REFLECTOR: Lycoming IO 360 Timing

[Jim Sower]

<...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.
>>    
>>