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wnorth(at)sdccd.edu
Guest

Posted: Mon Dec 24, 2007 7:24 pm Post subject: timing

Hi Linn,



I would partly disagree with you about the timing. The most critical thing

is that both mags are equal, but if they are slightly off of 25 it just

means the engine will be most efficient at a slightly different RPM. Since

we don't know what that was when set at 25 it really doesn't matter.



I've found that setting them at 23 brought chts down by 20 deg and egts up

by about 50-75



But they should be within .5 deg of each other.



There's an SB on 0-360-A1A's installed in Mooney's, I think, which allows

for them to be set all the way back to 20.



W

Kellym

Joined: 10 Jan 2006
Posts: 1706
Location: Sun Lakes AZ

Posted: Mon Dec 24, 2007 8:12 pm Post subject: timing

It is a service instruction, not a bulletin, and it is for 200 hp IO360s 

regardless of airframe.

It requires internal modification to the mags, so that starting timing 

remains at TDC while cruise timing is 20 degrees. You will cause 

problems if you just dial it back to 20 degrees.

The change was to reduce peak cylinder pressures for extreme cold temp 

operations to prevent cylinder heads from flying off the engine, dates 

back to the late seventies.

Not applicable to the lower compression O-360 engines.



Wheeler North wrote:

 	  Quote: 	
		   



 Hi Linn,



 I would partly disagree with you about the timing. The most critical thing

 is that both mags are equal, but if they are slightly off of 25 it just

 means the engine will be most efficient at a slightly different RPM. Since

 we don't know what that was when set at 25 it really doesn't matter.



 I've found that setting them at 23 brought chts down by 20 deg and egts up

 by about 50-75



 But they should be within .5 deg of each other.



 There's an SB on 0-360-A1A's installed in Mooney's, I think, which allows

 for them to be set all the way back to 20.



 W

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

wnorth(at)sdccd.edu
Guest

Posted: Tue Dec 25, 2007 9:35 am Post subject: timing

While all of that is true the inherent point was the engine will run just

fine at altered timing, particularly just off a degree or two. And in fact

may run a bit better with respect to chts and or egts depending on how well

your airplane is cooling. I back mine down to 23 during summer and kick it

up to 25 during winter.



However the mags should fire at as close a time as possible. It is one

reason I'm not in favor of running one mag and one variable ECM base

ignition system. It is probably not too bad when they fire very differently

as the later spark is wasted, but when they are firing close, heaven only

knows what that does to the flame front, balanced piston loads, and

potential detonation issues.

n616tb(at)btsapps.com
Guest

Posted: Tue Dec 25, 2007 10:12 am Post subject: timing

Wow this thread has become very interesting.  My timing was actually about

26 degrees on one mag and closer to 24 on the second mag.  I have had high

CHT's all along and have done everything I can think of to get my temps down

without full success.  I installed louvers in the cowl, sealed around my

baffles with goup, put a door behind my oil cooler and closed off one of my

heater intakes.  I still after settling into cruise get about 399-405

degrees for CHT's with oil temps around 185.



Now I have changed my timing to be right together at 25 degrees.  I have not

flown yet, but when summer comes around I may very well try adjusting it to

about 23 to see what happens.



Tim



[quote] --

ronlee(at)pcisys.net
Guest

Posted: Tue Dec 25, 2007 11:44 am Post subject: timing

Tim, what is your compression ratio?  If around 9.5:1 what I have read

states that timing should be 20 degrees BTDC.



Ron Lee

n616tb(at)btsapps.com
Guest

Posted: Tue Dec 25, 2007 12:17 pm Post subject: timing

I don't know right now.  It is standard 0-360 however.  I will look later

when I get back home.  My data tag from Aero Sport says 25 BTDC.

Tim



[quote] --

bobbyhester(at)newwavecom
Guest

Posted: Tue Dec 25, 2007 3:07 pm Post subject: timing

Tim, your the first one I've heard of that has the exact same thing as I do. In cruise on 80-90 degree days I have about 400 CHTs and on climb out I have to level off about 1500 ft and pull back the throttle when the CHTs get to about 430 degrees. I've done the same things that you have, checked timing, checked baffles, put the louvers in the bottom of the cowl. I have a Superior XPO360 with one mag and one lightspeed.

  	  Quote: 	
		  ----

Surfing the web from Hopkinsville, KY

Visit my flying RV7A web page:

http://home.newwavecomm.net/bobbyhester/MyFlyingRV7A.htm



	
 

 

 Tim Bryan wrote: [quote]   [quote]--> RV-List message posted by: "Tim Bryan" <n616tb(at)btsapps.com> (n616tb(at)btsapps.com)



Wow this thread has become very interesting.  My timing was actually about

26 degrees on one mag and closer to 24 on the second mag.  I have had high

CHT's all along and have done everything I can think of to get my temps down

without full success.  I installed louvers in the cowl, sealed around my

baffles with goup, put a door behind my oil cooler and closed off one of my

heater intakes.  I still after settling into cruise get about 399-405

degrees for CHT's with oil temps around 185.



