A Comment on Condensors

[Guest Grumpy's Auto Shop]

There are two threads currently asking about a specific part working in a particular application.  I don't have an answer for either of these questions but thought I might offer some wisdom.

 

First off, a Condensor or Condenser is in fact a Capacitor.  Its function in a points ignition system is well described in many other places, so I will not repeat it here.

 

It is an electronical [stet] component, the specs of which are not very far from one another in any given points-fired ignition system.  What this means is that the condenser from your lawn mover will also work in your car, with only a few caveats.

 

From an electrical standpoint these caveats have mostly to do with voltage.  A 6v component in a 12v system WILL let the smoke out. (and the smoke is what makes electrical stuff work in the first place...)  A 12v cap simply won't care (as if caps cared in the first place).

 

In general terms Caps have never been made very precisely, rather, they operate over a range.  Bob Mackie will disagree but he never designed an ignition system.

 

It is a matter of fact than 'points, plugs, condenser, cap and rotor' are standard 'tune up' items.  But it is rare that ANY ignition fault was due to the Condenser.  They get replaced because the guy with the wrenches was already there and because the manual says to do it.  It makes sense because the part is relatively cheap.

 

However, this also has to do with fitment.  The Condenser has mostly no concern for its location.  It will function regardless.  (No!  You cant put it the trunk. But it doesn't have to be IN the Dizzy to still function correctly.)

 

The biggest mistake I see is that they are not grounded.  In DC circuits, Caps have to be grounded.  They just do.

I apologize for ranting.  My significant other in law just came to take me for dinner, so I have to press 'submit' instead of editing this post. I hope the info was useful.

[hchris]

Couldn't agree more,  too much hysteria devoted to condensors. If needs be carry a spare,; when necessary connect it to the primary wire from coil to distributor and body to good earth, if the problem still exists start looking elsewhere. 

[Guest BillP]

I've had condensers fail on two occasions. One on a '68 Biscayne standard six four door, former county-issue black sedan. I was with family in the Adirondacks, driving along smoothly and the engine quit. Changed condenser and back on the road. The other at the entrance gate of a car show with 356 Porsche; one minute idling, the next, nobody home. Changed condenser right there and went into the show. BTW, good point gap, all else in good order. 

 

I always carry a spare in the glove box.

[TerryB]

The function of the condenser is to soften the effects of the points opening the current flow in the coil.  By using a condenser, or capacitor as it's known in the electronics world, the energy the coil is producing is buffered at the points keeping the points from premature wear that we call burning or pitting.  When the condenser develops an internal electrical short to ground the action of the points no longer has an effect and there is no spark.  If the condenser goes open circuit, the engine will run but the points will not be able to withstand the constant coil energy bombardment and will eventually fail due to pitting or loss of contact material on the ends.

 

Terry

Edited September 19, 2016 by TerryB (see edit history)

[drwatson]

I use an ohm meter to say yes or no to a suspect condenser.  I watch meter needle move up as cap charges, then reverse leads and observe meter needle move rapidly in opp direction. (cap discharge)

If cap. shows a steady resistance reading it's likely a dud.

My "on the road" condenser failure was odd because my 4cyl Mercedes idled & ran but not above 1000 rpm; could only crawl along H-way at 15-20mph, Scrounging up a used condenser put things back to normal

on that road in Alabama.

[padgett]

Agree particularly for points it is just there to keep the points from burning and to reduce radio noise. For short periods can leave off of the points cars I know.

 

OTOH a good condenser is essential for my AC. Please distinguish which you are talking about.

 

 

[benjamin j]

15 hours ago, Grumpy's Auto Shop said:

There are two threads currently asking about a specific part working in a particular application.  I don't have an answer for either of these questions but thought I might offer some wisdom.

 

First off, a Condensor or Condenser is in fact a Capacitor.  Its function in a points ignition system is well described in many other places, so I will not repeat it here.

 

It is an electronical [stet] component, the specs of which are not very far from one another in any given points-fired ignition system.  What this means is that the condenser from your lawn mover will also work in your car, with only a few caveats.

 

From an electrical standpoint these caveats have mostly to do with voltage.  A 6v component in a 12v system WILL let the smoke out. (and the smoke is what makes electrical stuff work in the first place...)  A 12v cap simply won't care (as if caps cared in the first place).

