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  #11  
Old 11-05-2017, 10:42 AM
tim2542 tim2542 is offline
 
Join Date: Aug 2009
Location: Redding,Ca
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To reemphasize you must go past TDC to release the impulse coupler, this should happen at TDC, where you will see the TDC mark on the back side of the gear support line up with the case parting line. You will also note the crankshaft turns very easy back and forth 2~3 degrees at this position. Thats close enough for our purpose. Then rotate the prop BACKWARDS to about 40~50 degrees BTDC, then rotate in normal direction of rotation and come up slowly on your timing marks, 20 or 25 as required, indexed at the small hole in the starter as you monitor your buzz box. If you need to adjust, repeat the procedure before checking it again.
You don't need any wooden sticks, piston stops or index wheels to do this unless you feel the need to verify the factory timing marks.
Tim Andres
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  #12  
Old 11-05-2017, 10:52 AM
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JonJay JonJay is offline
 
Join Date: Jan 2007
Location: Battleground
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Quote:
Originally Posted by BillL View Post
Feeling with a probe is OK for getting close (like a couple degrees), but to know with any required precision a piston stop is required. Marks can be off, a piston stop is the only way to be sure.

It does not have to be done each time unless there are no other references (for timing or TDC) when calibrating/setting the spinner hat.
Plus one. I will not time my engines with the timing marks any longer as both of my machines where off. On the IO-360, about a degree. On the 0-320, a bit more than two degrees. This made more difference than I expected in my CHT's.
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  #13  
Old 11-05-2017, 01:06 PM
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blueflyer blueflyer is offline
 
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It helps SO much to have the buzz box attached to the P leads on the mag and not on the ground post.
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