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Magnetos, Ignition Coils and Spark Plugs Discussion about magnetos, buzz coils, spark plugs, ignitors and low tension coils.

Magnetos, Ignition Coils and Spark Plugs

Ronaldson and Tippett Type N Magneto Coupling and Timing


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  #11  
Old 01-11-2019, 08:27:01 PM
cobbadog cobbadog is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Very nice work there. Looks too good to be hidden behind the maggy! How are you going on the search for the timing/spark marks?
On Flo the farm pumper the mark was buried under many coats of paint on the flywheel so that is why I got a good light and held it on every possible angle to find the mark. At that stage I did not want to remove any paint but that has changed now.

If you are able to find TDC with both valves closed, Scotty mentioned the mark is at the top of the flywheel and on the block at the same place. Set your points to be just opening then lock your drve connection in place. I don't know how far BTDC the spark should be but Scotty has been down this road with his ones so he can advise. He is not at home at the moment and I think he is going back tomorrow and he will bring you more helpful tips,
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  #12  
Old 01-11-2019, 09:14:18 PM
eddie bedwell eddie bedwell is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi David,
great job so far.
Hope I can post a page from the RB&T N Type Engine Book.
Copies likely available thru Plough Book sales near Geelong Victoria.

Many people get confused and set the tappets to 0.016" as the book says the clearance should never be less than this value.
The book actually says to adjust the tappet clearance to adjust the valve timing as outlined in the text.
There should be a TOP stamping on the periphery of the flywheel that aligns with a saw cut at the corner of the top surface of the cylinder block, directly above the crankshaft to indicate TDC or that the piston is at its highest point of travel.

The Exhaust Valve should close on TDC, BUT, if the line marked TOP on the flywheel periphery is within 1/2" either side of the saw cut on the crankcase this will be satisfactory.

The Inlet Valve should commence to open a 1/2" travel of the periphery of the flywheel in a forward direction after the exhaust valve closes.
It goes into a lot of confused procedure that basically means the inlet valve opens 1/2" of flywheel periphery travel before the exhaust valve closes---normal valve overlap seen in valve timing of most 4 stroke engines employing the Otto Cycle of valve timing.

As said the TOP mark and the saw cut are likely filled with rust and/or paint but with the piston on TDC the marks will be close to where described.

Hope this confused explanation helps--the book is very hard to understand.

Cheers,
Eddie B.
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  #13  
Old 01-11-2019, 09:29:37 PM
eddie bedwell eddie bedwell is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi David,
should have added that there is the word "SPARK" and a saw cut line for the exact alignment to the cyl. block saw cut is also stamped on the periphery of the flywheel for setting your magneto timing with the Lucas SR1 magneto points set to 0.010"--0.012" and just opening.
The spark word/line should align with the same saw cut on the cyl. block.
The spark word/line should be about 3/4" before the TOP/line.
On my twin flywheel engine the markings are very deep and once the periphery is cleaned around the TDC area should be easily seen.
Cheers,
Eddie B.
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  #14  
Old 01-12-2019, 01:08:00 AM
Pollardd Pollardd is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi Eddie,
Thanks for the detailed reply. I do already have that manual and I agree with you about it being a bit confusing. A picture speaks a thousand words and they chose words I guess they had a different writing style in the 20ís and pictures werenít easy to add to a printed manual.
I have just had a detailed look at the fly wheel and removed all rust and paint from the outside diameter of the fly wheel. There are no marks to be found.
I removed the paint and crud from the top of the crank case. I can easily see the original machining marks but nothing else. Looking at the block immediately where it meets the crank case no marks there either.
Moving forward I estimated the point on the crank case directly above the crank shaft and put a texta mark. I reckon Iím within a few mm.
I then removed the cover from the crank case and set up a scribe block to just touch the top of the bearing as it passes the top of the stroke.
With the scribe block touching I used a square from the crank case mark I put a mark on the fly wheel.
Now you say the spark mark if 3/4Ē Before TDC. Iím assuming the spark mark is to the right of TDC when standing in front of the fly wheel in the tanking position. That is ahead of TDC so the spark is triggered just before the maximum compression is reached or do I have that the wrong way around.

