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pfstelwagon(at)earthlink.
Guest

Posted: Sun Oct 16, 2011 10:41 pm Post subject: yak-list: ignition timing

I don't think that one needs to worry about the fudge  factor.  The engines will run better with 2-3 degrees more timing than the  book calls for.  Remember the Chinese certified the engines for 70 octane  fuel, so with 100 octane you have a huge detonation margin.

  

 Frank CJ6-A

  [quote][b]

brian(at)lloyd.com
Guest

Posted: Mon Oct 17, 2011 7:43 am Post subject: yak-list: ignition timing

On Sun, Oct 16, 2011 at 11:37 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

 	  Quote: 	
		          I don't think that one needs to worry about the fudge  factor.  The engines will run better with 2-3 degrees more timing than the  book calls for.  Remember the Chinese certified the engines for 70 octane  fuel, so with 100 octane you have a huge detonation margin.



	




OTOH, if you get too much advance, even if you don't get detonation, you can go past the point of maximum torque, which is what you are shooting for. Since the mags on the Huosai engine have centrifugal (RPM-base) advance, I would stick with the timing settings from the factory unless you have the engine in a test cell and can measure the hook curve (change in torque with variation in timing) for your particular engine. Remember also that optimal timing (max torque) occurs at different amounts of advance at different engine loads (MAP) as well as RPM. Ever wonder why cars had vacuum advance in addition to centrifugal advance? That's why. That's another reason to want a smarter ignition system.

 



This begs the question, if you have mags with RPM-based advance available, why would anyone run fixed-timed mags? And if you have electronic ignition available that allows for variable timing with both RPM and load, why would anyone run mags at all?

 

-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)

 

  [quote][b]

nelsprague(at)hotmail.com
Guest

Posted: Mon Oct 17, 2011 2:40 pm Post subject: yak-list: ignition timing

Brian - We are getting the Yak annualed this week, any ideas?  How about an oil shut off valve? NELS

Date: Mon, 17 Oct 2011 08:41:24 -0700

Subject: Re: yak-list: ignition timing

From: brian(at)lloyd.com

To: yak-list(at)matronics.com

On Sun, Oct 16, 2011 at 11:37 PM, Frank Stelwagon <pfstelwagon(at)earthlink.net (pfstelwagon(at)earthlink.net)> wrote:

 	  Quote: 	
		          I don't think that one needs to worry about the fudge  factor.  The engines will run better with 2-3 degrees more timing than the  book calls for.  Remember the Chinese certified the engines for 70 octane  fuel, so with 100 octane you have a huge detonation margin.

OTOH, if you get too much advance, even if you don't get detonation, you can go past the point of maximum torque, which is what you are shooting for. Since the mags on the Huosai engine have centrifugal (RPM-base) advance, I would stick with the timing settings from the factory unless you have the engine in a test cell and can measure the hook curve (change in torque with variation in timing) for your particular engine. Remember also that optimal timing (max torque) occurs at different amounts of advance at different engine loads (MAP) as well as RPM. Ever wonder why cars had vacuum advance in addition to centrifugal advance? That's why. That's another reason to want a smarter ignition system.

This begs the question, if you have mags with RPM-based advance available, why would anyone run fixed-timed mags? And if you have electronic ignition available that allows for variable timing with both RPM and load, why would anyone run mags at all?

-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)

  [quote]

rget="_blank">http://www.matronics.com/Navigator?Yak-List

http://forums.matronics.com

="_blank">http://www.matronics.com/contribution

[b]

brian(at)lloyd.com
Guest

Posted: Mon Oct 17, 2011 3:05 pm Post subject: yak-list: ignition timing

On Mon, Oct 17, 2011 at 3:37 PM, Nel Sprague <nelsprague(at)hotmail.com (nelsprague(at)hotmail.com)> wrote:

 	  Quote: 	
		        Brian - We are getting the Yak annualed this week, any ideas?  How about an oil shut off valve? NELS

	




There is an automatic check valve that is supposed to keep oil from flowing back into the sump. I don't really like the idea of an oil shut-off valve but maybe it would be a good thing.