 

In general terms Caps have never been made very precisely, rather, they operate over a range.  Bob Mackie will disagree but he never designed an ignition system.

 

It is a matter of fact than 'points, plugs, condenser, cap and rotor' are standard 'tune up' items.  But it is rare that ANY ignition fault was due to the Condenser.  They get replaced because the guy with the wrenches was already there and because the manual says to do it.  It makes sense because the part is relatively cheap.

 

However, this also has to do with fitment.  The Condenser has mostly no concern for its location.  It will function regardless.  (No!  You cant put it the trunk. But it doesn't have to be IN the Dizzy to still function correctly.)

 

The biggest mistake I see is that they are not grounded.  In DC circuits, Caps have to be grounded.  They just do.

I apologize for ranting.  My significant other in law just came to take me for dinner, so I have to press 'submit' instead of editing this post. I hope the info was useful.

In general terms Caps have never been made very precisely, rather, they operate over a range.  Bob Mackie will disagree but he never designed an ignition system.    I am sitting in an office full of electrical engineers none of them are named Bob and they would all disagree with this statement.

[mrspeedyt]

 i'm glad others have confirmed what I have thought in the past. specifically a 12 V condenser will suffice.  as long as it meets the physical characteristics. 

[cahartley]

I have experienced the effects of bad condensers.

Poor spark which leads to either popping and backfiring or no spark at all.

There is more to the function of a condenser than preventing arcing at the points.

When the points are closed the condenser is acting as a buffer as it stores energy.

When the points open the condenser discharges the stored energy through the coil primary which vastly increases the spark intensity.

That it also minimizes points arcing is only a happy side effect.

 

[jp928]

Reported recently in UK, a potato (or part thereof) was used to replace a dud condensor in a farmer's LR, got him back to work.

 

jp 26 Rover 9

[Friartuck]

Could I get some thoughts on locating a condenser not close to the points? This dual point DELCO distributor is in the front of the engine and the two coils are on the inside of the firewall, some 36 inches of wire away. The condensers are mounted below the point plate which make it a pain to replace. A quick fix in the past has been to hang generic condensers on the 6 volt coil wires outside of the distributor body which looks horrible. Any prediction on attaching the condenser on the coil end. How much does that 36 inch wire make on condenser performance on the points?

[hchris]

Shouldn't have any influence at all, as already stated its job is to simply absorb the current flow when the points close and resist points arcing when they open. So long as it has good electrical connection in the primary circuit it will do the job. 

[Willie Wurke]

Everyone who answered this post is misinformed

DC will not pass through a condenser; only AC will

I'll let a graduate EE explain ( hope we have one!)

It gets very exciting

[Willie Wurke]

14 hours ago, Friartuck said:

Could I get some thoughts on locating a condenser not close to the points? This dual point DELCO distributor is in the front of the engine and the two coils are on the inside of the firewall, some 36 inches of wire away. The condensers are mounted below the point plate which make it a pain to replace. A quick fix in the past has been to hang generic condensers on the 6 volt coil wires outside of the distributor body which looks horrible. Any prediction on attaching the condenser on the coil end. How much does that 36 inch wire make on condenser performance on the points?

 

[padgett]

Capacitors are often speced +/- 20% so are more of an electric spring than anything else. The ignition coil has so much more inductance (L) than an ignition capacitor has capacitance (C) that the caps effect is insignificant other than smoothing the point arc which also reduces radio interference. They are two conductor devices and like many to reduce cost the can makes the ground connection. Does not need to be ground, just different (see a RLC filter) levels.

 

Helps to know what "Eli the ice man" means.

 

BTW if the ignition wires are resistive, they can have a large effect on the capacitive effect on the points so mounting at a distance would be self-defeating.

 

ps ever look at an ignition trace on a 'scope ? Not exactly DC.

Edited September 21, 2016 by padgett (see edit history)

[Willie Wurke]

The length of the condenser lead affects its capacitance rating and results in pitted points. ( pic looks like a 1929 L Lincoln!)

[Larry Schramm]

36 inches of good wire including a good ground for the capacitor should not be a problem.  The key here is good electrical connections.

