Formula 311 Engine Swap
 

Hi Guys,
Had my 1990 Formula 311 over a year now and absolutely love it!!! Unfortunately, it came with the 330's. So I am buying a set of 502 MPI's to wake it up a bit.

I'm assuming they should pretty much drop right in. I'm sure some of you have made this swap. Are there any issues here? I think I read somewhere that there might be an issue with the silent thunder, but I don't se how that could be.

Any thoughts would be greatly appreciated.

Nope, easy drop in. Mine came with 330's swapped to 502 MPI, then I swapped in HP500s. All no sweat. You should get the Merc Manual to hook up the kill switch and a check engine light/buzzer but other than that you are good to go.

Thanks for your response Ted. That's what I thought - just wanted to confirm. What is the difference in performance between a carbureted motor and EFI? I here some people pulling the EFI and putting carbs on the 502's. What would be the reason for this? I've only ever dealt with 330's in my boats so the whole EFI is new to me.

People pull the EFI because they don't understand it. I get that, but it is far superior to carb engines. The problem we see now though is the injectors get sticky or clogged from ethanol in the fuel. I recommend having the injectors flow tested a minimum of every 2 years, every season if you run hard. At 25 bucks an injector it is good insurance. Also if you are going to increase power you have to have someone reprogram the computer, easy enough to do, but some guys are better than others.

What numbers were you running with the MPI's? What props?

About 68 on 26 pitch Bravo 4 blades. Ran it at 71 once or twice, really light and trimmed up with no drive showers on it. The drive showers cost me a couple of MPH.

Fun project, ours turned out great. Everything bolted up very easily.
I went with the carb for easier tuning down the road with the updates I wanted to do.

Thanks guys!

How much would be reasonable to pay for 330's pulled, new engines dynoed and istalled?