View Full Version : 71 deville w/ 472

11-15-12, 11:55 AM
hello all. i am lucky enough to own a pretty great 71 deville with the original 472 engine in it. great motor, runs well and sounds awesome, only problem is one i'm sure most of you can sympathize with.....gas millage. i'm getting 4 mpg in the city, 10-11 mpg hwy. not very practical for a daily driver, which i would love this car to be. i'm looking for recommendations on what a good replacement motor might be, something more modern, maybe fuel injected, that might get me 11-15 mpg city 20-25 mpg hwy. any suggestions? in the past folks have recommended ls1, but they seem a bit pricey. i myself have wondered if a 4.9 might work, as i have enjoyed the performance of those in the past. any thoughts?

11-16-12, 06:36 PM
I would spend the money on an overdrive transmission long before an engine swap. The transmission in your car is direct drive in high gear and the torque converter is always slipping. Using a 700r4 will provide you with 4th gear overdrive and a locking torque converter. Minor linkage and driveline mods are required and no computer need be used.

11-16-12, 07:06 PM
really? what kind of improvement in gas mileage could i expect from that?


as i side note, i've heard talk about swapping drivetrains, for example from a 93 fleetwood to a 68. the head gasket on my 92 fleetwood just went, so i kinda have one to spare, but is this something anybody of reasonable mind would consider or is it just crazy talk?

11-16-12, 07:20 PM
Crazy talk for the average person. Would you be doing this work or are you hiring someone? Mileage improvement? maybe 20%.

11-16-12, 07:31 PM
definitely hiring someone. i know my limitations lol