Cold WD will not start.

BruceNWMN

New User
the carb. On our Wd was rebuilt and replaced. Starts and runs great when engine is warm. When the engine is cold the only way to start it is to have the throttle open a little also use the choke and keep turning the engine, it will fire but wouldn't run. After numerous times. it will start but you have open the throttle slow to keep it running. My question is when the carb was off can the governor get out of adjustment or something?
 
Gov will not cause a hard start problem.
I would start by checking your spark it maybe weak which will cause hard start problems or your plugs are bad.
You need a good blue/white spark that jumps a 1/4 inch gap or more at the center cap wire and at the 4 plug wires.
Take a look at the plugs also and make sure they are a brown sort of color. If not and they are black they are likely to be fouled. Now day I use NGK 3112 plugs in all my machines since the other brands have gone down hill
If all that is good pull the carb drain plug and make sure you have a good steady flow of gas that will fill a pint jar in 3 minutes or less. Post back what you find
 
I totally relate as my WD is the same. Good engine, no smoke, no oil consumption to speak of, good compression, new ignition, new distributor cap, new plugs, new coil, good
spark, good gas, good flow through the carb, now on the 2nd carb - gone through and still will not start cold. It runs perfect when it runs and like yours starts perfect when
warm. In the heat of summer it starts good unless it has sat untouched for a few weeks and it's a cooler kind of a day. When the tractor is home I put the electric heat gun under
the carb long enough to make it luke warm and I get instant start and it runs perfect immediately. I'm soon going to take the head off and give it some TLC but this has been a
mystery for many years. I have several other tractors with the same engine and they're not like this.
 
Have you checked to see if choke is working right? We had several neighbors that had WD45s and if I remember right they were cold blooded. Did you ever think of putting a block heater on it? That would warm block and head. It would start right off the bat with the firing chambers being warm.
 
coil wired backward, venturie (sp) missing or upside down after rebuild. Have fixed starting problems from both problems over the
years.
 
Remove the air cleaner to carb hose and pull the choke clear "on". Visually make absolutely sure the spring loaded flapper is still on the choke plate. They sometimes lose the spring or the whole flapper and if missing, the choke is pretty much ineffective. When I was a kid, I have many fond Winter time memories of our never-fail-to-start WD-45 dragging around our 53 WD with the loader that usually failed to start when the weather was cold. I question the Marvel-Schebler carb on the WD as maybe not being the greatest for cold-weather starting??? How could the WD-45 with six volts always start, even when the battery could hardly turn it over, and that WD almost surely wouldn't start under the same conditions???
 
Misconception that a coil wired backwards will cause problems. Ya the spark maybe jumping backward but it will be very close to the same voltage and jump the same gap and still be a good blue/white in color. It that wasn't true all the old square coil N series fords would not run well when switched to 12 volts since there is no way to switch the coil polarity on them
 
Years ago we as in agri class experimented with this issue. Friend had an IH H that had to be pulled each cold morning. Class did coil pos to neg proper switch on cold tractor after setting out over weekend. It fired up on starter and owner reported that all winter it started with out being pulled. Coincidence, possible did not do double blind test (what ever that is), all I can say is nothing else was done to tractor. It was left at owners place same open shed for all test.
 
Been my experience that if the coil polarity was reversed, the life of the ignition points was drastically shortened.
 
Ah but when the wires where switched that in turn cleans up connections and very like it was a simple corroded connection so when you took the connection off and put them back on you have a better connection and IT DID NOT have to do with which wire was + or -
 
That to is a myth and as long as you have the correct coil or the correct ballast resister in place the point do not care which way current flows. Just like a light bulb does not care which side of it goes to ground but it sure does care that the voltage is correct.
 
Just as a public service to clear up some INCORRECT information and mistakes and misconceptions below:

COIL POLARITY DOES INDEED MATTER AND MAKES A DIFFERENCE

Does anyone really believe coil manufacturers go to the trouble and time and expense of labeling coils with + and -
terminals IF IT MADE NO DIFFERENCE HOW THEY WERE TO BE CONNECTED ???????????????

If it made no difference why have those + and - labels on them?????????????

Why have labels + and - but just have no label at all if it didn't matter how they are wired ??????