Now I have changed my timing to be right together at 25 degrees.  I have not

flown yet, but when summer comes around I may very well try adjusting it to

about 23 to see what happens.



Tim



       [quote]--

acepilot(at)bloomer.net
Guest

Posted: Tue Dec 25, 2007 7:12 pm Post subject: timing

If I recall, my small Continentals (65 & 85) have different timings that 

are 2 degrees apart...something like 28 on the left and 30 on the right 

maybe?



Scott

http://corbenflyer.tripod.com/

Gotta Fly or Gonna Die

Building RV-4 (Super Slow Build Version)



Tim Bryan wrote:



[quote]



Wow this thread has become very interesting.  My timing was actually about

26 degrees on one mag and closer to 24 on the second mag.  I have had high

CHT's all along and have done everything I can think of to get my temps down

without full success.  I installed louvers in the cowl, sealed around my

baffles with goup, put a door behind my oil cooler and closed off one of my

heater intakes.  I still after settling into cruise get about 399-405

degrees for CHT's with oil temps around 185.



Now I have changed my timing to be right together at 25 degrees.  I have not

flown yet, but when summer comes around I may very well try adjusting it to

about 23 to see what happens.



Tim



  



>--

Kellym

Joined: 10 Jan 2006
Posts: 1706
Location: Sun Lakes AZ

Posted: Tue Dec 25, 2007 8:59 pm Post subject: timing

The standard O-360 parallel valve engine is 8.5 to 1 in its certified 

configuration. YMMV if anyone did modifications.



Tim Bryan wrote:

[quote] 



 I don't know right now.  It is standard 0-360 however.  I will look later

 when I get back home.  My data tag from Aero Sport says 25 BTDC.

 Tim



   

> --

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

N122RL(at)aol.com
Guest

Posted: Wed Dec 26, 2007 5:31 am Post subject: timing

Try running on the lightspeed only. I have the same setup but with a O320. The temps on my engine come right down when I run on lightspeed only. Have no idea why.

  

 Bob 



See AOL's top rated recipes and easy ways to stay in shape for winter.

  [quote][b]

dale1rv6(at)comcast.net
Guest

Posted: Wed Dec 26, 2007 6:34 am Post subject: timing

IMHO; there must be an interesting mystery going on when 99% of the RVs run below 380 CHT and a few don’t. I don’t think it is because 99% have great baffles. Check all assumptions, verify every detail for timing. Make sure you have the correct reference points on both engine and flywheel. Verify accuracy of CHT gauge and probe. A one square inch hole in baffle is not good, but it will not raise CHT temps by 20 degrees, I have tested that. The best way to overheat an engine is to increase advance timing too much for a given MP and rpm. Bob, your results are a strong indication that the mag is accidentally too advanced, possibly defective. “Still” timing checks are not proof that the mag is working correct at running speed (if the mag is defective). The proper power & temperature on the lightspeed only operation is a strong indication that you don’t have a cooling problem, you have a mag or mag timing problem. Your results also indicate your CHT gauge is OK. IMHO  

Don’t give up your search.  

Best of luck,  

Dale  

   

Do not archive        

  

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of N122RL(at)aol.com

 Sent: Wednesday, December 26, 2007 8:29 AM

 To: rv-list(at)matronics.com

 Subject: [Norton AntiSpam] Re: timing  

  

     

Try running on the lightspeed only. I have the same setup but with a O320. The temps on my engine come right down when I run on lightspeed only. Have no idea why.  

    

   

    

Bob   

  



 

         

  

See AOL's top rated recipes and easy ways to stay in shape for winter.  

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n616tb(at)btsapps.com
Guest

Posted: Wed Dec 26, 2007 7:40 am Post subject: timing

Hi Bobby,  

   

Have any of those things you did made a difference?  The baffles made the biggest difference for me but not enough in my opinion.  In summer I am at over 460 degrees after climb out at 110 mph initially then lowering the nose to about 130.  I don’t have to climb to more than 4 or 5,000 to be this hot.  The louvers made the biggest difference in cruise as I was cruising at nearly 425 degrees and after the louvers it is pretty close to 400.   

   

I haven’t given up on finding the reason my engine runs hotter than everyone else with the exact same thing, but I have run out of ideas.  What do you have your timing set to?  

Tim  

           

  

From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Bobby Hester

 Sent: Tuesday, December 25, 2007 4:45 PM

 To: rv-list(at)matronics.com

 Subject: Re: timing  

  

   

Tim, your the first one I've heard of that has the exact same thing as I do. In cruise on 80-90 degree days I have about 400 CHTs and on climb out I have to level off about 1500 ft and pull back the throttle when the CHTs get to about 430 degrees. I've done the same things that you have, checked timing, checked baffles, put the louvers in the bottom of the cowl. I have a Superior XPO360 with one mag and one lightspeed.

