• When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.

Replacing the electronic ignition with points - 1977 400 4V

As far I recall, 1.5 ohms is the propper one for points. 0.5 for electronic ignition
 
Blue Brick said:
I have the 2 pin right now. What size do I need?
Click to expand...


In short, to replicate the 1961 - 1972 contact points ignition system ballast resistor, a 0.5 ohm at 70-80 degrees Fahrenheit, open back, thermal/current compensating resistor is required.

The resistor you have now might be okay with points, depending on what resistance unit was in the electronic ignition kit that was installed.

Note that you should have a compatible coil, although your current coil with electronic ignition may be okay. The Chrysler 1960s - 1979 production coil resistance at 70-80 degrees Fahrenheit measures 1.6 - 1.79 ohms for the Prestolite 2444242 type coil and 1.34 - 1.55 ohms for the Essex/Echlin 2444241 type coil.

For more information, about production two terminal Chrysler ballast resistors and some aftermarket replacements, see the following.


The Chrysler ignition ballast resistor used in 1961 through 1972 for the factory Chrysler single contact point distributor is an open back, ceramic power resistor that measures 0.5 - 0.6 ohms at 70-80 degrees Fahrenheit and has specific, expected thermal design properties.

The two terminal 0.5 ohm thermal/current compensating ballast resistor used with the Chrysler point ignition system is part number 2095501, or the superseded numbers 2196316 or 2275590. The late 1970s Chrysler replacement number is 4106140. The Mopar replacement is CH452. These are all 0.5 ohm resistors with open back, and the metal strap, although some later manufactured units might be with a molded mounting hole and sealed back. The Mopar Performance P2095501 is a 0.5 ohm resistor.

Following are a few aftermarket replacement 0.5 ohm ballast resistors:
  • Standard RU-11//RU-11T
  • Wells CR-107
  • Filko CH401
  • Kem FR56
  • Echlin ICR 12
  • Niehoff AL125C
Note that later manufactured aftermarket, or even Chrysler, resistors may be substituted with the 1.2 - 1.25 ohm resistor.

The 1.25 ohm two terminal ballast resistor was first used by Chrysler in 1980 for the "new" 4-pin ECU. The Chrysler part number for the 1.25 ohm resistor is 4106340, superseded to 5206436. The Mopar number is CH458. These resistors have a molded mounting hole with no metal strap and a sealed back. Mopar Performance P5206436 is a 1.25 ohm resistor. Some listings show 5206436 or P5206436 as 1.0 ohm. Others show it as 0.7 ohm.

Following are a few aftermarket replacement 1.2 - 1.25 ohm ballast resistors:
  • Wells CR-107
  • Standard RU-11/RU-11T
  • WVE 6R1007
  • Airtex 6R1007
  • Filko CH901
Note the re-use of the same number for the 0.5 ohm resistor by some of these manufacturers. Resistance may vary more with later production parts.

The 1.2 - 1.25 ohm resistor will work with a point ignition, but the ignition coil generated energy will be less. The current compensation for temperature is not the same though point contact life might be longer.
 
Last edited:
twecomm said:
Understand that a POINTS ignition system, as the diagram Halifaxshops posted previously is different than an electronic ignition system as illustrated in the link I sent earlier showing how the Mopar electronic system works.
In a points system, battery voltage comes from ignition key switch. It is fed to one side of the ballast resistor. in the "cranking" position, the ignition switch electrically bypasses the resistor to feed full battery voltage to one side of the coil. I the "run" position, the resistor is in series with the ignition switch 12 V. and coil feeding a slightly lower voltage to the coil. The other terminal of the coil goes to the points in a "points distributor" to complete the circuit to ground. The cam in the distributor opens and closes the points turning the voltage to the coil on and off. Points closed energizes the coil, points open de-energizes the coil and creates the spark that gets steered to the proper spark plugs via the rotor in distributor cap.
( see link provided ) In an electronic ignition system, battery voltage comes from ignition key switch similar to above.. Battery voltage is fed to one side of the ballast resistor, AND the blue wire to the control module as well. The other side of the resistor feeds the + terminal of the coil on the black wire. In the "cranking" position, the ignition switch electrically bypasses the ballast resistor to feed full battery voltage to the coil. I the "run" position, the resistor is now electrically in series with the ignition switch 12 V feeding a slightly reduced voltage to the coil. The distributor in an electronic system does not have points. Instead it has a magnet and reluctor coil that sends small electrical trigger pulses to the control module as the distributor shaft rotates a star wheel past the reluctor's gap. The control module electronically switches the other side of the coil to ground completing the circuit. Switching action is similar in concept to points opening and closing, but accomplished electronically by the control module ( orange box) and not physically as points do. When commanded by pulse created by the reluctor, the control module electronically completes circuit to ground to energize the coil. When coil de-energizes as the control module turns off the voltage to the coil, the spark is created and steered by rotor in the distributor to the proper spark plug. The distributors for both systems described system is NOT the same. You indicated that : "The previous owner added a control module, a Mopar performance distributor," So yes.. you need to have the control module working if you have the distributor you say you have.
Click to expand...
Great information, thanks for such detail.
 
