What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

IO 360 Assembly Question

mandorfer

Active Member
I am assembling my IO 360 and have a question about the Lycoming procedures. My crank was worked by Aircraft Specialties and my case was worked by Divco. The crank was turned down M006 for the main journals and M003 for the rod journals. I mic'd the crank journals and they are right on the numbers for M006 and M003. I bought the correct M003 and M006 Lycoming bearing sets. The Lycoming manual directs you to install the bearings in the case without the crank installed and close up the case to be able to mic the final ID of the bearings and then disassemble the case again. Is this really necessary? I noticed that other IO-360 assembly manuals (Superior XP for example) do not direct this step...it has you move straight to installing the bearings and crank. Thoughts? I understand clearance is important, but coming from a reputable shop like Divco and having brand new bearings it seems overkill. Thanks.
 
I used plastiguage. Worked well. Just be sure you don't move the crank.

If you are building a Lycoming engine I would follow the Lycoming manual.

I had a reputable shop screw up machine work. (Actually the part was fine, they screwed up the paperwork. Found it after the bearings were clamped so no returns. ☹)

DEM
 
Never assume anything when it comes to machined clearances. I've had several "reputable shops" make machining errors over the years. Either get a snap gauge and micrometer or Plastigage.
 
I always use Plastigauge on crank assembly, although I have never assembled a Lycoming.

A good trick is where to buy Plastigage. Try walking into an Auto Zone or O'Reillys and ask for it. You will get an empty look that might as well be a black hole. That's what happened to me the last time I was building an engine.

Of course with the wealth of online resources we have now, not a problem.
 
I always use Plastigauge on crank assembly, although I have never assembled a Lycoming.

A good trick is where to buy Plastigage. Try walking into an Auto Zone or O'Reillys and ask for it. You will get an empty look that might as well be a black hole. That's what happened to me the last time I was building an engine.

Of course with the wealth of online resources we have now, not a problem.

Rockauto.com
 
Thanks

Thanks all. I assembled the case and mic?d the bearing ID?s and all clearances were good. Pressing on to the next challenge!
 
New hardware

Another good question is after you check clearance with case halves assembled, do you now use new nuts since you've now removed cad from the studs, changing torque value.
 
Back
Top