Ignition Mystery, Who Knows

So many posts under the lack of good spark. For the sake of sanity lets talk of a 12 volt side distributor 8N, although other N's can be related to the topic.
It seems the well respected recommendation of the Napa internal resister coil (ic14sb) is the go to coil. And for points it is the Napa (ics749). All is good so far, but little is said about the condenser #.

When looking up car condensers applications there are dozens of different numbers, which leads me to believe they are [u:a19aac55c6]very vehicle specific[/u:a19aac55c6], based on voltage/amperage and coil used.
So given the objection of the condenser to keep the points from arching and burning along with helping the collapse of the primary windings in the coil.
I would think the capacity and selection of the condenser to be very important, and given the large number of posts about burnt points, poor spark and hard starting problems very relevant.

So for those in the know, what number condenser do you come up with for the 12 volt conversion and what do you base that selection on? Also, have you had long term success with that selection?

Thanks Bill

" I would think the capacity and selection of the condenser to be very important,"

It's not.

At some point in my life, I could explain in boring detail WHY, buy all I've retained from that knowledge is 6v or 12v input does not matter.

JMOR can tell us though!
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I think that the capacitance is would probably not make a difference between 6 and 12 volts because the spark is basically the same in both systems, and when the coil secondary field collapses, the induced voltage spike in primary across points is the same and conducted across condenser rather than arcing across points. I could be wrong but think that's the idea.

It is the primary field that collapses to produce the voltage in the secondary.

(quoted from post at 12:05:51 02/17/21) It is the primary field that collapses to produce the voltage in the secondary.

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Physics 101 - Electricity and Magnetism

Current flow through the primary windings induces a magnetic field in the secondary windings. When the points open the current flow stops and the secondary field collapses producing a high voltage condition in the open secondary circuit. If that voltage is high enough it jumps the air gap (arcs) at the spark plug. That arc is what fires the fuel charge.

TOH

I am still wondering if there is no difference as to what condenser you use, why do we have so many different manufactured condensers, specified for different applications.

I understand there are some outside physical differences, but that does not explain why there are all the different internal capacities manufactured.

(quoted from post at 12:05:51 02/17/21) It is the primary field that collapses to produce the voltage in the secondary.

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The semantics being used here are a bit imprecise so perhaps a picture of coil construction would help.



The primary and secondary windings are both wound around the iron core and are overlayed with the primary wound around the secondary windings. When the points are closed and current flows through teh primary windings a magnetic field (there is only one) is induced in the iron core and surrounds both windings. When the current flow in the primary stops that single magnetic field collapses and as the lines of flux in the collapsing field cut across the windings it induces an EMF in both windings. The secondary section has many more windings than the primary and the induced EMF in that winding is much higher. ( Michael Faraday - 1791-1869). The secondary circuit is open at the spark plug gap and the induced EMF jumps the air gap to ground and fires the fuel charge. The smaller (reverse) EMF induced in the primary windings which are also now open at the points is dissipated through the condenser.

TOH

(quoted from post at 11:50:09 02/17/21) I am still wondering if there is no difference as to what condenser you use, why do we have so many different manufactured condensers, specified for different applications.

I understand there are some outside physical differences, but that does not explain why there are all the different internal capacities manufactured.

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Do you ever see any points and condensers for just 6 volts or just 12 volts? I don't. I am running one 8n with 12 volt mod with same points and condenser as when 6 volts. Did change the coil tho!

I agree with R. Geiger, I converted my NAA to 12 volts with a 12 volt coil and I'm also using the same condenser. I don't know, but perhaps a six or 8 cylinder engine would need a larger condenser so it wouldn't overheat?

I am trying not to argue but yes, I do see different part numbers for condensers for different vehicles both 6 and 12. That is the point, thus the question can you have a miss matched condenser which will maybe cause problems for you down the road?
Maybe a mute point, but maybe not?

Hate to see the look on the part mans face when you say, "give me a condenser, I don't care which one".

(quoted from post at 11:56:57 02/17/21)
I am trying not to argue but yes, I do see different part numbers for condensers for different vehicles both 6 and 12. That is the point, thus the question can you have a miss matched condenser which will maybe cause problems for you down the road?
Maybe a mute point, but maybe not?

Hate to see the look on the part mans face when you say, "give me a condenser, I don't care which one".

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About ANY automotive shop manual from the breaker point era had a "general service section" that gave helpful details on topics that applied to most makes and models, including how to "read points" to determine if the associated condenser was properly sized.