Vaanth said:
In short, to replicate the 1961 - 1972 contact points ignition system ballast resistor, a 0.5 ohm at 70-80 degrees Fahrenheit, open back, thermal/current compensating resistor is required.

The resistor you have now might be okay with points, depending on what resistance unit was in the electronic ignition kit that was installed.

Note that you should have a compatible coil, although your current coil with electronic ignition may be okay. The Chrysler 1960s - 1979 production coil resistance at 70-80 degrees Fahrenheit measures 1.6 - 1.79 ohms for the Prestolite 2444242 type coil and 1.34 - 1.55 ohms for the Essex/Echlin 2444241 type coil.

For more information, about production two terminal Chrysler ballast resistors and some aftermarket replacements, see the following.


The Chrysler ignition ballast resistor used in 1961 through 1972 for the factory Chrysler single contact point distributor is an open back, ceramic power resistor that measures 0.5 - 0.6 ohms at 70-80 degrees Fahrenheit and has specific, expected thermal design properties.

The two terminal 0.5 ohm thermal/current compensating ballast resistor used with the Chrysler point ignition system is part number 2095501, or the superseded numbers 2196316 or 2275590. The late 1970s Chrysler replacement number is 4106140. The Mopar replacement is CH452. These are all 0.5 ohm resistors with open back, and the metal strap, although some later manufactured units might be with a molded mounting hole and sealed back. The Mopar Performance P2095501 is a 0.5 ohm resistor.

Following are a few aftermarket replacement 0.5 ohm ballast resistors:
  • Standard RU-11//RU-11T
  • Wells CR-107
  • Filko CH401
  • Kem FR56
  • Echlin ICR 12
  • Niehoff AL125C
Note that later manufactured aftermarket, or even Chrysler, resistors may be substituted with the 1.2 - 1.25 ohm resistor.

The 1.25 ohm two terminal ballast resistor was first used by Chrysler in 1980 for the "new" 4-pin ECU. The Chrysler part number for the 1.25 ohm resistor is 4106340, superseded to 5206436. The Mopar number is CH458. These resistors have a molded mounting hole with no metal strap and a sealed back. Mopar Performance P5206436 is a 1.25 ohm resistor. Some listings show 5206436 or P5206436 as 1.0 ohm. Others show it as 0.7 ohm.

Following are a few aftermarket replacement 1.2 - 1.25 ohm ballast resistors:
  • Wells CR-107
  • Standard RU-11/RU-11T
  • WVE 6R1007
  • Airtex 6R1007
  • Filko CH901
Note the re-use of the same number for the 0.5 ohm resistor by some of these manufacturers. Resistance may vary more with later production parts.

The 1.2 - 1.25 ohm resistor will work with a point ignition, but the ignition coil generated energy will be less. The current compensation for temperature is not the same though point contact life might be longer.
Click to expand...
You would need alternator without diodes (old style) and mechanical regulator and old style coil also. EMP would take those out too.
 
Why are we making this so difficult. Just turn the key and hit the red button. We should all know soon enough.
 
The Amish will start up a Uber service and laugh all the way to the cellar.
 
I think we are making this way to hard. One bolt, two distributors and two wires. What could go wrong?
 
We installed a rebuilt points-style distributor intended for a 1972 Mopar 400 engine.

What is the correct ignition timing for a points-style distributor? I currently have it set at 8 degrees BTDC.

What’s the acceptable voltage range for the ignition coil in a points-style system? The ballast resistor is functioning, but I’m seeing just over 9 volts at the coil’s positive terminal, and around 5 volts at the negative terminal. I want to avoid damaging the points or the coil. Should I consider using a ballast resistor with higher resistance to bring the voltage down further?

@HALIFAXHOPS
 
[1] The coil should be designed for use with points ign.
[2] The bal res should be matched to THAT coil.
 
You must log in or register to reply here.

Similar threads

1963JAM
Points or no points? That is the question.
3 4 5
Replies
89
Views
5K
HALIFAXHOPS
HALIFAXHOPS
67belvodere
Difference between stock single points and electronic distributors?
Replies
6
Views
372
67belvodere
67belvodere
E
Electronic distributor and voltage regulators
Replies
2
Views
781
Budnicks
Budnicks
R
New build with untested Electronic ignition
Replies
8
Views
476
Russmacman
R
road robert
Distributor Replacement Referral - Joe's Mopar Distributor Restoration?
Replies
15
Views
857
HALIFAXHOPS
HALIFAXHOPS
Auto Transport Service
Back
Top