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M-14b Timing

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Michael Bolton

Joined: 31 May 2007
Posts: 9

Posted: Tue Oct 02, 2007 5:09 am Post subject: M-14b Timing

Does anyone out there know the initial Mag timing  for the M-14b?  yes that is a "B"  I only have the manual for the P  model.  The "B" has mags with centerfugal advance.  

  

 Thanks for any help you guys might be able to  supply. 

  

 Michael J. Bolton, Vice President

Young Forest  Products, Inc.

(O)803.438.4259

(C)803.427.0604

    [quote][b]

dsavarese(at)elmore.rr.co
Guest

Posted: Tue Oct 02, 2007 5:33 am Post subject: M-14b Timing

I'm working on it Michael and will get back to you with the  information.

 Dennis

  

 [quote]   ---

cliff(at)gesoco.com
Guest

Posted: Tue Oct 02, 2007 10:39 am Post subject: M-14b Timing

The  spark advance for  the M14 series engines is  22-24 degrees BTDC.

 

If you have M9-35M magnetos, there is a degree stamp on the mating face 

of the magneto body under the mag cap.

This stamp is typically between 23 and 37 degrees.



To compensate for the centrifugal advance of the mag use the following 

formula:



23 - (degree stamp / 1.25) = timing mark on the cylinder pointer in #4 

cylinder.



If you're timing the engine via prop flange, then you will need to 

multiply the above result by the reduction gear ratio.



On M14-P it's .658

On M14-B it's .787



So....with a "36" degree stamped magneto-



23- (36/1.25) = -5.8 or 6 degrees *after* top dead center as seen on the 

cylinder pointer.



at the prop flange of an M14-P: 5.8 * .658 = 3.8 or 4 degrees ATDC

at the prop flange of an M14-B: 5.8 * .787 = 4.5 degrees ATDC



Cheers,

Cliff

Michael Bolton wrote:



 	  Quote: 	
		   Does anyone out there know the initial Mag timing for the M-14b?  yes 

 that is a "B"  I only have the manual for the P model.  The "B" has 

 mags with centerfugal advance. 

  

 Thanks for any help you guys might be able to supply.

  

 Michael J. Bolton, Vice President

 Young Forest Products, Inc.

 (O)803.438.4259

 (C)803.427.0604



*

*

dsavarese(at)elmore.rr.co
Guest

Posted: Tue Oct 02, 2007 1:56 pm Post subject: M-14b Timing

The only thing I would add is be sure the Mags are M9-35's as stamped on the 

data plate just above the P lead and coil cover.  If they are other than the 

M9-35's, please post to the list.

Dennis



---

wlannon(at)cablerocket.co
Guest

Posted: Tue Oct 02, 2007 3:17 pm Post subject: M-14b Timing

Dennis;



They could be M9-25M mags (23 to 27 degs of advance) on the M14B. I suspect 

that the "B" is a lower RPM engine than the "M".  In any case Cliff's 

instructions would still apply.



Walt

---

dsavarese(at)elmore.rr.co
Guest

Posted: Tue Oct 02, 2007 4:35 pm Post subject: M-14b Timing

That's what I believe they are Walt.  But I certainly could be wrong.

Dennis



---

wlannon(at)cablerocket.co
Guest

Posted: Tue Oct 02, 2007 10:06 pm Post subject: M-14b Timing

Hi Cliff;



Could you expand on the use of the factor of  "/1.25" in calculating the 

ignition advance angle?

What does that factor represent?

Thanks.

Walt

---

cliff(at)gesoco.com
Guest

Posted: Wed Oct 03, 2007 4:13 am Post subject: M-14b Timing

Cliff had an oops.

I got my engines crossed between M462 and M14B.

I was going from memory about gear reduction ratio for the M14-B engine.

I'll go hit the books and make a final determination if needed.

Doug pointed out that many people are running the "B" engine with a "P" 

nose case which makes the point moot anyway.

In any event, if you time by the sparkplug pointer, then the gear 

reduction doesn't come into play.

Cheers,

Cliff

In any event

Cliff Coy wrote:

 	  Quote: 	

 The  spark advance for  the M14 series engines is  22-24 degrees BTDC.

 If you have M9-35M magnetos, there is a degree stamp on the mating 

 face of the magneto body under the mag cap.

 This stamp is typically between 23 and 37 degrees.

 To compensate for the centrifugal advance of the mag use the following 

 formula:

 23 - (degree stamp / 1.25) = timing mark on the cylinder pointer in #4 

 cylinder.

 If you're timing the engine via prop flange, then you will need to 

 multiply the above result by the reduction gear ratio.

 On M14-P it's .658

 On M14-B it's .787

 So....with a "36" degree stamped magneto-

 23- (36/1.25) = -5.8 or 6 degrees *after* top dead center as seen on 

 the cylinder pointer.

 at the prop flange of an M14-P: 5.8 * .658 = 3.8 or 4 degrees ATDC

 at the prop flange of an M14-B: 5.8 * .787 = 4.5 degrees ATDC

 Cheers,

 Cliff

 Michael Bolton wrote:

> Does anyone out there know the initial Mag timing for the M-14b?  yes 

> that is a "B"  I only have the manual for the P model.  The "B" has 

> mags with centerfugal advance.  

> Thanks for any help you guys might be able to supply.

>  

> Michael J. Bolton, Vice President

> Young Forest Products, Inc.

> (O)803.438.4259

> (C)803.427.0604

>

> *

> *

>

cliff(at)gesoco.com
Guest

Posted: Wed Oct 03, 2007 4:32 am Post subject: M-14b Timing

The mag turns 1.25 times per crank revolution.



Dividing the retard angle by the drive ratio gives the offset from 

"running" position of the rotor-which is what you are ultimately timing to.



To verify this, we can take an M9-F magneto with 0 retard angle and run 

it through the formula:



23 - (0/1.25) * .658 = 15.1



So 23 degrees BTDC (crank position) translates to 15 degree BTDC (prop 

flange position).



Cheers,

Cliff



Walter Lannon wrote:



[quote] 



 Hi Cliff;



 Could you expand on the use of the factor of  "/1.25" in calculating 

 the ignition advance angle?

 What does that factor represent?

 Thanks.

 Walt

 ---

cliff(at)gesoco.com
Guest

Posted: Wed Oct 03, 2007 9:51 am Post subject: M-14b Timing

Hey...add another 1 in there...that should read



"the mag turns 1.125 times per crank revolution"



<sigh>



Cliff Coy wrote:



[quote] 



 The mag turns 1.25 times per crank revolution.



 Dividing the retard angle by the drive ratio gives the offset from 

 "running" position of the rotor-which is what you are ultimately 

 timing to.



 To verify this, we can take an M9-F magneto with 0 retard angle and 

 run it through the formula:



 23 - (0/1.25) * .658 = 15.1



 So 23 degrees BTDC (crank position) translates to 15 degree BTDC (prop 

 flange position).



 Cheers,

 Cliff



 Walter Lannon wrote:



> 

> <wlannon(at)cablerocket.com>

>

> Hi Cliff;

>

> Could you expand on the use of the factor of  "/1.25" in calculating 

> the ignition advance angle?

> What does that factor represent?

> Thanks.

> Walt

> ---

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