Lycoming ring gear position

vbpiper · #1 01-04-2008, 05:03 PM

Sorry about the potentially stupid question, but on a factory Lycoming O-360 A1A, does it matter in what position the ring gear is installed (that is, in what position the t/c and 20/23/25 degree marks are positioned) relative to the crankshaft? Before I mount the prop I want to make sure the ring gear is installed properly. There is a small "0" stamped next to one of the bolt holes.
Thanks.

9Driver · #2 01-04-2008, 05:22 PM

Check the bosses on the crankshaft flange closely. One of them should have a slight shoulder next to the flange. The mount hole on the ring gear with the '0' is slightly larger in diameter than the others. This hole goes on the boss with the shoulder. Hope this helps you.

Ironflight · #3 01-04-2008, 06:32 PM

I had a ring gear on my old Yankee with a 160 HP conversion that had no "indexing" flange on the prop studs - you could put the ring gear on in any position and it worked. I spent a weekend one time after removing and replacing the prop trying to figure out why the engine was so badly timed...turned out the ring gear was on 60 degrees off, and we timed it to the marks on the flywheel. I'd put #1 Cylinder at TDC and then mount the flywheel so that you know it's 0 degree mark is lined up properly - just to make sure!

Paul

vbpiper · #4 01-04-2008, 07:37 PM

Man, I love these forums. I swear I do not know how people built airplanes before the internet (thanks, Al Gore!).

pierre smith · #5 01-05-2008, 05:46 AM

....and A&P mechanics in the 70's. They weren't too crazy about us "EAA-ers". We'd scrounge their takeout altimeters and radios 'cause, as they said, we were cheap. I did, however, build my Cassutt F-1 racer for under $6,000, flying!!

It can be done,

vbpiper · #6 01-05-2008, 01:30 PM

Pierre,
Everyone said that when they move the project to the airport, progress can slow down, but I have found just the opposite to be true. I love leaving the hangar door open and meeting the neighbors, getting folks stopping by to see what I am building, and getting advice from others. I think my wife is happier, too, getting the plane and me out of the house. Never having been a real "airport bum" I am really enjoying it!
There is also an A&P maybe 200 feet from my hangar who works at the airport part time (full time at Boeing) and is a great resource for answering my stupid questions. Of course, when I owned a plane he was the mechanic I used, and will use him for engine stuff (condition inspections and such).
Gotta keep the local guys in business!