Without going over the heads of Billy Bob and Bubba, I will try to explain in simple terms the reasons I believe a coil is labeled + and - and why it DOES MAKE A DIFFERENCE AND WHY THEY BOTHER TO LABEL THEM + and -

Its easier to emit an electron from a hotter to a relatively cooler surface THATS WHY VACUUM TUBES USED A HEATER UNDER THE NEGATIVE CATHODE from where electrons were emitted up to the much cooler Positive Anode Plate. No reason for all the expense and construction and energy used to heat the Cathode if it didn't make any difference now is there???????????

Similar in a spark plug the ground strap is MUCH cooler then the hotter electrode tip exposed out there in the combustion chamber. On those its much easier to emit electrons from the hotter tip to the much cooler ground strap. If a coil is wired at the correct polarity as designed for and labeled by the design engineers, its also easier for the electrons to jump SAME AS IN A VACUUM TUBE WITH HEATER UNDER THE CATHODE. If its wired bass ackwards the plug still fires and indeed yes still has a spark BUT THERES LESS SPARK ENERGY (Amps x Volts X Time),,,,,,,,,,,The system is less efficient,,,,,,,,,,,And the coil runs a bit hotter as it has to work harder and climb to a higher voltage before its energy is released and dissipated. My nuclear physicist friend made a study of the firing voltage of a plug when the coil was wired correct versus if it was wired incorrect polarity, and the coil had to raise several thousand volts higher in order to fire the plug at the wrong polarity then if correct BECAUSE SAME AS IN A TUBE, ITS EASIER TO EMIT ELECTRONS FROM A HOTTER TO A COOLER SURFACE

IN ADDITION I was a farmer and used tractor dealer for yearssssssss and therefore owned and worked on more tractors then any 10 other typical farmers and have nearly 50 years of experience in tractors and old cars and electronics. I SAW AND LEARNED FROM EXPERIENCE THE EXACT SAME THING THAT COIL POLARITY MAKES A DIFFERENCE EVEN WITHOUT ANY ENGINEERING REASONS WHY.

Soooooooooooo if anyone can explain the theory it makes NO difference how a coil is wired and why the coil makers bother to place + and - labels if it doesn't matter, Im all ears, but it has to make sound engineering sense not old wife tales and urban legends lol Im never to old to learn so please explain to me why it don't matter how they are wired!!!!!!!!!!! And if so, why do the coil makers bother with those + and - labels in the first place

MY ADVICE WIRE A COIL AS ITS LABELED NOTTTTTTTTTTTTTTTT WHAT YOUR BROTHER IN LAW OR BILLY BOB OR BUBBA SAYS

However, its a free country and yall are free to wire them as you please regardless if its right or wrong

HOWEVER DONT BELIEVE ME, STUDY AND RESEARCH IT YOURSELF and listen to experts, NOT me or Billy Bob or your know it all brother in law lol See if you can find why a coil maker bothers to label the terminals + and -. I MAY BE WRONG AS RAIN (wont be first or last time lol) AND IM WILLING TO LEARN SO HELP ME OUT HERE, BUT IM PRETTY SURE COIL POLARITY DOES INDEED MATTER...

John T BSEE, JD Electrical Engineer retired Yall keep safe and heres an early Merry CHRISTmas I hope this helps
 
Just as a public service to clear up some INCORRECT (in my opinion) information and mistakes and misconceptions below:

COIL POLARITY DOES INDEED MATTER AND MAKES A DIFFERENCE

Does anyone really believe coil manufacturers go to the trouble and time and expense of labeling coils with + and -
terminals IF IT MADE NO DIFFERENCE HOW THEY WERE TO BE CONNECTED ???????????????

If it made no difference why have those + and - labels on them?????????????

Why have labels + and - but just have no label at all if it didn't matter how they are wired ??????


Without going over the heads of Billy Bob and Bubba, I will try to explain in simple terms the reasons I believe a coil is labeled + and - and why it DOES MAKE A DIFFERENCE AND WHY THEY BOTHER TO LABEL THEM + and -

Its easier to emit an electron from a hotter to a relatively cooler surface THATS WHY VACUUM TUBES USED A HEATER UNDER THE NEGATIVE CATHODE from where electrons were emitted up to the much cooler Positive Anode Plate. No reason for all the expense and construction and energy used to heat the Cathode if it didn't make any difference now is there???????????