 





-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

 +1.916.877.5067 (USA)



  [quote][b]

mark.bitterlich(at)navy.m
Guest

Posted: Tue Oct 18, 2011 7:53 am Post subject: yak-list: ignition timing

Brian, sorry but I have to slightly disagree and say that I fully agree

with having one... if as a pilot you always follow a checklist, and that

you install the safety switch.      



If the check valve that you mentioned in your message did its job

correctly there would be no need to pull the prop through before start

to prevent hydraulic lock (not counting the oil that is already in the

case, etc., etc., and yes I know that can be argued, but ...) we know

that's not the case.... we ALWAYS pull the prop through.  



In addition, we also get a lot of oil that leaks past this check valve

and then out the exhaust valves and into buckets we keep under the

exhaust stacks on the floor of the hangar. 



Worse yet are tail-draggers with M-14 engines. In this case, oil can

work its way back into intake tubes, where it sits and in cold weather

does not like to come back into the cylinder and out when you pull the

prop through.  This has the possibility of being "gulped" into the

intake on start and again causing a hydraulic lock on a cold weather

start.  



Worst STILL is the fact that not all hydraulic locks cause damage that

is immediately evident.  Piston Rods can bend a little and are not easy

to find, even if you suspect it has happened.  Now you have a ticking

time bomb on your hands.  



Continuing... even with the leverage of the human arm on the end of the

prop, you have enough force pulling the engine through that you can also

bend a rod simply by trying to get oil OUT of the cylinders.     



So the check valve leaks, and yes... there are procedures for pulling

out this check valve, polishing it, and putting it back in.  This will

help with the leakage.  Now you are taking parts in and out of the oil

pump.  Screw that up once and you are in a real mess as well.  



I have seen three modifications addressing this issue.  External Oil

shut-off valves.  A Sump Pump that allows you to pump the oil out of the

sump and back into the main oil tank after engine shut-down while the

oil is still hot.  Intake port drains for the lower cylinders.  In some

cases all three are installed on the M-14 engine.  



Folks that fly their aircraft every weekend will not normally have a

need to address an issue like this.  Folks that fly their M-14's once a

month or less, WILL have this issue all the time.  Even with the intake

drains, an aircraft that has sat for a long time will usually have to

pull some sparkplugs out to drain the oil in the cylinders, which is

also a pain in the tail.  



The oil shut off valve addresses one of the big issues, and that is the

fact that the check valve in question doesn't do its job in a reliable

fashion.  So you can stick with it, and try to fix that ... and good

luck with that..... or you can go with an external shut off valve. 



The obvious danger is that you fail to turn the valve back on before

engine start.  It is a checklist item, like making sure the gear is down

before you land.  People forget doing that too once in awhile.     To

address that, a lot of the shut-off valves sold have a microswitch that

disconnects the starter wire (to the air solenoid) if the valve is left

closed.  However, if a person is really determined to be stupid, he or

she can one way or the other, get the engine started with this valve

closed, which pretty much means a new engine will be required.  



The opposite side of the coin is a bent rod, that you might not know you

have even caused, that ends up breaking in flight.  Something I have

seen happen TWICE now in my local area with this engine.  Both made it

home safely by the way, running on 8 out of 9.  



So it becomes a risk comparison evaluation, which in the end comes down

to individual choice.  The scientific discussion is how to go about

keeping oil out of the lower cylinders, or what to do about it AFTER it

gets in there.  Never-the-less, an external oil shut-off valve is indeed

one viable option. 



Mark Bitterlich



--

GeorgeCoy

Joined: 02 Dec 2010
Posts: 310

Posted: Tue Oct 18, 2011 8:04 am Post subject: yak-list: ignition timing

The Motorstar factory has developed a new replacement check valve. The

replacement is done a the factory, as the original was not designed to be

replaced. It requires removing the old valve by machining, making an

oversize hole and installing the replaceable type of check valve.  They are

also making new oil pumps with a replaceable valve installed.

George Coy



--

mark.bitterlich(at)navy.m
Guest

Posted: Tue Oct 18, 2011 8:16 am Post subject: yak-list: ignition timing

There ya go.  Of course the Housai is out of Schlitz, but ....  



