A1A Crank in an A4A Engine?

Hello,
I know this isn't an RV related question, but I know that this forum has alot of Lycoming knowledge floating around, and it is very active so I thought I would ask you guys this question.

I just bought an Acrosport II that came with a disassembled O-360 A4A. The engine is almost complete, but it is missing the crank. I found a nice yellow tagged O-360 A1A crank, but I am not quite sure if it will fit or not. I read the type certificate for the O-360 and the only differences between the two engines are that the A1A is equipped for a constant speed prop (hollow crank), and the A4A is not, and the A4A has special length propeller bushings. I am going to be using a fixed pitch prop, but I may upgrade to a constant speed prop later. Can I use a plugged, A1A crank, in an A4A engine? Are the cases identical, or is the oil routed differently? I don't suppose there is a downloadable Lycoming parts manual on the internet anywhere is there?

Cameron

The A4A case has a hole drilled in the nose bearing boss webs, to vent oil pressure and promote oil flow through the nose bearing. So an A4A case will not work for constant speed unless you plug those holes. Other then that difference, the cases should be the same. If you have a solid nose crank, you need a vented nose bearing bore and if you have a hollow crank you don't, other then that, the shafts will fit either case. If using the hollow shaft for fixed pitch you need to vent the oil pressure that can build up in the nose bore of the hollow shaft by putting a hole in the rear nose bore crankshaft plug or removing that plug. Or you could use a governor drive plate that will vent that oil pressure back to the sump, if you are going to install the governor drive and constant speed plumbing.
Good Luck,
Mahlon
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