pertronix install, pre ignition and starter stumble

[walkinfool]

Hello all, I have a '72, carbureted, mechanical advanced distributor set up and have been running a points ignition system. Though I haven't had any issues with this system, I've been wanting something a bit more reliable and decided to upgrade to an electronic ignition. And, after reading way too many posts and watching far too many YouTube videos on electronic ignition I decided to go the Pertronix route (though the 123 Bluetooth ignition looks like a decent, future option). Anyway, the Pertronix went in fairly easy and after changing to the recommended black Bosch coil, I installed new ignition wires and plugs. (the cap and rotor are fairly new).  I'm getting a timing light this weekend and so I didn't have a chance to check timing after the install but decided to start the car anyway. The starter labored as though it wasn't getting enough juice and then the car fired right up. it idled fairly nicely too and I didn't hear any missing or pinging. I've not had starter issues before this and the battery was fully charged so was wondering if this sounds like pre ignition and maybe the timing is just a few degrees too advanced? Thanks in advance for your thoughts!

Mitch

[Jae]

What coil did you have before changing to the black? 

[Tdh]

You'll need to check/reset your timing.   The act of installing the pertronix module and setting the air gap (dwell factor) subtly changed your timing.  

 

Also, do yourself a favor and buy a nice timing light.  The kind that allows you to set advance/retard.  

Edited April 3, 2020 by Tdh

[walkinfool]

20 minutes ago, Jae P said:

What coil did you have before changing to the black? 

Bosch Blue.

[walkinfool]

19 minutes ago, Tdh said:

You'll need to check/reset your timing.   The act of installing the pertronix module and setting the air gap (dwell factor) subtly changed your timing.  

 

Also, do yourself a favor and buy a nice timing light.  The kind that allows you to set advance/retard.  

yes, I figured it was timing related. thanks for the timing light suggestion. I'll be looking this weekend, if parts stores are open that is. thanks and stay safe!

 

[Jae]

16 minutes ago, walkinfool said:

Bosch Blue.

When you made the change, did you add a resistor since the blue has an internal one? My understand is with a pertronix, you have to run a resistor with black or red coil but bypass it if you have a blue coil. 

[Tdh]

Jae P,

 

I'm not looking at the exact coil he has, but primary resistance of blue coil 3.2, black is 3.0 (provided he has the longer black coil).  He would have been fine to keep the blue coil.   

 

Bosch red coil IIRC has primary resistance of 1.6 (maybe 1.8), and would need to be used with a ballast resistor.

 

 

Edited April 3, 2020 by Tdh

[Jae]

I asked because I went through the same symptoms and and have the same set up until I added a resistor. But I did adjust my timing before I stated it afterwards and all was well. Something to look out for.

[walkinfool]

honestly, I read so much on the FAQ before I did the swap that I was googly eyed. ultimately, I headed to Steve at Blunt for the advice on the coil. I was using a ballast resistor with the blue coil and points set up but the pertronix instructions said to keep the ballast resistor so that's what I did.

['76mintgrün'02]

If you add a multi-meter to your shopping list you can test the resistance in that black coil and know exactly what you have.

 

Nowadays, coils come in all sorts of colors and resistance values, but typically the black coil does require a resistor and so do the red ones.  The blue usually have resistance built into them.

 

I have this timing light and really like it.  It was available online with free delivery for around a hundred bux but it's gone up a bit, it seems.  Still much cheaper to order it online than the NAPA store up the street from me, where it's $180.

 

https://www.summitracing.com/parts/ino-5568?seid=srese1&gclid=EAIaIQobChMIrr725K7N6AIVlddkCh0cOgEGEAkYASABEgJvIPD_BwE

[walkinfool]

1 hour ago, '76mintgrün'02 said:

If you add a multi-meter to your shopping list you can test the resistance in that black coil and know exactly what you have.

 

Nowadays, coils come in all sorts of colors and resistance values, but typically the black coil does require a resistor and so do the red ones.  The blue usually have resistance built into them.

 

I have this timing light and really like it.  It was available online with free delivery for around a hundred bux but it's gone up a bit, it seems.  Still much cheaper to order it online than the NAPA store up the street from me, where it's $180.

 

https://www.summitracing.com/parts/ino-5568?seid=srese1&gclid=EAIaIQobChMIrr725K7N6AIVlddkCh0cOgEGEAkYASABEgJvIPD_BwE

I have a multi-meter and plan to check resistance. Thanks for the info on the timing light. I ran across that one earlier when I googled top timing lights. Looks like a good one. Best, Mitch

[Chris_B]

Sorry if this was said above, but slow cranking is a classic sign of retarded timing. 

[rcf925]

When I installed my Pertronix, I just called Pertronix to get the info from the horses mouth so to speak, They just asked me for the number off my Pertronix and recommended a 3 ohm coil which I bought and installed, Runs perfect

[walkinfool]

On 4/3/2020 at 7:02 PM, Chris_B said:

Sorry if this was said above, but slow cranking is a classic sign of retarded timing. 

Thanks for weighing in. Indeed, I was off a few degrees and after rotating the dizzy clockwise just a pinch she fired right up with no stumble, purred like a kitten at idle and ran great on the test drive. Still plan on confirming with a timing light but I think I’m pretty close.