 351w with holley tbi fuel injection and I got 19-20 hwy in the same car and it was WAY faster. Years ago I had a 68 302 4 spd with headers and 500 cfm carter carb and my best was 22 mpg's with a 2.79 rear hwy.

 

289 nicely built, C4, 2.79 with posi rear - started out at about 8 MPG with stock Edelbrock Performer, performer intake and comp cams cam.. Changed rods about FIVE steps, and still a bit rich, but making MORE power and now getting around 17 on the highway. Total advance also plays a part - anything more than 37 degrees is wasting gas... so watch the vacuum cannister setting!

 

Wow I a little shocked by the single digits for the 289. On my 289 I'm getting between low and mid 20's, I think I actually managed 25mpg one day. Then again it is a fresh rebuild, only about 1k miles, a 2bbl carb, 3 speed manual, and 2.79 rear gears. The car is basically stock.

 

I love your avatar remicks! A few of my friends and I have our own little The Office cult I can't wait until the new episodes start in April.

sorry for being off topic