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  #51  
Old 12-30-2017, 02:41 PM
mfshook62 mfshook62 is offline
 
Join Date: Sep 2008
Location: Windsor, Ca
Posts: 102
Default Using the "A" Curve

I have a question. I am using the "A" curve (jumper) on my 2 PMags. The manual states, that when using the "A" curve, the ignition follows the Base Curve alone, and also, any EICAD changes to the advance shift changes the "B" curve only.

So, when folks mention setting the advance to -1.4 deg, they are talking about using the "B" curve?
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  #52  
Old 12-30-2017, 05:12 PM
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revenson revenson is offline
 
Join Date: Mar 2005
Location: Tucson, AZ
Posts: 156
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No. Without the jumper in, and with advance shift set to 0 via EICAD, that is the same as the A curve. So then -1.4 (1 click) is slightly retarded from 'A' curve.
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  #53  
Old 12-30-2017, 08:30 PM
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GalinHdz GalinHdz is offline
 
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Location: KSGJ / TJBQ
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Quote:
Originally Posted by Bevan View Post
Without EICAD, retarding the timing by 1.4 degrees would be approximately 1/2 tooth on the ring gear? Ring gear is 149 teeth. Is this an acceptable method?

Bevan
Interesting that several years ago, and after many months of experimenting (Parallel valve Lycoming with 8.5 compression, dual P-Mag installation "A" curve) I found it worked best if I set the timing just past 1/2 tooth ATDC. I never understood why but now at least I have a plausible explanation.

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Last edited by GalinHdz : 12-30-2017 at 08:37 PM.
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  #54  
Old 12-30-2017, 09:24 PM
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N941WR N941WR is offline
 
Join Date: Jan 2005
Location: SC
Posts: 11,286
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Quote:
Originally Posted by mfshook62 View Post
I have a question. I am using the "A" curve (jumper) on my 2 PMags. The manual states, that when using the "A" curve, the ignition follows the Base Curve alone, and also, any EICAD changes to the advance shift changes the "B" curve only.

So, when folks mention setting the advance to -1.4 deg, they are talking about using the "B" curve?
The A configuration cannot be changed with the EICAD program. Only the B configuration (or memory location) can be changed.

However, you can change the B configuration to look like the A configuration and then set that to a negative 1.4. If you do that, DO NOT install the jumper as you want the P-mags to run on the B configuration that you have just customized.
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  #55  
Old 01-01-2018, 07:01 PM
Doug Eves Doug Eves is offline
 
Join Date: Dec 2007
Location: Brigden Ontario Canada
Posts: 60
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RV6/io-360/constant speed/57 hrs on 2 Pmags with auto plugs. Flawless so far/Super smooth , stars awesome but I use the same fuel flow as before on purpose as my engine is in great shape after 835 hrs and I don't want to experiment with the lop thing for the sake of a bit of avgas. I think it makes more hp as well but hard to quantify.
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  #56  
Old 01-02-2018, 06:10 AM
pa38112 pa38112 is offline
 
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Location: Clarksboro, NJ
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Quote:
Originally Posted by Doug Eves View Post
RV6/io-360/constant speed/57 hrs on 2 Pmags with auto plugs. Flawless so far/Super smooth , stars awesome but I use the same fuel flow as before on purpose as my engine is in great shape after 835 hrs and I don't want to experiment with the lop thing for the sake of a bit of avgas. I think it makes more hp as well but hard to quantify.
LOP is better for your engine, and that is a fact. It produces less oil contamination, less valve fouling, less chance of ring issues, lower occurrences of induction leaks. You have an IO with P-mags. I would suggest you are crazy not running LOP. It is not experimentation - just education. Research it a bit and see what you think.
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  #57  
Old 01-02-2018, 10:10 PM
Doug Eves Doug Eves is offline
 
Join Date: Dec 2007
Location: Brigden Ontario Canada
Posts: 60
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Well... I run around at relatively low altitudes at 25 square. Been doing that for 835 hrs and my engine is super clean internally(use XD3 15w40) with great compression etc. Check for wear metals on oil in and out at the good old ESSO inspection lab where I worked for 37 years right beside a state of the art engine test faciliity that I frequented. I have read lots on lean of peak. I don't mind at lower power settings but I just don't want to change my approach.
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  #58  
Old 01-02-2018, 10:18 PM
Doug Eves Doug Eves is offline
 
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Location: Brigden Ontario Canada
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And yes I have been told I am crazy... But not for the way I treat engines. I have looked inside tons of them after they have been experimented on with different oils , temps ,mixtures, ect. Av oil sucks and HD diesel oil keeps everything spotless internally not to mention the wear protection of our ancient engines. Not saying lean of peak is bad , just don't want to go there at 25 square for some crazy internal reason
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  #59  
Old 01-03-2018, 02:03 AM
rv8ch rv8ch is offline
 
Join Date: Feb 2005
Location: LSGG
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Default Diesel oil

Quote:
Originally Posted by Doug Eves View Post
And yes I have been told I am crazy... But not for the way I treat engines. I have looked inside tons of them after they have been experimented on with different oils , temps ,mixtures, ect. Av oil sucks and HD diesel oil keeps everything spotless internally not to mention the wear protection of our ancient engines. Not saying lean of peak is bad , just don't want to go there at 25 square for some crazy internal reason
Never heard of using diesel oil in a lycoming - Doug does not think it's a good idea: http://www.vansairforce.com/communit...95&postcount=8 due to the ZDDP:

Quote:
ZDDP is not your friend in traditional Ly-Cons because the temperatures in the valve areas is too hot for the ZDDP additives. They come apart into some very nasty compounds that are acidic and will cause horrible deposits in your engine.
Perhaps you are running diesel oil with a different anti-wear additive?
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  #60  
Old 01-04-2018, 02:54 PM
Doug Eves Doug Eves is offline
 
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Location: Brigden Ontario Canada
Posts: 60
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Emag thread drift however...Essolube Xd3 15w40 (EXXON for you) and Shell's rotella t are designed/formulated for either gas or diesel severe duty , high friction type applications.(flat tappet engines) it does have P and Zn in the add pack along with a bunch of other additives. If you want a spotless engine(internally) being highly protected from wear then use it. The oil certainly doesn't know a lycoming from a cummings. It just cleans and protects. (way better than "aviation" oil). Sorry that the facts. 37 years for Imperial oil looking inside hundreds of disassembled test engines.
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