Better than expected gas mileage

[mikep]

I took a little road trip of nearly 300 miles today to meet up with another board member to do the old cash for parts thing and I was suprised by how good the gas mileage was and I got an added bonus. Now the specs are as listed below but to sum it up its a 350 with an rpm intake, 750 holley , hei and a solid lifter compcams XS 274S cam using 1.6 rockers and 9.5:1 compression and 36 degrees mechanical timing and an additional 12 degrees vacuum and 3.54 gears in a 4500 lb 3/4 ton. This is the first time out on the hiway with the new cam , intake, carb and automatic transmission with 2200 stall converter.

Before I changed all the above in the last month I was getting a pretty consistant 13.2 mpg on the hiway with a performer eps intake, 600 holley , and performer cam and there wasnt anyway in hell that thing would run on less than 92 octane gas. Now I am getting a surprising 12.4 mpg and the kicker is the extra overlap of the hotter cam is letting me run it on 87 octane without detonation. To be honest I was stunned . I wasnt expecting the added fuel efficiency. Sure the mileage went down by 1 mpg which is a good 8 percent or so but it gained a good 40-50 hp in the process and with the cheaper regular unleaded gas its probably actually cheaper to run now. Of course this is all about to change as I'll be going to a bigger set of heads this year and 4.88 or 5.13 gearing . Its no longer my daily ride so its time to have fun.