11 replies to this topic

[jiminwatford]

Watching this video from AC Dodd https://youtu.be/Vnv...26Id1Xde4hSWqdo it would seem i should have a coil measuring 0.8 ohms. I have a 65d distributor with electronic ignition from a 1988 Metro

 

The coil currently fitted measures 1.5 ohms and apparently should have a ballast resistor. I don't know if it has. Are they inside the coil or located separately? I don't know if i should fit the 0.8 ohm coil. I don't want to connect it up and cause damage by having a ballast resistor with a coil which shouldn't have one

 

I don't know if this is any help but this is the wiring at the coil

 

 IMG_20230407_114325_528.jpg   92K   3 downloads

[nicklouse]

https://www.theminif...tributor-types/

https://www.theminif...ignition-check/

 

some reading for you.

[jiminwatford]

https://www.theminif...tributor-types/

https://www.theminif...ignition-check/

 

some reading for you.

 

Yes the car has the 65d distributor with electronic ignition and should have the 0.8 ohm coil

 

However it has a 1.5 ohm coil (and has been running with it for years) which should have a ballast resistor

 

What i'm wondering is if there is a separate ballast resistor installed and i fit the 0.8 ohm coil will it do harm. Or would the ballast resistor be part of the coil currently fitted?

 

I included a picture of the wiring of the coil to see if that showed if there was a separate ballast resistor fitted. Or can i simply connect all three leads to the new coil?

 

I'm wanting to replace a 1.5 ohm coil with a 0.8 ohm coil and i don't want to damage anything

[KTS]

The ballast resistor is typically just a length of resistive wire that drops the voltage supplied to the coil from 12volts down to about 8volts (I think)

[timmy850]

There were 3 factory setups:

3 ohm coil and no ballast resistor (points)

1.5 ohm coil and ballast resistor (points)

0.8 ohm coil and 65D variable dwell distributor

 

If you run 1.5 ohm and 65D and no ballast wire it will work OK, but not have the full spark power

If you run 1.5 ohm, 65D, ballast wire it'll run pretty poor

 

The ballast wire is usually pink and would go to the positive side of the coil. Where do the existing wires go?

[jiminwatford]

Basically i think i'm looking to find out if the car has a ballast resistor or not. I can see there are posts on how to check for that. I'll check them out later

 

[jiminwatford]

There were 3 factory setups:

3 ohm coil and no ballast resistor (points)

1.5 ohm coil and ballast resistor (points)

0.8 ohm coil and 65D variable dwell distributor

 

If you run 1.5 ohm and 65D and no ballast wire it will work OK, but not have the full spark power

If you run 1.5 ohm, 65D, ballast wire it'll run pretty poor

 

The ballast wire is usually pink and would go to the positive side of the coil. Where do the existing wires go?

 

I'm not sure where they go. I can find out. The car is a 1986 City with a 1988 Metro 1275 with its 65D dizzy. It doesn't run terribly and recently rolling roaded with the 1.5 ohm and 65D. What made me get the new coil was watching AC's videos where it's clear the 65D should pair with the 0.8 ohm dizzy

 

I think i'm hedging that there isn't a ballast resistor but more checking on where the wires go i think is needed

[timmy850]

Check the voltage at the positive side of the coil when the key is on

[Steam]

There is a school of thought that a 1.5 ohm coil without ballast will give longer life for the module (on the side of 65d) whereas a .8 ohm can cause premature failure. I do not know either way but a 65d will run fine with a 3ohm, 1.5ohm or 0.8ohm and I doubt you would notice the difference. The higher the coil resistance the less current the module has to cope with.

[timmy850]

A 3ohm coil will give approximately 1/4 of the spark power as the 0.8ohm - and if you add this to the variable dwell of the 65D it'd give very poor spark power. 

[Steam]

I can tell you from experience that a 3 ohm coil makes very little difference. It was GT40 mind.
Been there done that.

[jiminwatford]

Checked the voltage of the existing coil and it was 12.5v so assuming no ballast resistor. I've fitted the 0.8 ohm coil and all seems well

 

Thank you