Defective condensor effects !

BUBBAS IGNITION

BUBBAS IGNITION

Well-known member
More common than i would like to see ! Customers sent in distributor for testing with a missfire when engine was running.
A quick visual shows some arcing at the contacts. Hook up on machine to run and bingo ! I bet it really did missfire .
Two clues here , 1- heavy blue arcing at the contacts shown in picture and missing firing lines on tester ( should be 8 evenly spaced lines).

101_0194_zps25845df5.jpg


101_0195_zpsacc6eadd.jpg


A quick test lead condensor (known good one) was tryed with the following results;

Contacts quit arcing and all eight cylinders are shown....

101_0196_zps0f59c45d.jpg


101_0197_zpscf2e5c89.jpg


Now lets discuss why this happens...........:eek:
 
Jets in carburetor too small! :D:D:D
BUBBAS IGNITION said:
More common than i would like to see ! Customers sent in distributor for testing with a missfire when engine was running.
A quick visual shows some arcing at the contacts. Hook up on machine to run and bingo ! I bet it really did missfire .
Two clues here , 1- heavy blue arcing at the contacts shown in picture and missing firing lines on tester ( should be 8 evenly spaced lines).

101_0194_zps25845df5.jpg


101_0195_zpsacc6eadd.jpg


A quick test lead condensor (known good one) was tryed with the following results;

Contacts quit arcing and all eight cylinders are shown....

101_0196_zps0f59c45d.jpg


101_0197_zpscf2e5c89.jpg


Now lets discuss why this happens...........:eek:
Click to expand...
 
A condensor has three very important design parameters or functions.

1- Series resistance
2- Leakage
3- Capacity ( measured in mfds)

1=The series resistance allows some resistance to ground and current flow. The condensor will allow a small amount of current to flow thru to ground, but not very much. Too much flow and the contacts cant make or break the circuit as it would be a direct circuit to ground.
2=Leakage is the small amount of flow allowed to ground, again only a small amount of controlled leakage is designed.
3=Capacity is the amount of MFDs the condensor can hold or store allowing the contacts to open and close without arcing.

Each of these specs are very important in the operation of the ignition system , allowing the contacts to act as a switch (on/off ).


In the case above the condensor failed the capacity test . Only allowed a small amount of capacity (tested a .10 mfds on tester). This caused the contacts to arc loosing control of the proper on/off switch of the primary coil, causing a missfire...
 
Further effects of a sub-standard condenser:

These contact points were replaced after 10,000 miles with the stock condenser made in Argentina:

IMG_3722.jpg


As you can see, metal has migrated from the arm contact to the base contact. This is a result of too much storage capacity. Too little storage capacity will cause the metal to migrate from the base to the arm contact. (Read more here: http://www.farmallcub.com/phpBB2/viewtopic.php?f=11&t=38576) These points worked OK with the condenser but not as well as below.

Now, here are the contact points I just replaced that have run 10,000 miles on the ASC condenser that Bubba sells:

Base:

DSCN2691-R_zps168422e7.jpg


Arm:

DSCN2692-R_zps4c04de9e.jpg


You may not be able to tell it from the pictures but there is no migration of metal between the points - a little charring, but no migration. These points would not have to have any "nipple" filled off to gap them (although they are worn enough to be replaced).

This is the condenser Bubba supplied me:

DSCN2696-R_zpsbc92426b.jpg


It is rated at .360 mF but actually measures .351, well within the 10% margin of error stated.

As suggested in the article I linked, since the condenser is perfectly matched to my ignition and is not causing any migration of metal. I'm not replacing it.

Just thought someone might like to know.
 
Last edited:
Henry,

Good post glad to see the report on the vertex Mag distributor condensor.
What brand of contacts are you using ???
The difference between a 12 buck set of points and 22 buck set is usuall seen in brass straps, basic construction and the coating of platinum on the actual contacts.
For example a set of contacts for a Vertex mag runs over $ 100 for a single set , however the platinim coating makes them almost a lifetime set up.....

We use the NAPA CA$& for all our builds seems to be a good set of contacts etc......
 
What condenser should we use for helmet style distributor. The one you shown is for the later style thks John
 
Is there any difference between 6v and 12v condensers? What condenser should I be using in a crab style distributor running 12v and an aftermarket coil?
 
BUBBAS IGNITION said:
The difference between a 12 buck set of points and 22 buck set is usuall seen in brass straps, basic construction and the coating of platinum on the actual contacts.
For example a set of contacts for a Vertex mag runs over $ 100 for a single set , however the platinim coating makes them almost a lifetime set up.....
Click to expand...
Speaking of platinum points, recall that back in the 50's one of the things we used to do is take our points to the local jewelers to have a coating of platinum brazed on them. That's when platinum was cheap.
 
Question for Bubba,

I have been told that the 12v condensers would work with a 6v system, based on the milifads is this true? I was given a large box of 12 and 6v condensers, (n.o.s.) stuff from back in the day and would like to keep a few in the glove boxes of my trucks.
 
41panelmark said:
Question for Bubba,

I have been told that the 12v condensers would work with a 6v system, based on the milifads is this true? I was given a large box of 12 and 6v condensers, (n.o.s.) stuff from back in the day and would like to keep a few in the glove boxes of my trucks.
Click to expand...


The mfd ratings are usually given out in 200-300 volt ranges or more .... Six and 12 volts dont really figure in the equation and even if they did it would every so small amount....
 
41panelmark said:
Question for Bubba,

I have been told that the 12v condensers would work with a 6v system, based on the milifads is this true? I was given a large box of 12 and 6v condensers, (n.o.s.) stuff from back in the day and would like to keep a few in the glove boxes of my trucks.
Click to expand...

Back in what day? Be carefull with old condensers they can go bad just as a matter of time.
Agree with bubba, 6 or 12 makes no difference that's important, they are not sensitive to such a low difference in voltage. Only number to worry about is mfd.
Martin.
 
scooder said:
Back in what day? Be carefull with old condensers they can go bad just as a matter of time.
Agree with bubba, 6 or 12 makes no difference that's important, they are not sensitive to such a low difference in voltage. Only number to worry about is mfd.
Martin.
Click to expand...

So what mfd number should we be looking for with a flathead? I measured mine at .325, my one set of points looks perfect, the other has some minor pitting.
 
Automotive Stud said:
So what mfd number should we be looking for with a flathead? I measured mine at .325, my one set of points looks perfect, the other has some minor pitting.
Click to expand...

Flathead helmets should test at .32-.36 mfds ...
One set of points ( drivers side) should always look worse than the other side. As one set makes the circuit ( closes-pass side controls dwell) and the other breaks the circuit (drivers).
The actual current flowing is broken with the drivers side and the condensor helps take some of this snap away needing the larger of the .36 mfds spec....:)
 
BUBBAS IGNITION said:
Flathead helmets should test at .32-.36 mfds ...
One set of points ( drivers side) should always look worse than the other side. As one set makes the circuit ( closes-pass side controls dwell) and the other breaks the circuit (drivers).
The actual current flowing is broken with the drivers side and the condensor helps take some of this snap away needing the larger of the .36 mfds spec....:)
Click to expand...

Thanks for all of the great info! Slightly off topic, but with a points ignition what should the total amount of resistance be? 3-4 ohms?
 
I seem to have solved my ongoing Condenser problem by finding and tightning the wires attached to the resister under the Dash. .....So I went and checked all the connections I could find and now the starter even turns over better and the 6V Lights are brighter. Good clean tight electrical connections = good performance! I might even take a little night drive now.
 
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