George, do you possibly have something set up where a person could pull

the oil/fuel pump off their engine and have a refurbished set sent back

with this new check valve installed? 



Mark





--

george(at)gesoco.com
Guest

Posted: Tue Oct 18, 2011 9:07 am Post subject: yak-list: ignition timing

Yes I have a rebuilt one in stock for exchange. 



George Coy

CAS Ltd.

714 Airport Rd.

Swanton VT 05488

802-868-5633 off

802-363-5782 cell

802-868-4465 Fax

george.coy(at)gmail.com

http://coyafct.com/

SKYPE george.coy

--

mark.bitterlich(at)navy.m
Guest

Posted: Tue Oct 18, 2011 9:15 am Post subject: yak-list: ignition timing

As soon as budget allows, I sure will be buying one!  



Mark

--

viperdoc(at)mindspring.co
Guest

Posted: Tue Oct 18, 2011 9:23 am Post subject: yak-list: ignition timing

Interesting. Is the valve easier to access than the current one for

polishing and cleaning? Although, I must admit solvent flushed through the

oil pump with the accessory case sitting in the parts / solvent wash tank is

quiet effective at removing most of the build-up on the inner valve. But not

everyone wants to completely tear their engines down to perform this

activity. 

Otherwise it entails dropping the fuel pump then taking the oil pump off to

disassemble it completely to get to the valve that needs to

serviced/polished. Don't forget the need for new gaskets too. 

Doc



--

george(at)gesoco.com
Guest

Posted: Tue Oct 18, 2011 9:31 am Post subject: yak-list: ignition timing

Long answer NO. Same location.



George Coy

CAS Ltd.

714 Airport Rd.

Swanton VT 05488

802-868-5633 off

802-363-5782 cell

802-868-4465 Fax

george.coy(at)gmail.com

http://coyafct.com/

SKYPE george.coy

--

mark.bitterlich(at)navy.m
Guest

Posted: Tue Oct 18, 2011 10:44 am Post subject: yak-list: ignition timing

Or, you can simply go with an external valve ......   Hence the point?

   



That said: I like the idea of a better valve, and I'll get one.

Especially when I consider I am getting an overhauled assembly in

exchange.  A good thing.  

  



Mark



--

brian(at)lloyd.com
Guest

Posted: Tue Oct 18, 2011 1:10 pm Post subject: yak-list: ignition timing

On Tue, Oct 18, 2011 at 2:01 PM, Brian Lloyd <brian(at)lloyd.com (brian(at)lloyd.com)> wrote:

 	  Quote: 	
		   



On Tue, Oct 18, 2011 at 8:50 AM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

   	  Quote: 	
		  --> Yak-List message posted by: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>

   

 Brian, sorry but I have to slightly disagree and say that I fully agree

 with having one... if as a pilot you always follow a checklist, and that

 you install the safety switch.

	


Actually, that was supposed to be a private message. I didn't realize that Nels had posted to the Yak list. I thought it was a private EM to me and I just hit reply.

 

	




My general feeling is that almost any modification needs a lot more thought than most people give it. George Coy's and Motorstar's approach of fixing the valve that is already in there appeals to me much more than retrofitting an additional valve. But that is just me.

 

-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)

 

  [quote][b]

mark.bitterlich(at)navy.m
Guest

Posted: Wed Oct 19, 2011 7:36 am Post subject: yak-list: ignition timing

On Tue, Oct 18, 2011 at 2:01 PM, Brian Lloyd <brian(at)lloyd.com> wrote:

 	  Quote: 	
		  Actually, that was supposed to be a private message. I didn't realize

that Nels had posted to the Yak list. I thought it was a private EM to
	


me and I just hit reply."



Roger that.  



 	  Quote: 	
		  My general feeling is that almost any modification needs a lot more

thought than most people give it. George Coy's and Motorstar's approach
	


of fixing the valve that is already in there appeals to me much more

than retrofitting an additional valve. But that is just me.



Replacing the valve in the oil pump with a better one appeals to me as

well.  Even though it means MODIFYING THE OIL PUMP!   However one of the

things that I use to weigh the value of a modification is: Has it been

done before for the same reasons anywhere else? 



