REFLECTOR: Lycoming IO 360 Timing

[Dave Dent]

I have ran Jeff Rose systems since 1995 and found them great on a 10:1
compression ratio set at 25 degrees.  But I must worn you, if you time it
after you have adjusted the TDC and then run a timing light on it you  may
have problems.  First you have to have the vacuum plugged to do the test
with a light.  Then it has to be a very high quality timing light.  Most
jump all over the place.  It is very hard to do it with a timing light
hanging over the top of your engine pointing it at the back of your
flywheel.  It can be done but on a Velo, not recommended.
The best way to time a J.R. system is this:  hook a volt meter to the adv.
connector on the computer module.  With the red lead to the tab and the
black from the meter to ground.  Then disconnect the vacuum  line from the
advance box that screws onto the computer main body.  With the vacuum module
removed from the computer you will find two adjustment screws.  One you
don't touch the other is the advance adjustment.  Now start the engine and
it should run if you are any thing close to 25 degrees.  On the volt meter
you should be reading in the volts selected position 25 volts.  If you don't
see 25 degrees move the knob that reads adv. to change the volts to read 25.
It is a very fine adjustment but you can bring it in to be right on.
I had my coils and computer inside the aircraft so I could reach them while
the engine was running.  This may be hard for you if you have them on the
fire wall.  Be prepared to start and stop your engine for the adjustment, if
off.
Now if you have two systems, with a single vacuum hook up (best)  remove the
jumper wire from the primary computer to the second one so they can be seen
independently.  If you hook the VO meter to both adv pins on the computers
you can see the average between the two  units.  Try and not have both units
firing at the very same time.  Have them at least a few tenths of a degree
apart from each other.  If at the same time the engine will have a bigger
bang at the time of firing and won't sound right.  I had mine at eight tenth
of a degree apart.  Ran great.  Most want them one degree apart.  You can
get them that close with this system.
After the adjustment hook up the jumper wire between units and put the
vacuum advance can back in place with the two screws.  Unplug the vacuum
line and hook it back up to the advance can.  You shouldn't  have to check
this again for at least another 100 hours.
Jeff was selling a little volt meter you can install in your panel to get
the readings while you fly.  After my volt meter set up I don't think I used
the panel meter more then a few times and then never looked at it again.
This I found to be panel space needed for something better.
Dave
----- Original Message ----- 
From: "Ronnie Brown" <romott at adelphia.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Monday, August 23, 2004 11:04 AM
Subject: Re: REFLECTOR: Lycoming IO 360 Timing


> Hi Steve,
>
> I have thought about trying that - but I'm afraid of spinning props.
>
> I have had my A&P IA and another A&P check my Slick Mag setting.  They are
> correct by the book.   The Jeff Rose is at zero per his instructions - I
> have the mag hole pick up.  You put a Pop Rivet nail in the setting hole
at
> zero degrees (TDC).
>
> 25 Degrees is what is stamped on my name plate, but I ran across a
Lycoming
> Service Bulletin that says it should be reduced to 22 degrees - but the
> bulletin never said why Lycoming had changed their mind.  After reading
the
> note on CHT's, and detonation, I understand why.
>
> You think I need to reduce it to 22 degrees even though my CHT's are cool?
>
> Ronnie
>
> ----- Original Message ----- 
> From: "steve korney" <s_korney at hotmail.com>
> To: <reflector at tvbf.org>
> Sent: Monday, August 23, 2004 1:26 PM
> Subject: RE: REFLECTOR: Lycoming IO 360 Timing
>
>
> | Ronnie...
> |
> | You need to check your timing with a timing light to verify it's real
> | position...
> |
> |
> |
> | Best... Steve
> |
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