Bosch ZR6 magneto question

[alsfarms]

I have never had a Bosch ZR6 magneto before. Is it a true statement that all Bosch ZR6 magnetos are two spark? If not, how do you determine a single spark application and a two spark application.  Please post a picture that I can learn from.

Al

[DFeeney]

I also would be interested in learning the answer. Thank you for posting,

[Mark Gregush]

Looking online at images I found images of both twin and single fire ZR6's. Twin fire would be for 6 cylinder engines with 2 sparkplugs per cylinder. Dual would be for firing on either magneto or regular coil/battery setup.

[alsfarms]

I am curious on how to tell the difference between the two spark version and the regular or single spark dual. Can any one offer some assistance with this ZR6 identification question? Does the magneto serial number offer any help.

Al

Edited September 21, 2023 by alsfarms
Clarity (see edit history)

[edinmass]

Dual means battery/mag.

Twin Spark means dual plugs per cylinder. 

[alsfarms]

Each type magneto requires the correct coil switch to function either as a conventional or dual system.

Al

 

[mikewest]

Al, how many sets of points does it have?

[Mark Gregush]

5 hours ago, alsfarms said:

I am curious on how to tell the difference between the two spark version and the regular or single spark dual. Can any one offer some assistance with this ZR6 identification question? Does the magneto serial number offer any help.

Al

You are sitting at the computer, why don't you try doing a search on the internet. And no, the serial number does not help. Post a photo of the one in question. 

[JV Puleo]

Al...I have a ZR4 for the MItchell. It's a dual...meaning it can run on either mag or bat. That was the common configuration and intended for use with a single plug. I believe the twin spark mags have two sets of points and a different cap that accepts two sets of plug wires. The ZR mags used a special buzzer coil mounted either on the dash or floor and could be wired to work either entirely from the switch or so that "bat" was engaged automatically when starting (if the car had an electric starter) and then could be switched to "MAG" once it was running. I've been told that you have to use the Bosch coil. I am not completely convinced of that and will eventually do some experiments since I don't know enough about electrical engineering to calculate what will work but a coil is a pretty simple device so my guess is that either a modern coil or some other buzzer coil could be adopted.

 

I believe it was introduced in 1912. Bosch serial numbers seem to run consecutively regardless of model so you can date them from the SN but that's all. I found a SN listing with dates on-line somewhere. I have the wiring diagram somewhere as well and will send it if you need it.

[alsfarms]

Mark and Joe,

Thanks for the comments and advice. I must be first to say,I am no "wizard" when it comes to internet searches. However, I have stumbled around enough searching to learn that not all ZR6 magnetos are two spark. In fact I now guess that the two spark version is actually quite rare in the ZR6 configuration. I am guessing that many more Dual magnetos were produced as ZR6 versions.  My misconception made me think that all ZR6 were two spark...and wrongly so.  I have studied a few pictures and have determined that what I was being encouraged to purchase is in fact a "Dual" not a "two spark" design. Joe, If you run across your wiring diagram, I would be thankful for a digital image to study. One additional question, I assume that a "DR" is an older design that a "DU" and a "ZR" is likely newer than both of these designs or do they all overlap?

Al

[Guest]

Here's the wiring for the ZR6 Dual Ignition System.

 

The dual ignition magnetos say "Dual" on the base. I think the Twin Spark magnetos say "Twin Spark" on the base.

 

[alsfarms]

Thanks....

 

[JV Puleo]

Al, you are correct. The two spark mags are very rare. I think I've seen only one for sale in the past few years(though I confess I don't look for them). This is largely because most two-plugs per cylinder engines used both a battery and mag ignition so the mag never handles more than one set of plugs.