Question for Paul McBride, the General Aviation News engines expert: Hi Paul, I’ve read several of your columns on how to tell the difference between a wide deck and a narrow deck engine.
I was wondering if can you fuel inject a narrow deck by converting an O-320-B3B to an IO-320-B3B?
Bob Johnson
Paul’s Answer: Basically, the answer is yes.
Fuel injection systems have been used on both narrow and wide deck configurations.
However, converting an O-320-B3B to fuel injection may be a bigger mountain to climb than you’re up for.
There has never been, to my knowledge, an O-320-B3B converted to a fuel injected configuration. I’m not saying it couldn’t be done, but it would require a tremendous amount of research.
The actual fuel injection system wouldn’t be a problem, but deciding which oil sump and induction system would be the difficult part.
Several of the O-320 series engines use different oil sump configurations depending which carburetor is used for a particular airframe application and I honestly have no idea which sump would be the correct one for making the conversion you’re asking about.
Needless to say, it would not fall under a certified engine category.
Bob, I’m sorry if I ruined your good idea, but I truly believe it would be an overwhelming challenge to make this conversion to a fuel injected engine.
In over 5 decades of flying, I’ve flown both carb and FI engines. While carb ice is a legitimate issue, it’s not an impossible issue by any means. And FI engines can be subject to disabling induction icing—been there, in a Mooney 231 which had a manual alternate air door, which definitely raised my anxiety level for a few minutes before I remembered to pull the alternate air door’s knob. Both types can be difficult to start when cold—I honestly can’t say one or the other is more difficult. Both types can be difficult to restart when hot, although FI engines are generally much more difficult.
My point is that it’s not worth the expense to convert a carb engine to FI. It may be worth installing a FI engine instead of a carb engine at the time an engine is replaced, but converting isn’t worth it.
To follow up on Henry’s comment.
If the engine is in an experimental aircraft, you can do whatever you want with the engine.
Lycoming does not show an IO-320-B3B model, so you’re on your own.
Why try to convert the engine ? Carbs work ok vs FI, except for the ‘carb ice’ possibility, trading that for the ‘FI ‘hot start’ problem.
Also, if you did a conversion, and if you aren’t a rated A&P, and/or if the converted engine doesn’t match Lycoming drawinds exactly, you’ll have a non-type ceritified engine that can’t be used in type certified aircraft, plus the value of that engine would be in the basement!