Similar in a spark plug the ground strap is MUCH cooler then the hotter electrode tip exposed out there in the combustion chamber. On those its much easier to emit electrons from the hotter tip to the much cooler ground strap. If a coil is wired at the correct polarity as designed for and labeled by the design engineers, its also easier for the electrons to jump SAME AS IN A VACUUM TUBE WITH HEATER UNDER THE CATHODE. If its wired bass ackwards the plug still fires and indeed yes still has a spark BUT THERES LESS SPARK ENERGY (Amps x Volts X Time),,,,,,,,,,,The system is less efficient,,,,,,,,,,,And the coil runs a bit hotter as it has to work harder and climb to a higher voltage before its energy is released and dissipated. My nuclear physicist friend made a study of the firing voltage of a plug when the coil was wired correct versus if it was wired incorrect polarity, and the coil had to raise several thousand volts higher in order to fire the plug at the wrong polarity then if correct BECAUSE SAME AS IN A TUBE, ITS EASIER TO EMIT ELECTRONS FROM A HOTTER TO A COOLER SURFACE

IN ADDITION I was a farmer and used tractor dealer for yearssssssss and therefore owned and worked on more tractors then any 10 other typical farmers and have nearly 50 years of experience in tractors and old cars and electronics. I SAW AND LEARNED FROM EXPERIENCE THE EXACT SAME THING THAT COIL POLARITY MAKES A DIFFERENCE EVEN WITHOUT ANY ENGINEERING REASONS WHY.

Soooooooooooo if anyone can explain the theory it makes NO difference how a coil is wired and why the coil makers bother to place + and - labels if it doesn't matter, Im all ears, but it has to make sound engineering sense not old wife tales and urban legends lol Im never to old to learn so please explain to me why it don't matter how they are wired!!!!!!!!!!! And if so, why do the coil makers bother with those + and - labels in the first place

MY ADVICE WIRE A COIL AS ITS LABELED NOTTTTTTTTTTTTTTTT WHAT YOUR BROTHER IN LAW OR BILLY BOB OR BUBBA SAYS

However, its a free country and yall are free to wire them as you please regardless if its right or wrong

HOWEVER DONT BELIEVE ME, STUDY AND RESEARCH IT YOURSELF and listen to experts, NOT me or Billy Bob or your know it all brother in law lol See if you can find why a coil maker bothers to label the terminals + and -. I MAY BE WRONG AS RAIN (wont be first or last time lol) AND IM WILLING TO LEARN SO HELP ME OUT HERE, BUT IM PRETTY SURE COIL POLARITY DOES INDEED MATTER...

John T BSEE, JD Electrical Engineer retired Yall keep safe and heres an early Merry CHRISTmas I hope this helps
 


I have had some tractors that started hard when cold. rebuilt carburetor, new points, plugs, wires and cap, still did not solve the problem, reset the ignition timing cured the hard starting problem.
 
Not to start an argument here but in a 4 cylinder magneto, the polarity switches back & forth as the rotor turns. So the coil is firing both ways & engine is running on all 4's.
 
Big question is, how was it BEFORE you had carburetor worked on?

Weak spark can make an engine need more fuel to light mixture, Old usually professes to verify solid blue spark at each spark plug first, he is right.

My Farmall wants a couple of cranks of full choke, then choke off.
 
Exactly that's one disadvantage of a Magneto, since the rotor has BOTH a North and South magnetic polarity. Fortunately that's not true in a battery powered coil ignition

John T
 
Apparently, you didn't have a problem before the carb was worked on?
Try opening the main jet a quarter turn or so.
Also, is the float set correctly?
Is there a good tight fit between the carb and the manifold?

I have to open the main jet on my WD in cold weather to keep it from "stumbling" on acceleration.

I'm an old guy so I've been driving nearly 60 years.
In my experience, every engine seems to have a "life of its own" when it comes to cold starting; some like a lot of choke, some little and some like the throttle open and some don't.

My WD, which I converted to 12 volts, starts even when it's zero.
It is a little different from my WD-45 which requires some choke to get it to fire.
With the WD, I must leave the throttle closed and don't touch the choke when first turning over the engine. It will fire right up!
Then....immediately, I must "feather" the choke while gradually opening the throttle. otherwise it will become seriously flooded and then I have a heckuva time getting it started.
 
