428 vs 390

[snake]

Any thoughts (or better yet, experiences) with fuel mileage between a 390 and a 428?? (all else being equal of course)

I have both and both need complete rebuild. Obviously the 428 will give me more HP but at what cost regarding fuel mileage???

[mrtleavitt]

Not enough difference to keep you from going with the 428. My bro runs a 390 and I run a 428. Both get 7-12 mpg depending on how we drive them.

[ximy]

wow.. I've built 390's and 428's but never considered mileage... ... the 390 makes more than enough power for any standard use... the 428 will blow your socks off with torque... give it mild upgrades.. manifold, carb, cam, header... and Holy Smokes!!!

[snake]

I don't know that I'm really 'concerned' about the mileage since it will not be a 'daily drive' but if I ever get the truck back on the road, I will use it for hauling things and at some point I will use it to pull a trailer occasionally(vintage stock car).

Again, I say all things being equal since any rebuild components and services as well as upgrades (intake, headers etc) are essentially identical and have the same costs...

I was kinda thinking that it only makes sense to do the 428 but wanted to get some input in case there is a drastic difference in mileage. As stated above, I'm sure the 390 will do just fine for what I want but since I have the 428 too, why not???

Thanks for the input and any additional comments are also appreciated.

[ximy]

build a stock or mild 428 then.. it can pull planets out of their orbits

[brandon.k]

In the mid to late 70's my uncle had my pickup and used it as part time street racer and full time farm truck. It had a 428 with some really wild CompCams cam shaft in it, 780 Holley, Headmen headers and not sure what all else. It was fast and a for sure work horse but im not sure on the mpg..