i got here a 90 formula im intrested in buying the owner said he had the 305 swapped out it was from the factory a tpi 5.0 but he says it now has a 350 in it it has an exhaust job headers and mufflers car mostly needs interior work is there a way to tell that its a 350 running with 305 injectors ? will it run poorly , black smoke ? , rough / poor idle , bad gas mileage, service engine soon or even back fire? cuz 5.0 got the 19lb ones and 5.7 got 22lbs will this just effect performance but wont hurt driveability also will it run on a 305 ecm properly? is there injector numbers i can get?

also can i use a corvette ecm in place of the L98 ecm? i heard u can get a few more ponies doing that...?

 

The ecm, if it is a L98, could be for a vette (y body) or a camaro/fire bird (F body).

The memcal (programing chip) will match the engine/car. There will be few, if any, HP gains from swapping. The biggest differences were the heads, cams, and general body layout. The memcal has to match the engine and car for best performance.

The farther you get from a stock setup the more important the tune becomes.

You can make a lot of improvement by programing your own chip.

 

how will the car run if its a 350 with 305 parts? thats my concern

 

It will run but just not at it's best. 305 parts on a 350 will limit the 350 to what the 305 can run. Or something in between.

 

but would it effect mileage or anything of the nature?

 

With an adjustable fuel pressure regulator, running a little more fuel pressure, no difference that you will be able to tell. Only at the higher rpms will the 19 # injector be too small (run static).

Most of what you described is caused by a stock chip/engine, a lopey cam (too big) and too larger injectors.