Since that is such a lost art and I don't have any of my old MOTOR or Chilton manuals at hand I looked on the 'net and was surprised how hard it is to find that info,

Here's ONE example of how pitting/metal transfer occurs if the capacitance is to large or too small for a given coil, look at the POLARITY of the contacts, (rather than the "breaker arm" and "contact bracket designations) as that would be the opposite between (+) ground and (-) ground.

First diagram was for a (-) ground system, this is for a (+) ground system.

Wore Out, that's good stuff. I still have a couple of ole Motors Manuals plus a Chilton's for Jeep pick-ups,Cherokees etc. for the late 60's and early '70s out in the garage. I'll have see it they have that in there.

Thanks TOH, I was attempting to convey the same idea but your description of whats going on with a condenser is much better

I have a side-mount 12V (converted) system on my 1951 8N. Electronic ignition - no points or condenser to worry about. Other than having to replace a failed coil (don't know the history of it or if it is original) the tractor starts in 9*F weather easily. Good spark. Pertronix kit. And, OT - I use 20W50 Synthetic oil in it - 200RPM cranking at 9*F, 20 PSI. zuhnc

(quoted from post at 16:02:22 02/17/21) Wore Out, that's good stuff. I still have a couple of ole Motors Manuals plus a Chilton's for Jeep pick-ups,Cherokees etc. for the late 60's and early '70s out in the garage. I'll have see it they have that in there.

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Jim, please post back with whatever info you find looking at your old manuals.

It seems to me that what once was common knowledge as to keeping ignition systems working and the details that went with that has been largely lost to the dustbin of history over the progression of time.

(quoted from post at 00:13:46 02/18/21)

(quoted from post at 16:02:22 02/17/21) Wore Out, that's good stuff. I still have a couple of ole Motors Manuals plus a Chilton's for Jeep pick-ups,Cherokees etc. for the late 60's and early '70s out in the garage. I'll have see it they have that in there.

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Jim, please post back with whatever info you find looking at your old manuals.

It seems to me that what once was common knowledge as to keeping ignition systems working and the details that went with that has been largely lost to the dustbin of history over the progression of time.

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954 Motors & looks same in 1958 edition. As an aside, I have never measured such condensers outside 0.2 to 0.3 microFarads. I did find one once where someone had used the noise suppression condenser, often found on generators, &bit actually seemed to run fine even though about 300 times too large at 55.0 microFarads

FORD 8N Angle (Side) Mount Distributor points are Standard Ignition/Blue Streak p/n FD-8081. Firing order on all FORDS is 1,2,4,3 but CCW up to the 8N. The NAA and after is CW. Many put distributor failings on a bad condenser. Most of us do not have the correct, and expensive machine to test a capacitor. In all my years of rebuilding FORD distributors, I've never had a 'bad' one. I would rebuild distributors and maybe put a new condenser in just because it was included in the kit. I have a coffee can full of new and used parts. There used to be condenser testing machines. Remember when you went to the local drug store and right inside the door was a tube testing machine? Like that. What's a tube? Before Solid State was the norm, electrical systems used vacuum tubes -even old vintage car radios. As I say often, incorrect/mucked up wiring is 99.98% of all electrical issues. Incorrect point setting (.025" +/- .001") and timing are usual culprits. The 8N Side Mount timing is set at 4 BTDC. Get the ESSENTIAL MANUALS for tune-up info and setting timing. Use the parts that come in the tune-up kit. You don't need to seek any car parts.

FORD 8N ANGLE MOUNT DISTRIBUTOR:

FORD 8N (AFTER S/N 263843), NAA, 600, & 800 TIMING:
CORRECT FORD 8N ELECTRICAL SYSTEMS - 6V & 12V:


*PICTOGRAM courtesy of JMOR




FORD 8N TRACTOR ESSENTIAL OWNER/OPERATOR/PARTS/SERVICE MANUALS:



Tim Daley(MI)

(quoted from post at 12:50:09 02/17/21) I am still wondering if there is no difference as to what condenser you use, why do we have so many different manufactured condensers, specified for different applications.

I understand there are some outside physical differences, but that does not explain why there are all the different internal capacities manufactured.

Click to expand...

Some interesting reading on the subject .

https://www.smokstak.com/forum/thre...at makes it work in the ignition application.

Looks like I want to buy Bosch from now on ?

http://www.nonlintec.com/sprite/cap_failure/