John T will even say that the spark is very close to the same and not enough to matter. As for how long you have worked on something that has little to do with it either. If that come into play then the fact I was a Navy Electronics Teck. should tell you I know I am right and spark does not care if it is + or - as for the coils. Now things like transistors care which is + and - as does many electronic circuits and that is why if you hook up a - ground alternator + ground you will let the smoke out before you can pull the battery cable back off
 
You can also stop the stumbling if you make a jacket around muffler and a tube to the top of air intake stack and suck warm air from around the hot muffler. Once it starts pulling warm air it will run like it does in the summer and it can be 20 below outside. It can be 20 below zero outside and air cleaner and carb will be warm and you won't have any icing problems with carb. or intake manifold.
 
To further clear up what I believe to be INCORRECT information posted below, here's what one person in quotes has posted and my engineers response. My analysis is based on my electrical engineering education (BSEE Purdue University), and over 40 years of experience in electronics and being an old tractor dealer having to repair the darn old things lol.

A person is entitled to their own opinions BUT NOT THEIR OWN FACTS...


1) ?That to is a myth and as long as you have the correct coil or the correct ballast resister in place the point do not care which way current flows?

CORRECTION no points don't care what direction current flows HOWEVER the coil sure does, see the reasons why below in my post

2) ?Misconception that a coil wired backwards will cause problems.?

THAT IS COMPLETELY WRONG see the reasons below

3) ?Ya the spark maybe jumping backward but it will be very close to the same voltage?

THAT IS COMPLETELY WRONG If wired at the wrong polarity the voltage must rise perhaps a thousand volts or even a few thousand volts higher in order to arc jump current across the gap. A few years back a Nuclear Physicist wired the same plug to the same coil and measured voltages with correct versus incorrect polarity AND IT TOOK ALMOST FOUR THOUSAND VOLTS HIGHER VOLTAGE if the coil was wired wrong.


Here is the re posted engineering analysis I posted below. DO NOT believe me, research scientific literature from competent trained professionals and engineers and technicians and then form your own opinion of whether or not a coil should be wired at the correct polarity or not and the bad effects if its not.


A COPY OF MY POST BELOW

COIL POLARITY DOES INDEED MATTER AND MAKES A DIFFERENCE

Does anyone really believe coil manufacturers go to the trouble and time and expense of labeling coils with + and - terminals IF IT MADE NO DIFFERENCE HOW THEY WERE TO BE CONNECTED ???????????????

If it made no difference why have those + and - labels on them?????????????

Why have labels + and - but just have no label at all if it didn't matter how they are wired ??????


Without going over the heads of Billy Bob and Bubba, I will try to explain in simple terms the reasons I believe a coil is labeled + and - and why it DOES MAKE A DIFFERENCE AND WHY THEY BOTHER TO LABEL THEM + and -

Its easier to emit an electron from a hotter to a relatively cooler surface THATS WHY VACUUM TUBES USED A HEATER UNDER THE NEGATIVE CATHODE from where electrons were emitted up to the much cooler Positive Anode Plate. No reason for all the expense and construction and energy used to heat the Cathode if it didn't make any difference now is there???????????
Similar in a spark plug the ground strap is MUCH cooler then the hotter electrode tip exposed out there in the combustion chamber. On those its much easier to emit electrons from the hotter tip to the much cooler ground strap. If a coil is wired at the correct polarity as designed for and labeled by the design engineers, its also easier for the electrons to jump SAME AS IN A VACUUM TUBE WITH HEATER UNDER THE CATHODE. If its wired bass ackwards the plug still fires and indeed yes still has a spark BUT THERES LESS SPARK ENERGY (Amps x Volts X Time),,,,,,,,,,,The system is less efficient,,,,,,,,,,,And the coil runs a bit hotter as it has to work harder and climb to a higher voltage before its energy is released and dissipated. My nuclear physicist friend made a study of the firing voltage of a plug when the coil was wired correct versus if it was wired incorrect polarity, and the coil had to raise several thousand volts higher in order to fire the plug at the wrong polarity then if correct BECAUSE SAME AS IN A TUBE, ITS EASIER TO EMIT ELECTRONS FROM A HOTTER TO A COOLER SURFACE
IN ADDITION I was a farmer and used tractor dealer for yearssssssss and therefore owned and worked on more tractors then any 10 other typical farmers and have nearly 50 years of experience in tractors and old cars and electronics. I SAW AND LEARNED FROM EXPERIENCE THE EXACT SAME THING THAT COIL POLARITY MAKES A DIFFERENCE EVEN WITHOUT ANY ENGINEERING REASONS WHY.

