26th Oct 2013, 18:35
To 15th Oct 2013, 23:02 from 4th Sep 2013, 15:10
To get better mileage from the 455, try advancing the spark timing & use the highest octane gas you can get. I once had a 1972 442 with a 455 that gained approx. 2 MPG by doing that.
In my experience, that's about all you can do to improve a 455's gas mileage. Keep in mind the fact that the last thing that the 455's designers intended it to do was to get good gas mileage.
21st Oct 2013, 11:57
I'm sorry to say, but 10-12 MPG is about the best you'll ever be able to get with the Olds 455. There's really no way around it, except for buying a smaller, more efficient car.