DerekTheGreat
Forum Regular
It's the tbi holding you back.
I had a 305tbi w/ 4l60e, 3.08 and got 10mpg if you were easy on it or hard on it.
Swapped in 3.73 (about this time I got another daily so thought what the heck) still got 10mpg.
Strapped on a supercharger and crammed about 7psi into the tired engine, still 10mpg.
Puked the motor and swapped in a stock 305 out of an 86 caprice with 400000 on the clock and instantly got 17mpg with my foot to the rug most of the time.
Though that's without towing a trailer but had a pair of 3 wheelers in the box from time to time and that didn't seem to change the mpg.
I'd assume by swapping to a carb you should be able to get 15mpg unloaded and around 10-12mpg loaded
This is post is laughable. It could be picked apart from so many angles such that all I'm going to say is that you will not get better MPG swapping to a carburetor and that the TBI system isn't holding the vehicle back.