Well
If i rebuild my engine what could i do and whats the most horsepower i could get while still keeping my gas milage around 17-18

 

a lot, and a lot

 

Why are you rebuilding it? Alot of mods that you do can actually improve your gas mileage. Like exhaust mods let your car breath easier and get better mileage but nothing major, And as far as the most horsepower, well, the sky is the limit

 

I want my 305 TBI v8 to have 300 at he rear wheels
good rumble to it
and still keep 17-18 gas

is this possible?
how close can i get..?

 

yes, and pretty

 

300 hp is certainly feasable. See the stickies at the top of the board for starters if youve just started with your tbi project. Next you should search the boards here at TGO as well as do some research on manufacturers and see what products you might like to run. If your considering rebuilding oyur 305 it would be wise to consider getting a 350 core to use instead. Also be careful how tight of an LSA you run with your cam. All other things held constant, the tighter it is and the more overlap you have, the more difficult it will be to tune your setup. Id say generally 112 is good but more LSA may be advisable if the cam has some duration.

As for combos, the possibilites are almost endless... So much so that they could never be covered in one thread alone.

Most of what you need to know for starters has been covered on the tbi board as well as other boards here at TGO such as teh tech/general engine and DIY-Prom board. Use the search button, its your friend