I turned my big block into a Prius

[i82much]

Ok not really. But I did buy a 396-powered 72 K10 about three years ago. 3.73 gears and a turbo 350. I was getting around 9-10 mpg on 32's with a 2.5 inch lift, that was country road driving which tends to net you about as good as you are ever going to get in terms of fuel economy.

Anyway, I messed around with it quite a bit and wound up with a new MSD distributor with vacuum advance, Performer 2.0 manifold, functional heat riser, and a quick fuel 680 vac secondary carb, along with a wideband. I dropped the primary side idle feeds one step and got it to run at light throttle at about 14-15: 1 AFR.

Are you guys ready for this? Are you sitting down? Your jaw is about to hit the floor because I got ... 11.5 miles per gallon out of this baby! I know, I know, amazing, right? Especially when the first 1/4 tank or so I still had my hubs locked, although the transfer case was in 2wd.

Ok, not quite a Prius. And I will never make back the money in gas I spent on the wideband, carb, distributor, etc. But, the oil is staying a heck of a lot cleaner, I expect the engine will last a good bit longer, and the plugs should stay clean too. Right now, she isn't a bad daily driver, starts right up in the cold and you can take off, leans out once she warms up.

All in all I am pretty happy with how it turned out. I am thinking optimistically I might see 12.5-13 mpg on a summer day with summer gas and less wind resistance, might bump the tire pressure a smidge too. For a big block 4x4 without any overdrive or fuel injection, I am pleased.