REFLECTOR: CHT too cool
davedent at comcast.net
davedent at comcast.net
Wed Jun 10 00:50:24 CDT 2009
I had two of the Jeff Rose systems on my old Long EZ. I could adjust them both by removing the MAP hook up and run it on the initial set point. You can read it by clipping onto the spade that is labeled adv. It's one that is not normally hooked up unless you have a meter that reads it. I had two ports on my panel that I could plug into to read it. One was to the one spade from the coil module and the other went to ground. You could then read it by using a volt meter. I was able to adjust mine to 8 tenths of a degree from each other. You don't want them to be right at the same time if you are running two systems. It causes a banging sound when they both go off at the same time. It's best to have them close to a degree apart if you can.
You shouldn't try to adjust it while running the engine. It should be at 800 RPM to read it. It is very sensitive. Just tweak it a bit then start it and check it again. Believe me you can put it right on, within one tenth of a degree if you like it that close. There is only one place you should adjust it. You will see a degree scale next to the adjustment screw. The others are left alone. They are gross degree marks. They are for max RPM and over rev settings. A four cylinder Lyc. would run from 20 degrees to 25 degrees, depending on your engine model. Be sure to use only the degree setting that is on the placard on your engine. They are not all alike. Before you change anything check the data plate.
I hope this helps
Dave
----- Original Message -----
From: KMis178813 at aol.com
To: reflector at tvbf.org
Sent: Tuesday, June 09, 2009 6:04 PM
Subject: Re: REFLECTOR: CHT too cool
Chuck
The early Rose Electro Air systems (which I believe you have) do make timing adjustments based on RPM and Manifold pressure. The Base timing is set, as was previously described, if your pickup is from the mag hole. There was also another design that had a trigger wheel on the propeller end of the crank shaft. Either way the only way to set true base timing is to put the ignition system in base timing mode and use a timing light (which also requires really big Gonads!!). With the base timing set there is a dial under the cover of the control unit to adjust the base timing offset and full timing advance. One of the terminals, not normally used, can be temporarily hooked up to a volt meter in the cabin to observe what the timing advance is at any given moment. All this from memory ( Scary! ) If you need real instructions I'll need to dig the paper work out.
I'm sure it's always possible that the unit is not advancing at all?? Good thing to check every so often!!
Ken
In a message dated 6/9/2009 7:25:31 P.M. Eastern Daylight Time, michalk at awpi.com writes:
How do you change timing? Is it all in software?
I'm pretty sure only the PRISM system uses feedback of peak pressure
pulses to set timing, and all others like the ElectroAir run open loop.
How would it know what your engine requirements are?
SlvEgl99 at aol.com wrote:
> I have a Rose ElectroAir on one side. It is the old style for an IO540.
> To time it, set #1 to TDC. Insert a pin in the housing to hold the rotor
> (large gear) in position. Insert the ignition into the engine with #1 at
> TDC and the pin in place. Tighten the bolt that secures the ignition and
> then remove the pin. The ignition does adjust timing based on RPM to
> advance timing when at higher RPM.
>
> Bob Wood
>
> In a message dated 6/9/2009 4:50:01 P.M. Eastern Daylight Time,
> cjensen at dts9000.com writes:
>
> Brian,
>
> I'm running a mag on one side and a Rose Ignition on the other. I
> was under the impression that the Rose timing is supposed to be
> self-adjusting. I wonder if that's a misconception?
>
> Chuck Jensen
>
>
> -----Original Message-----
> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]On
> Behalf Of Brian Michalk
> Sent: Tuesday, June 09, 2009 11:19 AM
> To: Velocity Aircraft Owners and Builders list
> Subject: Re: REFLECTOR: CHT too cool
>
>
> Duh. It's right there.
>
> With low CHT's, it's an excellent opportunity to advance timing. Yours
> might be a little late, and advancing should bring the temps up a
> little, because you would be making more power.
>
> Chuck Jensen wrote:
> > Cylinder head temp problems are not unusual, but I have a different
> > twist. My CHT's are too cool. I can only recall once or twice
> that a
> > cylinder head ever got to 400F. Most run 350F to 390F during hot,
> > hard climbs, but at cruise, and running lean of peak, it's not
> unusual
> > for 2 to be below 300F and the rest just barely over 300F.
> >
> > Now, it well known that engines are most efficient at higher temps
> and
> > I believe Lyco's recommendation for an IO-540 K1A5 is CHTs in the
> 375F
> > to 400F temp range. This would also seem to imply that I'm suffering
> > unnecessary cooling drag from overcooling the CHs. Oil temps at
> > cruise are 195F-200F but will rise to 240F during long climbs.
> >
> > So, my question is, 'is there a way 'adjust' cooling to CHs' that may
> > reduce drag by reducing inflow through the overhead NACAs for
> > downdraft cooling, without sending the CHTs too high during climb or
> > aggravating oil temps during those climbs as well?
> >
> > Chuck Jensen
> >
> >
> >
> >
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