I havenít had the head off yet to watch when the valves open and close.
I figure I should only break one thing at a time

David
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Old 01-12-2019, 01:57:21 AM
eddie bedwell eddie bedwell is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi David,
SORRY my goof, as I described the SPARK line position on my engine with larger Diameter flywheels than your engine, so yours with smaller flywheels maybe around 1/2" to 5/8" from the TDC mark.

Just a thought you may find some marks on the sides of the flywheel rims as surely there should be some on it unless perchance it has a replacement flywheel which may not be marked.

You are on the right track.
I suggest you err on the side of being slightly retarded in mag. timing to begin with. If you find the engine tends to overheat quickly you can advance up a bit--if you go too far it will kick back when you try to crank it, then you will know to retard the timing a bit.
To get you started I guess an ignition timing to start with would be around 15--16 Deg BTDC and then experiment from there.

To save removing the cyl. head you can measure the circumference of the flywheel, divide that by 360 to give you inches per degree on the circumference and then work back from your TDC mark.

Hopefully some one else with a small flywheel engine can help out with some pics and/or dimensions.

Good luck with it as they are a sweet running robust engine.

Regards,
Eddie B.
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Old 01-12-2019, 02:55:24 AM
Pollardd Pollardd is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi Eddie,
Firstly no need to say sorry 😀
That gives me a great place to start with the timing.
I tried to get the fly wheel off just to clean it up and see what the end of the crank shaft looked like and could not get it off. The shaft, key and fly wheel all look original. I did have look at the inside face and didnít see anything. Maybe a second look is needed.
Iím not sure if me TDC mark is doing to be within 1 or 2 degrees but I guess we will find out.
I havenít even started on the carby yet so it might be a while yet before I give it a proper crank.
David
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  #17  
Old 01-12-2019, 06:12:29 AM
eddie bedwell eddie bedwell is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi David,
now it has cooled down some I have measured my flywheel dia. at 13".
Space between TDC and the Mag. timing mark is 7/8" = 0.875'.

Dykes Automobile and Gasoline Encyclopedia tells me the circumference is 40.86" and 1 degree is 0.11" so my poor math and Dykes tells me that the ignition timing will be approximately 8 degrees BTDC.
So my 'if unknown timing" of around 15 to 16 Deg. is a bit advanced for this N Type Ronnie if my math and Dykes is correct.

Hope this helps.
Cheers,
Eddie B.
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Old 01-12-2019, 10:40:02 PM
eddie bedwell eddie bedwell is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi David,
just looking back at your pictures in post #1 and I wonder IF something I have encountered before on Caterpillar machines that had linkage alignment issues after someone assembled said linkage incorrectly.
They had inserted the shaft key into the bolt clamp slot instead of the correct keyway cut at say 90 Degrees to the clamping slot.
This would put your apparently missing timing marks out of phase by 90 Deg. or what ever the angle difference is between the two slots.
Just a silly thought.
Cheers,
Eddie B.
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Old 01-14-2019, 02:51:35 AM
Pollardd Pollardd is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi Eddie,
I went out and measured my fly wheel and it is 12"
It is a little hard to measure exactly as I don't have a giant pair of calipers and the spindle where the crank handle goes in sticks out a bit.

I did measure the circumference fairly accurately and it is 36 1/8"

If I type that circumference into an online conversion tool it comes out to 11.538".

Maybe I'm going to need to make a big pair of calipers
I'm sure I will be able to calculate 8 deg some how from what I have.
I have noticed little agle marks on the back of the magneto. I wonder if they are going to assist me somehow.

I probably should double check my circumference measurement as well.

Also
Looking at the key and the clamping arrangement I don't think anyone has jammed the flywheel on 90 deg out of position but a good thought.

David
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Old 01-14-2019, 09:45:04 PM
eddie bedwell eddie bedwell is offline
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Default Re: Ronaldson and Tippett Type N Magneto Coupling and Timing

Hi David,
I also do not have a big set of outside calipers--I simply used a piece of fencing wire and kept tweaking it until it fitted the flywheel rim with out expanding or being unduly loose. Should be near enough to work with.

Take your circumference dimension and divide it by 360 for the length representing each degree--multiply by 8 and you should be close.

By my poor math :-

12" dia should be 37.7" circum. (using calculator) divide by 360 = 0.105" /degree x 8 = 0.84" = approx. 27/32" I stand to be corrected.

Hope this helps.
Cheers,
Eddie B
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