Well, the 383 Formula is offivially on the road.

Most part throttle tuning is done and I have a couple low end fueling issues to work on as well as finish tweaking out the timing curve.

Its break in run was roughly 400 miles to Bowling Green, KY.

First tank was 20.5 and the second was right at 21mpg. this was cruising with the cruise control on and varying speeds due to the fresh motor, I was doing from 55-80mph.

While I was down there I did some more tuning and logging at nite and in the am and further worked the fueling and timing.

The way home was way windier out and we had the windows all the way down. I managed to get 21.45 mpg.

I expect the mileage to increase slightly as the engine breaks in and the tune is further tweaked. Hoping for 22-23 highway before playing with anymore tricks like hihgway mode in the tune.

later
Jeremy

 

ahhh who says thirdgens aren't made with fuel econmy in mind?
as i said before it's better then driving a mini van or a suv....

 

Last week I made it to Carbonadale on 1 tank. 379 miles with fuel to spare. 31mpg and it is has been running a bit rich ever since I installed a Bosch o2 sensor.

 

Throw away the bosch 02. they have known ground issues. Only run a delco 02 period.

305 TBI cars are known to get very good mileage from the factory they have the highway mode invoked thus leaning fuel out further than normal.

Most people that I have known with the 305 TBI 5 spd are in the upper 20's on the highway.

later
Jeremy

 

I was shocked, I've made that trip many times and the best I've gotten up to now was 28mpg.

 

Is your 383 carb or TPI?

 

TPI w/ cut SLP runners and plenum w/ vortec base.

later
Jeremy