I have a 99 7.4 mpi 310hp, Im close to pulling off the fuel injection and putting on a carb, heres what I had in mind. 750 vacume sec with rpm manifold . can I keep the computer to control the spark I like the idea of keeping the knock sensor and the warning buzzers. I think the fuel injection doesnt send any signal back except for throttle position. Id like to see around a 30 hp improvement at the same time Im going to change my exshaust tips to unbaffled. has anyone done the swap by itself? I know worse gas milage harder starting but hell I can tune a holley and I cant tune the mpi

any ideas?

Leave the Injection on.

30 hp will get you about 1-2 mph .... not worth the hassle

Spend a couple hundred bucks and have your prop blueprinted.

My $.02

does anyone know if you can run the mpi's ecu with a carb?

Leave it alone. It isn't worth the money for what you're trying to achieve. Boating is suppose to be turnkey and that's what you have now. You start messing with an already proven product and you're in for some days of sitting at the dock and scratching your head. I know from experience. DON'T TOUCH IT! Hey, you asked.

In for a penny in for a pound. I have not done what you have in mind. Just read about these type of minor changes. I think the above thoughts are correct. On the other hand if you were to put some decent heads, cam swap and exhaust with your carb you might get somewhere. Now the scope of your project has changed. Once you go that far you may start to consider a 502 crate motor.