Soooooooooooo if anyone can explain the theory it makes NO difference how a coil is wired and why the coil makers bother to place + and - labels if it doesn't matter, Im all ears, but it has to make sound engineering sense not old wife tales and urban legends lol Im never to old to learn so please explain to me why it don't matter how they are wired!!!!!!!!!!! And if so, why do the coil makers bother with those + and - labels in the first place

MY ADVICE WIRE A COIL AS ITS LABELED NOTTTTTTTTTTTTTTTT WHAT YOUR BROTHER IN LAW OR BILLY BOB OR BUBBA SAYS
However, its a free country and yall are free to wire them as you please regardless if its right or wrong. HOWEVER DONT BELIEVE ME, STUDY AND RESEARCH IT YOURSELF and listen to experts, NOT me or Billy Bob or your know it all brother in law lol See if you can find why a coil maker bothers to label the terminals + and -.

I MAY BE WRONG AS RAIN (wont be first or last time lol) AND IM WILLING TO LEARN SO HELP ME OUT HERE, BUT IM PRETTY SURE COIL POLARITY DOES INDEED MATTER...

John T BSEE, JD Electrical Engineer retired Yall keep safe and heres an early Merry CHRISTmas I hope this helps
 

It ALL comes down to enough energy at the Sparkplugs...

If ya have FUEL, all it needs is Spark ( at the correct time) to make it FIRE...

Ron..
 
Oh by the way if a mag does not work well then why is it there are thousands of aircraft in the air with mags on them and they have been that way for decades??
 
But Ah, Who said a Mag don't work well?????????? I'm just agreeing with Teddy that on many old tractor mags the rotor has a North and South magnet end so every other spark has the opposite polarity HOWEVER a mag does not necessarily have to be used that way, the North ORRRRRRRR South end could provide the needed energy, an old tractor mag likely isnt the quality and design of an aircraft mag now is it.

Hope this helps and answers your question

John T
 

John, I agree the voltage to jump the gap will increase if the polarity is reversed. You have explained, very well, the reason for this increase. You also state the spark energy (volts x amps x time) will decrease, could you explain why the spark energy decreases? Why will the amps and/or time decrease? This is counter intuitive to me... I always understood increasing the plug gap (also increases voltage) would increase the spark energy. Did your friend also measure the spark energy as well as the voltage?

Thank you, Ken
 
John: Do you really think there is much of a temperature difference between the ground strap and center electrode when they are .025 apart?????????????
 
SURE IS the porcelain/ceramic coated electrode tip is hanging out there in the combustion chamber with all the explosions and hot explosive gasses are, while the ground strap has the huge thermal conducting heat sink mass to cool it wayyyyyyyyyyy down and the radiator is keeping engine coolant temp (which transfers heat from block to radiator to the air) down to say 180 degrees. Im sure you already had to know all that Teddy? A mechanical or thermodynamics engineer or engine designer can tell you the typical combustion chamber electrode tip versus ground strap temperatures, I don't know them, but do know the difference is HUGEEEEEEEEEEE

A also now its easier to emit electrons from a hotter to a cooler surface like why a heater in a vacuum tube is placed under the Cathode to emit electrons up to the cooler anode WELL DUH

John T
 
SURE IS the porcelain/ceramic coated electrode tip is hanging out there in the combustion chamber with all the explosions and hot explosive gasses are, while the ground strap has the huge thermal conducting heat sink mass to cool it wayyyyyyyyyyy down and the radiator is keeping engine coolant temp (which transfers heat from block to radiator to the air) down to say 180 degrees. Im sure you already had to know all that Teddy? A mechanical or thermodynamics engineer or engine designer can tell you the typical combustion chamber electrode tip versus ground strap temperatures, I don't know them, but do know the difference is HUGEEEEEEEEEEE

A also now its easier to emit electrons from a hotter to a cooler surface like why a heater in a vacuum tube is placed under the Cathode to emit electrons up to the cooler anode WELL DUH

John T
 
Hi Ken, great question. Here's my theory why spark energy would be less. Since reverse coil polarity makes it necessary for the coil to raise to a higher voltage which takes a longer time (it ramps up you know, its NOT suddenly 10,000 volts) that means the temperature of the coil has to rises. The ignition process does NOT create or destroy energy, it only changes in form. If heat energy is increased and the coil ignition process cant create or destroy energy, that leaves less V x I x Time spark gap energy to my way of energy conservation thinking.

