1979 deville

[trife86]

hey guys. theres a 79 deville for sale near me and i know it has a 425ci engine but what kind of power does this thing make and what is the average mpg can i expect from it?
any info would help

[davesdeville]

I get about 9mpg city (lead foot) with my 425 in a slightly heavier car. It's really not too fast, but it's a good candidate if you want to build up a 500/472 and still have a running car.

[trife86]

hehe well what kinda of power is it rated at? it would be my 2nd car to get going my 90 towncar has seen better days

[Angela Desmond]

Allante North and I are both doing 425 project engines at this time. With the parts I'm using and my modifications, "Desktop Dyno" projects about 440HP and 480 ft.lbs. of torque. If I'm not mistaken they were originally rated at about 150 net HP. My husband used to get about 14mpg on the highway commuting to work. There's plenty that can be done to them, but for really monster torque, it's hard to beat the 500CI. If you're going to build it up, you've come to the right forum. You should be able to avoid any of the pitfalls we've discovered in our attemps at power.

[caddydaddy]

The 4 barrell 425 made 180 HP at 4,000 RPM and 320 lbs-ft of torque at 2,000 RPM's.

[78425sedvil]

Originally Posted by trife86

hey guys. theres a 79 deville for sale near me and i know it has a 425ci engine but what kind of power does this thing make and what is the average mpg can i expect from it?
any info would help

mine is stock with a tired motor with 2 cylinders constantly fouled and it puts out 180 hp at 4000 and 380 lbs at 2500