 

    	  Quote: 	
		  ----Surfing the web from Hopkinsville, KYVisit my flying RV7A web page:http://home.newwavecomm.net/bobbyhester/MyFlyingRV7A.htm 	
  



 

 Tim Bryan wrote:    	  Quote: 	
		  --> RV-List message posted by: "Tim Bryan" <n616tb(at)btsapps.com> Wow this thread has become very interesting.  My timing was actually about26 degrees on one mag and closer to 24 on the second mag.  I have had highCHT's all along and have done everything I can think of to get my temps downSurfing the web from Hopkinsville, KY 	
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n616tb(at)btsapps.com
Guest

Posted: Wed Dec 26, 2007 7:44 am Post subject: timing

Hi Ron,



I can't find anything that indicates my compression ratio.  I purchased it

from Aerosport Power and did not specify anything but standard so I can only

presume it is the 8.5 : 1 somebody referred to.



Tim



[quote] --

recapen(at)earthlink.net
Guest

Posted: Wed Dec 26, 2007 8:08 am Post subject: timing

The piston part numbers may be able to help - there should be a list of components in your documentation.



I got 9.2:1 with mine.....



--

klwerner(at)comcast.net
Guest

Posted: Wed Dec 26, 2007 9:05 am Post subject: timing

Tim,

 Then you highly likely have the std.  compression ratio for this engine. 

 You may want to check with Bart  to verify it directly from the source.

 do not archive

 [quote]   ---

ronlee(at)pcisys.net
Guest

Posted: Wed Dec 26, 2007 9:07 am Post subject: timing

Most likely you have 8.5:1



Ron Lee



do not archive

---

n1cxo320(at)salidaco.com
Guest

Posted: Wed Dec 26, 2007 9:18 am Post subject: Timing

FWIW - I have an O-320-160 HP  w/ fixed prop  and was runniing two Lightspeed electronic ignition systems. I was fighting high  oil temps and not making progress. Installed larger oil cooler. No help. Put in  a cowl flap to more more air out of the cowl enclosure. No help. Improved  sealing around top of baffles where they met the top cowling. No help. Did all  sorts of other little things. No help.

  

 In desperation I began to re-read Lightspeed  instructions. My O-320 is a 160HP so I assumed it "qualified" as high  compression as Klaus describes it in his instructions, thus requiring timing set  to 5-degrees BTDC. It turns out the 8.5:1 is not "high compression" as he  defines it, so I set the timing to zero-degrees, or TDC and the high oil temps  went away. I now see CHT and oil temps in the low part of normal range, and  don't need the cowl flaps. On a hot day in climb I rarely see over 205-F in the  oil temps, and cruise is typically 190-195.

  

 Why the 5-degree diffference in timing would make  such a great difference seems strange, but I won't argue with a good  outcome.

  

  

   [quote][b]

jrdial(at)hal-pc.org
Guest

Posted: Wed Dec 26, 2007 9:24 am Post subject: timing

                 I have the same engine you have with 8.5-1 compression and one Lightspeed and one mag. I had the same problem and it ended up being a crack in the vacuum line that goes to the Lightspeed ignition. I have no heating problem even in the plus 100 degree days we have near Austin, TX.  

                        I have the crank trigger mounted in the flywheel. I did check the timing on both ignitions before I discovered the vacuum leak.  

   

   

   

   

--

klwerner(at)comcast.net
Guest

Posted: Wed Dec 26, 2007 9:42 am Post subject: Timing

John,

 Wouldn't a high compression engine be  timed to fire later (TDC) then a standard compression engine  (5-BTDC)? 

 I think you may have had it at the  standard compression setting earlier and now run it at the high  compression setting.  

 Either way, your problems went away  by going to 0 degrees/TDC...  

 do not archive

 [quote]   ---

wnorth(at)sdccd.edu
Guest

Posted: Wed Dec 26, 2007 11:49 am Post subject: Timing

There are a few engines that stagger timing slightly but the presumption is

that the manufacturer has decided that it improves the flame propagation and

has demonstrated that is does nothing harmful. If I remember correctly these

are mostly low compression engines.



I would be cautious going much below 22-23 degrees without some form of

"every" cylinder cht/egt monitoring.



By firing things a tad later one moves the flame process more towards the

exhaust cycle which means more heat goes that way and less goes into the

heads. One would not think it is that much but on a heat critical engine it

can be. Many of the 0-360 RVs do not possess the CHT cooling exchange to

climb out indefinitely. There was a line of Mercedes engines years ago that

would over-heat in 15 minutes irrespective of operating conditions if the

timing was not within a 3 deg range across its entire timing curve. I once

overhauled one of those engines twice learning this. The fix was to clean up

the gummed up centrifugal timing advance weights and get the timing dead on.



One critically important thing to do is make sure the flashing from casting

in the fin holes between the spark plugs is completely cleared out. Doing

this gave me 20 degs on the two cylinders which were fairly bad and 10 on

the one that was kinda bad. 



All the opening and exit tweeks I tried did nada and the one thing I've

wanted to try but am not up to downing the airplane for that long, is to

increase the pressure reservoir size of the upper chamber. I have an

internal baffle roof which I think I can greatly improve upon but, that is a

lot of work that is a 50/50 shot at doing anything useful.

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