When my deceased Nuclear Physicist friend Duane Larson conducted his experiments (and he was a perfectionist and a real detail oriented stickler) he found if the coil polarity was reversed the necessary firing voltage before the plug fired was like 4000 volts higher BUT NO HE DIDNT MEASURE SPARK GAP ENERGY DISSIPATION

When the coil has conducted current and stored x amount of energy in the form of a magnetic field but then the points open there is only x jules of stored energy available for dissipation and its dissipated as Volts X Amps x Time across the spark plug gap arc discharge PLUS heat energy. If it takes more time before the voltage has to ramp up higher, to me the coil temp has to rise, and that wasted heat energy is NOT available for spark gap energy dissipation.

Hey Im NOT a Thermodynamics Engineer and thermo was one of my worst subjects lol SO NO WARRANTY

HOWEWVER I do know coil voltage must rise higher at reverse coil polarity,,,,,,,,,,,,For over a hundred years engineers and scientists designed coils to operate at the correct polarity (for reasons I explained),,,,,,,,,,,,,For over a hundred years car and truck and tractor makers wired coils at the correct polarity, so were they allllllllllll wrong and someone here now right??? Or it dont matter or makes no difference how a coil is wired???? I THINK NOT but yall choose to wire coils correct like auto makers and coil designers did for a hundred years, or wire them backwards.........

Thanks Ken GREAT QUESTION I cant guarantee my heat energy theory is right, but I do know its easier to emit electrons from a hotter (spark plugs ceramic/porcelain coated electrode tip in combustion chamber) to a cooler surface (ground strap cooled by huge heat dissipating thermal mass) AND THATS WHY COIL POLARITY IS IMPORTANT AND WHY DESIGNERS AND AUTO MAKERS DESIGNED AND WIRED THEM A CERTAIN WAY. To them it DID MAKE A DIFFERENCE
 
It is kinda deceiving, cause when you heat a plug with a propane torch, the ground strap gets red hot first. But then it is not cooled by the mass it is screwed into.
 
Ken, heres another alternate theory concerning the improved performance if a coil is wired correct NOT HEAT RELAYED LIKE I POSTED BELOW. Remember Im NOT a Thermodynamics Engineer but an Electrical so here goes.

When the points break open there is finite x jules of stored energy to dissipate, some in the form of heat, other as Volts x Amps X Time. If we consider ONLY electrical energy, since the voltage must rise higher if the coil is wired wrong that means either Amps or Time must decrease to dissipate the same energy.

We all know if you observe a spark that as you increase the gap distance the spark goes from a hot blue to a thin wimpy more yellow cooler spark. NOW if its more the heat energy that ignites the compressed fuel air mixture then what voltage is, the hotter blue spark at less voltage would better ignite the fuel then the cooler less current but higher voltage yellow spark.

MAYBE THATS MORE THE REASON WHY COILS PERFROM BEST IF WIRED CORRECT since if wired wrong the voltage must increase therefore the current and arcing heat is less???????????

Id say its an engineering fact its best if a coil is used as designed and the way auto and truck and tractor makers have wired them for years, BUT IS IT DUE TO COIL HEAT ENERGY DIFFERENCES OR IN THE TEMPERATURE OF THE SPARK?????????????

Seems to me its the sudden burst of HEAT ENERGY that ignites the fuel and not so much the voltage across the gap. Its the arc of extreme high heat current (Blue spark) through the gap that ignites the fuel and NOT voltage across the gap (more voltage less current = cooler yellow spark) Regardless, its best if the coil is wired at the correct polarity and it DOES MAKE A DIFFERENCE and why they are designed and labeled at a certain polarity and why car makers wire them that way NOT backwards............

Thanks Ken VERY FUN SPARKY CHAT

John T
 
I may be deceiving Teddy, but you know the engine block is cooler then what it is inside the combustion chamber and the block is one HUGE good thermal conductor and one HUGE mass of a heat sink. If you dont understand that I cant help you, sorry, but hey I get credit for trying now lol

take care, fun chatting with you, hope this helps

John T
 
I'm with Brian. I had a WD that would start at far colder temps than I cared to be out in. Had a 12v battery, 12v coil (wired correctly), and dist. Did need a little choke, but it would start down to well below zero just fine. Make sure your electrical parta are wired right (see heated discussion above) and make sure your carb is set right.
AaronSEIA
 