The answer to that is that many aircraft that employed radial engines

used an external oil shutoff valve to prevent the very problem discussed

here., so this is not exactly a "new idea".   Some of these valves were

electro-mechanical, some purely mechanical, and some without any kind of

safety interface at all.  One that comes immediately to mind is the

Douglas A-26 Invader.  Recently, an A-26 south of here had a breaker

blow that prevented that valve from opening before flight.  Both engines

were ruined.  



So the potential to destroy an engine with an external oil shut-off

valve is certainly there.  



That said, I again reiterate that bending rods is very easy to do with

the M-14 engine.  I've personally seen it happen to two of them.  I have

yet to see anyone fail to open an externally controlled oil valve, but I

am sure it will probably happen someday.  I also will note that in my

PERSONAL opinion, I get a rather bad feeling whenever someone (anyone)

starts messing around with my fuel and oil pump.  This kind of

maintenance action is exactly the kind of thing that brought that

YAK-50's engine to a complete stop in flight over England some months

back.  I trust George.  There are very few others though that I would.  



It's a toss-up, but my choice would be an external valve that I can see

with my own two eyes, that I know works exactly as it should because I

helped put it in there and checked it out.  But... that's just me (as

well).    



Mark

brian(at)lloyd.com
Guest

Posted: Wed Oct 19, 2011 8:02 am Post subject: yak-list: ignition timing

On Wed, Oct 19, 2011 at 8:32 AM, Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)> wrote:

  	  Quote: 	
		  --> Yak-List message posted by: "Bitterlich, Mark G CIV Det Cherry Point, MALS-14 64E" <mark.bitterlich(at)navy.mil (mark.bitterlich(at)navy.mil)>

  

 

 

On Tue, Oct 18, 2011 at 2:01 PM, Brian Lloyd <brian(at)lloyd.com (brian(at)lloyd.com)> wrote:

 

 

 

 	  Quote: 	
		  Actually, that was supposed to be a private message. I didn't realize

 that Nels had posted to the Yak list. I thought it was a private EM to
	


 me and I just hit reply."

 

 

Roger that.

 

 >My general feeling is that almost any modification needs a lot more

 thought than most people give it. George Coy's and Motorstar's approach

 of fixing the valve that is already in there appeals to me much more

 than retrofitting an additional valve. But that is just me.

 

 

Replacing the valve in the oil pump with a better one appeals to me as

 well.  Even though it means MODIFYING THE OIL PUMP!   However one of the

 things that I use to weigh the value of a modification is: Has it been

 done before for the same reasons anywhere else?

	




We have had this debate (argument?) before. The engine has a valve specifically intended to keep oil from pooling in the engine when the engine is not running. My personal feeling is that it makes more sense to ensure that the designed-in valve does its job rather than duplicating the function using an external valve. 

 



Analogy: if you have an on-off switch in a device that has a tendency to fail you replace it with a switch that works properly and doesn't fail. You don't add another switch in the power cord. 

 



But as I said, that is just me. I am interested in hearing about the improvements to the internal check valve in the oil pump. I am not interested in debating the efficacy of one type of oil shut-off vs. another. YMMV.

 



-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com (brian(at)lloyd.com)

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)

 

  [quote][b]

mark.bitterlich(at)navy.m
Guest

Posted: Wed Oct 19, 2011 8:26 am Post subject: yak-list: ignition timing

 	  Quote: 	
		  We have had this debate (argument?) before. The engine has a valve

specifically intended to keep oil from pooling in the engine when the
	


engine is not running. My personal feeling is that it makes more sense

to ensure that the designed-in valve does its job rather than

duplicating the function using an external valve. 



Ok, then REMOVE the internal valve and replace it with an EXTERNAL

valve.  My personal feeling is that the whole original design is wrong

to begin with.  An engineer should not design an internal valve that

requires removing the fuel pump and the oil pump from the engine in

order to service or repair the darn thing, when it serves a function

that can impact the safety and health of the engine to begin with.  Yes,

we have debated/discussed it before, but come on now Brian, that has

never stopped either of us has it?  Yes, a lot of folks like to take

individual parts used in a design and improve on them.  Sometimes

though, it is better to step even FURTHER back and discuss whether the

design was even sound to begin with.  I don't like that check valve at

all, and I also don't like where it is located.  