 

Now if you run the wire parallel to and next to the spark plug wires that is another issue and problem.

Edited September 21, 2016 by Larry Schramm (see edit history)

[Curti]

In that era many condensers were hung on the outside of the distributor but not with phillips screws. 

[padgett]

Interesting. Is that a dual point conversion ? Adjustments are completely different.

[Curti]

It is not a conversion, Auto-Lite IGH-4027  supercharged Auburn. Yes the adjustments are different. 

The six cylinder Auburns also had the condenser mounted externally.

[60FlatTop]

When the unit of measure is one millionth of a farad, + or - even 20% makes me smile. Put that in your condenser and smoke it.

 

If you find a burned set of points due to the condenser it probably didn't work from day one, just took that long for the points to burn.

Bernie

[Ivan Saxton]

Two sets of points on a 4 lobe cam was common practice for a lot of 8 cylinder cars in the late 20s-early 30s.  It would give a better dwell angle.  I have seen less frequently two sets of points with an 8 lobe cam; set so one set of points breaks the circuit to induce the High voltage spark, and the other re-connects the primary current; presumably on the assumption that will diminish arcing on the points.   I recall that the quality and sustainability of ignition capacitors was a bit marginal in the 1950s-60s.  It was always prudent to replace points and capacitor simultaneously if the points became pitted.  Later they would run forever if you remembered that the bakelite foot that rode the distributer cam could wear and reduce points gap and upset dwell angle.   I distinctly remember that  a forties Ford tow truck prang removal unit that was loaned to me to drag home a 1923 Cadillac with no body or front axle died on me in traffic.  It recovered when I substituted a spare from the glove box, or so I recall.  Sometimes an engine would run alright from cold, but mysteriously give up when the capacitor ran hot;  but it would start again  when the engine cooled.   Early magneto capacitors could be a problem.  On a lot of magnetos they were assembled into the armature after that was re-wound; so they had special geometry and were not very accessible for service, nor available as replacement in the 70s.  I was instructed by an older auto-electrician at Hamilton in Western District of Victoria.  Bert Fleming had a soft residual Canadian accent; and he was very experienced and had thorough technical understanding.  It was not really prudent to measure the capacitance or leakage on a capacitor tester; because it was not predictable whether the machine would destroy whatever life the old capacitor had left.   Bert told me that his family had a T Ford when he was a lad, and he mostly drove it because his father was hopeless.  It was not the best to drive to town wearing your own front gate.   He just could not grasp the options available in three pedals and the hand brake to slow down and stop.  Eventually, like Mark Twain's father he improved a bit with age.  He learned to stop on compression  by switching off the ignition.

Discharging a big capacitor can be quite shocking.  I have known of the odd case of vandalistic youth discharging one across one of our native huntsman spiders,  which are quite harmless, though they may look  a bit fearsome with their legspread of nearly 3 inches .  If you wonder why higher animals are very sensitive about conducting high voltages, you need only consider the structure of nerve cells and their means of carrying nerve signals. There is a potential difference between the core of the long nerve cell  and the outside of the myelin sheath of the nerve fibre.  The message is transmitted as the potential difference is equalised as it moves along the nerve cell.   I suppose you would call that biological electronics.    I apologise for running off-topic, but I thought it might variously be a little entertaining.

[Restorer32]

When we were kids my brother and I would take one of those large "can" condensers from a discarded TV, attach an electrical cord to the 2 prongs and quickly plug it in and out of a 110 outlet. Those suckers would hold a charge for several hours and would shock the bejesus out of an unsuspecting friend if you touched the prongs of the electric cord to bare skin. Great fun!

[Guest Grumpy's Auto Shop]

On 9/19/2016 at 11:42 AM, padgett said:

Agree particularly for points it is just there to keep the points from burning and to reduce radio noise. For short periods can leave off of the points cars I know.

 

OTOH a good condenser is essential for my AC. Please distinguish which you are talking about.

 

 

That's why you have to replace them every 3000 miles... 

[Guest Grumpy's Auto Shop]

On 9/19/2016 at 0:35 PM, benjamin j said:

In general terms Caps have never been made very precisely, rather, they operate over a range.  Bob Mackie will disagree but he never designed an ignition system.    I am sitting in an office full of electrical engineers none of them are named Bob and they would all disagree with this statement.