John T.
I have been following this thread with a fair amount of interest (amusement). I have also noted your many responses to electrical questions over the years and your standard troubleshooting procedure, and as I recall, you have done some instruction on magneto technology in the past.
So, this weekend, while down at the farm, I dug out my containers of old FMJ rotary magneto parts. I used parts from several to make one good one for my AC WD.
The one point of debate in this long thread that has puzzled me is the comment that the magento results in the spark travelling in reverse direction every second fire. I understand the two-pole principle that is mentioned. However, I always thought that there was some compensating electrical design feature that kept the spark at the points constant in direction and thus the collapse of the primary field and the orientation of the secondary impulse and spark constant in direction. Otherwise, two of four cylinders repeatedly fire with opposite polarity.
I have not seen an actual schematic of a four post rotary magneto to base my belief on, and my knowledge of electrical theory is probably too outdated to help me anyway.
I just wondered if it is actually true that two cylinders fire backwards through the spark plug. I wondered if the orientation of the coil or grounding of the point set acted as a half wave rectifier, so to speak, and kept all spark plugs firing similarly.
I do know that GM used the concept of waste spark in small car engines some 50 years later, in which the plugs actually fire backwards during the scavenging stroke, and some plugs do not respond well to the experience.
Obviously, this question will not help Bruce start his cold WD, so my apologies for hijacking his thread.
Thanks,
stu
 
Stu, I haven't messed with more then two pole (North and South) permanent magnet rotors, but I know on those theres a North and South pole same as any small magnets you may have seen as a kid or in a science project. When you pass a magnet past a coil of wire (like a rotating magnet inside a magneto armature) or the coil past the magnet, voltage is induced across the wire coil ends and its electrical polarity (+ or -) depends on the magnetic field polarity IF WHAT I RECALL FROM 40 YEATRS AGO IS CORRECT LOL NO WARRANY. The typical tractor mag (maybe aircraft are different) ONLY has one coil, so when a North then a South magnet passes its polarity is opposite each time. On the Wico C or X Mags (Model AP is gear reduction 1/2 speed, no wasted spark ) I'm most familiar with it fires at EACH magnet passing (North and South) therefore every other plug fires at opposite current flow directions. For that reason when the flow of electrons jumps from electrode tip to ground strap the firing voltage will be less then the opposite firing when its reverse polarity, but she still fires of course. My explanations below offer two possible reasons either due to wasted heat energy in the coil itself or that theres less arc temperature heat (yellow versus blue spark) for why its best to fire at the correct polarity and why coil design engineers as well as car and truck and tractor makers for 100 years always wired coils at the correct labeled polarity. I NEVER saw a car or truck or tractor (or even a lawn mower lol) from the factory with backwards reverse polarity coil wiring, as they for sure had a reason for design and bothering to label if it made absolutely NO difference or was a misconception or an old wives take lol

BUT YOUR QUESTION MAKES ME THINK In the Two Cylinder John Deere NON reduction drive gear mags like Wico C and X, there is as you note a wasted spark as it fires on BOTH the Power and Exhaust stoke TDC's. If the lower energy spark occurred on the exhaust TDC but higher energy on the power TDC, THAT WOULD SEEM THE BEST WAY TO OPERATE!!!!!!!!!!! I would have to look at timing to figure that out........

ALSO it would be possible due to drive system (like crank RPM versus cam RPM) and timing to maybe fire a plug on compression TDC USING ONLY ONE LIKE NORTH OR SOUTH MAGNET END SO POLARITY IS ALWAYS THE BEST?????????

To fully answer your question a person would have to research different brands and types of magnetos along with their drive and timing to see if they fire plugs on their compression power strokes?????????? I JUST DONT KNOW THAT

I basically just know that its easier and more efficient to arc electrons from a hotter (electrode tip encased in ceramic/porcelain out in combustion chamber) to a cooler (ground strap part of threads encased in MUCH cooler engine block) the same reason why vacuum tubes place a heater under the cathode where electrons are emitted up to the much cooler plate.

Soooooooooooo I can talk best about battery powered ignition coil correct designed and labeled + and - polarity then I can Magnetos and that would take a lot more study, sorry no answer for sure other then wasted sparks on exhaust TDC and/or RPM and timing may make it such that its only the correct polarity sparks that's used?????????????????????

Nuff said, yall done wore my old brain out lol Ive been wrong before so again NO FREAKING WARRANTY but until Im proven otherwise Im stickin with coil polarity does indeed make a difference and it DOES MATTER its NOT a myth, or else coil designers and car makers are all wrong the past 100 years?????????????????????

John T
 

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