REFLECTOR: Lycoming IO 360 Timing

Scott Derrick scott at tnstaafl.net
Thu Aug 26 11:56:49 CDT 2004


Of course if you use the LSE flywheel/magnetic trigger option you are 
always right on, unless you strip your cam shaft gear.  This also 
eliminates "ALL" moving parts from the EI, a very good thing.

Scott

At 09:58 PM 8/25/2004, you wrote:
><...But I'm sure with Jeff's method of the pin in the case face to the 
>gear you will be just fine for your timing ...>
>Can I be forgiven if I'm not convinced?  I remember back in another life 
>when I was in the auto repair business, we replaced distributors that way 
>- set the crankshaft where we wanted the timing, installed the 
>distributor, rotated it until the points opened (determined electrically) 
>and clamped it down.  THEN we timed it with a timing light.  Typical 
>error: a degree or two one way or the other deg one way or the 
>other.  Setting the initial timing by visually watching the points open 
>generally resulted in 2-4 or 5 deg error.  THAT would be the equivalent of 
>using a pin to position the shaft.  It's not good enough for me.  E-Mag 
>lights a light for you when the firing signal is generated and slick mags 
>will give you an electrical indication (if you invest in a buzz box).  I'm 
>going with E-Mag for a variety of reasons (not least that Jeff Rose is out 
>of business).  I aim to do my initial timing with a timing light one way 
>or another.
>Inability to accurately set initial timing is 3 or 4 points of defeating 
>the purpose of EI.
>
>I am determined to do better than functionally check the chip and time 
>with a nail .... Jim S.
>
>
>Dave Dent wrote:
>
>>You are right to a point.  But you must take into consideration gear lash
>>and pin looseness.  I am sure that with just the rivet on TDC  you would get
>>close enough for anything that would not cause any trouble to the engine.
>>These engines are very loose in the tolerances that it wouldn't make much
>>difference plus or minus one degree plus or two degrees minus.  But two
>>degrees plus could cause problems.  Like I said, "I was running 10:1
>>compression".  That is why I checked it with the meter.  But I'm sure with
>>Jeff's method of the pin in the case face to the gear you will be just fine
>>for your timing.  Some people just want it to the Nat's eye.
>>Dave
>>----- Original Message ----- From: "Jim Sower" <canarder at frontiernet.net>
>>To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
>>Sent: Wednesday, August 25, 2004 5:15 AM
>>Subject: Re: REFLECTOR: Lycoming IO 360 Timing
>>
>>
>>
>>
>>>Doesn't all this presuppose that the unit is installed (clamped to the
>>>accessory case) exactly where it is supposed to be?  Sounds like you're
>>>describing a test of the internal timing logic, but NOT the position /
>>>adjustment of the unit on the engine.  Like, if you loosen the hold down
>>>bolts and rotate the unit a couple of degrees, will that be indicated on
>>>the volt meter?
>>>
>>>What am I missing here? .... Jim S.
>>>
>
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