Need advice for diff for 65 Dart factory hi-po 273.

gtxdude said
I don't get it. I'm running 8:25 with 3:21 gears. Pulled off my rpm air-gap and put performer intake on earlier this summer with AVS-2 650 edelbrock. Mild 318 250hp 904 tranny. 25" tires in back. Anyway, was getting between 12-13mpg maybe 13.5 on hwy. After switching intakes maybe picked up 1/2 mpg. We do alot of cruising and would love to improve mpg somehow. I keep thinking since changing intakes I could get by with a 500 eddy. Anyway, saw your post and thought "how does he do that?"

9.6/1 HP 273 with the stock open plenum intake and a 600 Edelbrock. It has a Isky E4 cam still running the solid lifters. I also run the original dual point distributor with 8 ° initial and 32° total. Stock exhaust manifolds with Accurate LTD Hi-po single exhaust. I get 18+ easy and have gotten 19 on a 2 hour drive @55 mph. Oh, original 4 speed. (non overdrive)