 

I was trying not to get into a discussion of precision.  Certainly a part with closer tolerance would be expected to perform better, but good luck getting the bean counters to sign off on it.

I am not an EE but I know enough to be dangerous.

At best, an automotive Iginition Cap was never better than 20% precision, and it will continue to work adequately despite its drifting.  It will do this all the way to the scene of the accident.

(the following has nothing to do with your remarks)
While it is true that a failed condensor can cripple a car, this often is a result of the wiring scheme more than the component's failure.

Either way, it is still SOP to replace it as a regular tune-up item. Just like replacing the right tail lamp when the left one burned out.

 

[Guest]

Back in the 1959-1974 era when I was working in parts at a GM dealer we had about a 5% failure rate on new Delco condensers. Our best tune up man, almost no comebacks, never replaced a condenser unless the points were burnt.  He felt that the odds were better on the old one lasting until the next tune up than a new one.  In 57 years and 400,000 miles on my daily driver I have replaced about 115 sets of points but only about 40 condensers.  My only failure of a condenser was a brand new one.

[Willie Wurke]

On ‎9‎/‎20‎/‎2016 at 8:02 AM, Friartuck said:

Could I get some thoughts on locating a condenser not close to the points? This dual point DELCO distributor is in the front of the engine and the two coils are on the inside of the firewall, some 36 inches of wire away. The condensers are mounted below the point plate which make it a pain to replace. A quick fix in the past has been to hang generic condensers on the 6 volt coil wires outside of the distributor body which looks horrible. Any prediction on attaching the condenser on the coil end. How much does that 36 inch wire make on condenser performance on the points?

 

[Willie Wurke]

Just now, Willie Wurke said:

 

Here is the way I did mine

 

My thoughts for today: All we need to learn is in print somewhere.

                                   if One learns to read there is no limit to his abilities.

                                   I wonder why no one on this thread knows the purpose of the condenser

 

I am entertained by some ideas expressed here on cures for electrical problems.           

[60FlatTop]

If a condenser could write to the Forum we could learn a lot about its characteristics.

Bernie

[Willie Wurke]

Bernie: They can write. They did it years ago; before AACA existed!  Go to your local library if you are old like me. If young use the internet, electricity is fascinating!!

[Restorer32]

Yea but if you ask a condenser a question it tends to blurt out its answer all at once. Sometimes so fast you can't understand it.

[padgett]

Well some of us are automotive/electrical engineers and the tolerance of a cap depends on its intended use. There are precision caps that are +/- 1/10% but are not high power or inexpensive. OTOH in most instances the exact value does not really matter. As to crippling a car, the value does not matter but if it shorts internally, the short will kill a circuit

 

My observation about the dual points was not that they were uncommon, Delco was still making them until the electronic ignitions took over. but that in this case the design of the second set of points was entirely different from the first: the adjustments were different, points were different, even the shape of the arms were different. The upper set looked conventional but the lower set I had never seen an adjustment like that. To rebuild you would need one of each.  This is why I thought they were either modified or aftermarket.

[Willie Wurke]

On ‎9‎/‎22‎/‎2016 at 7:50 PM, Grumpy's Auto Shop said:

 

I was trying not to get into a discussion of precision.  Certainly a part with closer tolerance would be expected to perform better, but good luck getting the bean counters to sign off on it.

I am not an EE but I know enough to be dangerous.

At best, an automotive Iginition Cap was never better than 20% precision, and it will continue to work adequately despite its drifting.  It will do this all the way to the scene of the accident.

(the following has nothing to do with your remarks)
While it is true that a failed condensor can cripple a car, this often is a result of the wiring scheme more than the component's failure.

Either way, it is still SOP to replace it as a regular tune-up item. Just like replacing the right tail lamp when the left one burned out.

 

 

[60FlatTop]

On 9/23/2016 at 0:17 PM, padgett said:

Well some of us are automotive/electrical engineers

 

http://home.pcisys.net/~tbc/sounds/knack.wav

 

 

[Willie Wurke]

On ‎9‎/‎18‎/‎2016 at 8:38 PM, Grumpy's Auto Shop said:

There are two threads currently asking about a specific part working in a particular application.  I don't have an answer for either of these questions but thought I might offer some wisdom.