 	  Quote: 	
		  Analogy: if you have an on-off switch in a device that has a tendency

to fail you replace it with a switch that works properly and doesn't
	


fail. You don't add another switch in the power cord. 



No, but you sometimes chop out the one that is giving you trouble and

mount another one where it is much easier to get to if and when it

fails, don't you?  



What George Coy said was this: " The Motorstar factory has developed a

new replacement check valve. The replacement is done a the factory, as

the original was not designed to be replaced. It requires removing the

old valve by machining, making an oversize hole and installing the

replaceable type of check valve.  They are also making new oil pumps

with a replaceable valve installed."  



I *THINK* what he meant by this (are you there George?) was that the new

type installation now allows you to CHANGE the valve when it fails.

Question:  Can this be accomplished by accessing the valve with the

accessory drive section that includes the oil and fuel pump remaining on

the engine or not?  If you can pop this valve out and replace it without

taking the whole mess apart, that would be super.  If not, then it just

means you can change it when it goes bad instead of just trying to

polish up the ball.  



 	  Quote: 	
		  But as I said, that is just me. I am interested in hearing about the

improvements to the internal check valve in the oil pump. I am not
	


interested in debating the efficacy of one type of oil shut-off vs.

another. 



The original message brooked the question of whether an external oil

shut-off valve was worthy of consideration.  If you are not interested

in discussing or debating the efficacy of that question, simply don't

respond.  



 Mark





-- 

Brian Lloyd, WB6RQN/J79BPL

3191 Western Dr.

Cameron Park, CA 95682

brian(at)lloyd.com

+1.767.617.1365 (Dominica)

+1.916.877.5067 (USA)

Rob Rowe

Joined: 10 Jan 2006
Posts: 124
Location: Berkshire, UK

Posted: Thu Oct 20, 2011 4:46 am Post subject: Re: yak-list: ignition timing (now oil pump design)

FWIW - there are two valves in the M14P oil pump, a check valve and a pressure relief valve.



My understanding of their function is as follows (relying on Dennis et al to keep me honest here) ...



Check Valve (CV) - located at output of oil pressure pump, opens on oil pressure against spring loaded valve. Purpose is to close off oil flow through pump on shutdown. Inaccessible for cleaning let alone replacement. Fortunately usually reliable in operation and causes little seepage unless contaminated.



Pressure Relief Valve (PRV) - also operates on output of oil pressure pump (effectively in parallel with check valve), field adjustable spring pressure regulates oil output pressure with surplus returned to pump input. On shutdown it too needs to seal to prevent oil flow through pump. Both valve and spring are accessible in-situ. Valve design could be better as hard valve seat (square cut) wears a groove in softer valve head chamfer, this does not impact its pressure relief operation and if this was the only issue should seal reasonably well on shutdown. However situation exacerbated by using a relatively long spring with a locating spigot (on top of valve) significantly narrower than the spring diameter. This combination allows spring 'S' deformation resulting in lateral as well as vertical pressure applied to the valve, as evidenced by valve stem finish wear on diametrically opposing sides top & bottom. Net result is groove worn in valve head is of variable breadth & depth that allows oil seepage on shutdown, that progressively worsens with usage. While this can be 'polished' out to a degree a better solution would be a redesigned valve and spring (with more accurate flat end grinding) to reduce the lateral forces and resulting uneven wear.



So I'll be interested to see which valve Motorstar have modified  - if it's the CV then no question oil pump exchange, but don't believe this will greatly improve the situation as this is generally reliable. If it's the PRV then a valve/spring redesign might be in-situ, but if the valve seat has also been altered then an exchange job ... IMHO.



Brgds, Rob R.

GeorgeCoy

Joined: 02 Dec 2010
Posts: 310

Posted: Thu Oct 20, 2011 5:00 am Post subject: yak-list: ignition timing

They developed a way to replace the CV valve. The PRV valve seat is also

machined at overhaul.

George



--

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