[Mahler9th]

You have my empathy on this one. I have been having some strange issues with my twin plug set up. Twin MSD units, Blaster 2 coils and a JB Racing distributor.

We may be having similar issues. Longshot, but possible.

Here are some things to think about:

I have used Blaster 2 coils and MSD boxes since 2001. I have had two coil failures in all that time. I carry 2-3 spares. I also carry a spare 6AL, but I have never had one fail.

The oil-filled Blaster 2 coils do not like to be mounted upside down. I learned this in 2002 in the first ever PRC race. Of course the potted coils should eliminate this possibility. Hard to imagine MSD having issues with Blaster 2 coils since they sell so many.

It sounds like you think at least one issue may have a thermal component. If there is any way to confirm or refute that, it might be really helpful.

The caps sold by JB Racing are replica units from a factory in Italy. You can find the same caps at places like Amazon. I think they all come from the same place. I had one fail-- the center electrode just disintegrated. I still do not know why.

I have tried several different caps, and in some instances my rotor has had physical contact with the contacts in the cap. Its just not clear to me that the caps have tight manufacturing quality control and/or tolerances. Not sure how I feel about that.

I have had had quite a few conversations with JB Racing since I bought my distributor in 2017. At first I just could not get it to work. I even sent it back to them and they tested it. I think it is a fine product.

I am really impressed with them-- I feel we are lucky to have them making and selling these distributors.

I would be surprised if they had any manufacturing issues, but I would not be surprised if they have at least some vulnerability with respect to component suppliers. Hard for anyone to avoid that with such a product.

I might attempt to use both pickups in an experiment to see if one might be wonky. I have seen situations where factory distributors developed thermal issues. I am sure that many out there have. I wonder if it is possible for the pickup JB Racing uses to have a similar situation occur. Need to really think more about that-- perhaps a thermal issue where the pickup goes dead or intermittent.

I do not think that picking up the MSD tach output for an AIM system can cause the type of issue you are having.

Plug wires... I started out with a good used set of 993 wires that I re-terminated for the JB Racing cap. These wires had worked fine when I had a 993 distributor (that distributor failed due to a bad bearing-- cost me a crankshaft). As part of my troubleshooting I invested in a set of Clewitt wires, Excellent parts and I do not regret my investment.

There are several ways to wire the MSD's-- there is at least one other thread on this topic in these forums to which I contributed some diagrams/concepts.

My boxes are now connected in series. The tacho output of the first box feeds the points input of the second box. It also goes to AIM and my Haltech ECU.

So for box one, if there is a failure that kills its tacho output, the engine won't run. I will see no rpms on AIM, and neither the second box nor Haltech will not be able to operate.

The tacho output of my second MSD box goes to an rpm switch set at about 2k rpm. So when the revs are below 2k, the NC contacts of this switch light up a small dash light. Above 2k, that light is out.

So I effectively have a system that will warn me if one or both of the MSD boxes tacho outputs stop.

But that only helps if all MSD failure modes result in a dead tach output signal. I have not asked MSD about this nor studied their circuit topology.

I think MSD can test their boxes for a fee. I might look into this.

Let's all work hard to get this sorted.

No fun to troubleshoot stuff like this.

The apparent thermal nature may be a big hint.

Heat gun and distributor testing machine... hmmmm.