 

First off, a Condensor or Condenser is in fact a Capacitor.  Its function in a points ignition system is well described in many other places, so I will not repeat it here.

 

It is an electronical [stet] component, the specs of which are not very far from one another in any given points-fired ignition system.  What this means is that the condenser from your lawn mover will also work in your car, with only a few caveats.

 

From an electrical standpoint these caveats have mostly to do with voltage.  A 6v component in a 12v system WILL let the smoke out. (and the smoke is what makes electrical stuff work in the first place...)  A 12v cap simply won't care (as if caps cared in the first place).

 

In general terms Caps have never been made very precisely, rather, they operate over a range.  Bob Mackie will disagree but he never designed an ignition system.

 

It is a matter of fact than 'points, plugs, condenser, cap and rotor' are standard 'tune up' items.  But it is rare that ANY ignition fault was due to the Condenser.  They get replaced because the guy with the wrenches was already there and because the manual says to do it.  It makes sense because the part is relatively cheap.

 

However, this also has to do with fitment.  The Condenser has mostly no concern for its location.  It will function regardless.  (No!  You cant put it the trunk. But it doesn't have to be IN the Dizzy to still function correctly.)

 

The biggest mistake I see is that they are not grounded.  In DC circuits, Caps have to be grounded.  They just do.

I apologize for ranting.  My significant other in law just came to take me for dinner, so I have to press 'submit' instead of editing this post. I hope the info was useful.

The condenser's function is grossly misunderstood as proven by the many posts here. Condensers are not 6 or 12 volt parts. They are rated by their capacity in microfarads and working voltage .

The working voltage is a measure of the insulation inside the condenser. Most of them are rated at about 250 working volts.

Here is what they do: The ignition coil has 2 windings ,a primary and a secondary. When the points close DC battery voltage flows through the primary winding. This creates a magnetic field across BOTH`

windings  When the points open the magnetic field collapses on both windings which causes a high voltage being created in the secondary that is routed to the spark plug. ( It might surprise you to know

that the spark has negative polarity, and all spark plugs are positive ground regardless of which battery terminal is grounded,) While all this was happening the primary got charged up also but he

made AC current which has to be cleaned out before he can take the next charge of DC. This is where the condenser comes into action. IT PASSES THAT AC CURRENT TO GROUND (THAT'S ALL !!)

    A LITTLE ASIDE:  If the condenser  shorts the car wont hit a lick!

                                  If it goes open the car will fire 1 time each time you crank it.

                                          (Just enough to make you keep cranking!!)

 

  AND NOW I WANT TO THANK MR.GRUMPY for starting this thread

          I've had a ball reading all the replies plus the ones sent to me

          I am looking forward to what I just stirred up!

I don't have an official AACA fun meter--If I did it would stay on "MAX"

[Willie Wurke]

On ‎9‎/‎23‎/‎2016 at 10:45 AM, Restorer32 said:

Yea but if you ask a condenser a question it tends to blurt out its answer all at once. Sometimes so fast you can't understand it.

                                                                         Here is 2 condensers that have been having a conversation since 1952. They are on a Delco distributor that has a 3 lobe cam and dual points! 

I'm still running #1 while #2 gets a free ride---the speedo is showing 22000 for the THIRD time!   Bought the car in 1968 . Have never replaced the points.

 Thanks to a very sociable condenser?  ENJOY

[Larry Schramm]

3 hours ago, 60FlatTop said:

 

http://home.pcisys.net/~tbc/sounds/knack.wav

 

 

 

Well, I have "The Knack" and my son also has it when he wants to use it.

[cheezestaak2000]

it's probably very hard to determine the life of a condenser. during the late 60's and early 70's, i worked turning wrenches at an AMC, and a couple of GM dealers. the mechanic approved method on a tune up was to charge out the parts from the parts counter and then NOT install the condenser. obviously you couldn't do that with a uniset, but it was the practice with all others. the thinking behind this was not to cheat anybody, but condensers never seemed to go bad. they would however, cause problems if they worked loose, and it seemed the only time one failed, it was a defective one right out of the box. many of those unused condense rs were used to shock the hell out of unsuspecting service managers