Q: Paul, my Lycoming O-320 B2A s/n L-504-39 looks like it has a hollow crank.
It also has an available accessory pad below the right magneto. And a 1/4″ plug on the right forward case in front of the #1 cylinder.
Am I able to run a constant speed propeller on this engine? It is on an Acrosport II.
Guy Juntunen
A: Guy, from the information you provided, including the photo, I think you’re okay to use a constant speed propeller on this engine.
I’d recommend you review a copy of Lycoming Service Instruction 1435 and its Supplement No. 1. This should provide you with all the necessary technical information you should need to move forward with your project.
To be legal you would need an STC for this, if it’s not listed on the type certificate for your aircraft. Or change the status of your aircraft to experimental.