Starter connections SR71x

[Son of Marty]

21 minutes ago, John76 said:

f your car has electronic ignition module (e.g., Pertronix), the resistor wire is not needed, and often replaced (or supplemented) with a straight wire.

John

Or a bosch blue coil it needs no resistor.

[VeroTii]

Thanks for the insight.  My car had an MSD box added at some point.  It is currently disconnected and the car is running a straight setup with a Bosch coil.  As far as I can tell, there is simply a straight wire running to the coil from the fuse box.  What does the .9 ohm resistance do for me?  Obviously it was put in for a reason.  Is is bad to run without it?

['76mintgrün'02]

It looks like you've got a Pertronix installed.  The original Pertronix requires 3 ohms of resistance, but the newest offerings can tolerate less; so the answer depends on which style you have.  

Bosch coils aren't painted anymore, so it isn't as easy to tell them apart.  The "blue" coils have ~3ohms of resistance built in, so they do not require external resistors.  Black and red coils need them if you're running points/condenser, or the early style Pertronix.  You could test the primary resistance of your coil and peek under the cap to see which style Pertronix you have.

 

Step 4: Test the ignition coil’s primary ignition circuit. Ignition coils have two circuits that need to be checked: the primary and secondary ignition circuit.

Connect the positive and negative leads of your multimeter to the positive and negative terminals of your ignition coil. 

[VeroTii]

OK.  I have two coils that came with the car.  An MSD coil and a brand new Bosch coil..  I measure the resistance of both.  The MSD coil shows a resistance of ~0.9 ohms and the Bosch coil shows a resistance of ~1.9 ohms.  Not sure how new the distributor is but it seems pretty recent.  Based on that, it would seem that I do not need the restore wire?

['76mintgrün'02]

It depends on which electronic ignition module you have in that distributor.  If it is an aftermarket Ireland Engineering distributor, their module requires three ohms of resistance.  If it is a Bosch distributor (or IE) with a Pertronix brand module, it depends on which model.  I think the Pertronix I and II require three ohms, but the newer Pertronix III can tolerate less.

['76mintgrün'02]

Okay, I looked up the Pertronix requirements and I was wrong.  The Pertronix II doesn't require 3 ohms and this says the Pertronix I only needs 1.9 ohms.  I guess I don't know much.

 

What is the difference in PerTronix Ignitor and Ignitor II?

 

 

The Ignitor should be used with coils of 1.5-ohm resistance or greater, while the Ignitor II can benefit from higher-powered, super-low-resistance coils. 

[VeroTii]

Thanks for sharing your knowledge.  I will poke around on the distributor a little more and see if I can find a model or serial number.

[John76]

58 minutes ago, '76mintgrün'02 said:

Ignitor II can benefit from higher-powered, super-low-resistance coils. 

I by-passed the resistor wire on my '76 when I installed the PerTronix Ignitor II but kept the original Bosch 1.9-ohm coil.

Just changed to a 0.6-ohm coil as recommended by PerTronix. 45kv to spark plugs...I can shoot down weather balloons!

Ignitor II can use as low as 0.45-ohm or greater coil.

BTW: Ignitor II and III have "adaptive dwell" which works best with super low resistance coils.

John

 

[VeroTii]

No idea what kind of distributor I'm dealing with.  I took a picture of the only markings on the thing.  Recognize it?

[2002iii]

4 hours ago, Jeff McGinn said:

No idea what kind of distributor I'm dealing with.  I took a picture of the only markings on the thing.  Recognize it?

That's a factory BMW distributor.

 

You need to remove the distributor cap and look inside at the part with the red and black wires connected to it.

[VeroTii]

Thanks.  I did but could not find any markings.  I'll try again tomorrow.

[VeroTii]

Well, this is all I have.  No markings that I can see.

[visionaut]

Yeah, that’s the replacement ti/tii mech-only dizzy (188 002).

That’s not a PerTronix, but some other brand of hall-effect electronic ignition…

 

Wasn't expecting ignition Qs in a Starter thread.  lol

 

 

Edited February 16, 2023 by visionaut