Distributor ignition rotor fried, Anyone know why? Options

[jcambo7]

So after a little over three years I finally got some free time and money to get my 914 running again. Got her started up after changing oil, filter, and cleaning the gas tank. While I was trying to start it again after it quit running while I was tuning the carbs I found the ignition rotor to be fried and melted a bit.

[Dave_Darling]

Heat melted it. (No s**t, Dave!) The heat is likely caused by resistance and lots of current. Usually there is a decent amount of current and very low resistance here.

First, do you have a "super" coil of some kind? The 914 seems to work best with a coil that has a resistor, either incorporated into the coil (as in stock or Bosch blue coils) or externally.

Next, what does the inside of the cap look like? How about the connections on the plug wires, and the plug itself?

--DD

[jcambo7]

Heat melted it. (No s**t, Dave!) The heat is likely caused by resistance and lots of current. Usually there is a decent amount of current and very low resistance here.

First, do you have a "super" coil of some kind? The 914 seems to work best with a coil that has a resistor, either incorporated into the coil (as in stock or Bosch blue coils) or externally.

Next, what does the inside of the cap look like? How about the connections on the plug wires, and the plug itself?

--DD

I have an MSD coil. The cap, wires and plugs look fine. No burn marks or fried wires elsewhere.

[michael7810]

The rotor in my car lasts about 8-10K miles before it fries. Never looked as bad as yours but the epoxy on top burns and cracks and that causes a severe misfire. I just changed it after 6K miles because the epoxy was getting black although it was still working OK. I have MSD and set my plug gap at .042. I figure the MSD plus larger plug gap are causing the shortened life.

[yeahmag]

If you're using a high-performance coil, you need to dig the resister out of the epoxy. From there you will need to solder in a piece of stranded copper wire to take its place. I believe John at aircooled.net sell these premade.

[michael7810]

If you're using a high-performance coil, you need to dig the resister out of the epoxy. From there you will need to solder in a piece of stranded copper wire to take its place. I believe John at aircooled.net sell these premade.

Thanks. I'll contact John and see what he has. I'm using an MSD Blaster coil

[porschetub]

Looks like he is running a six,skipped MSD has not proved to be up there for dependable service,other opitions are out there.
Massive resistance @ that rotor,bad leads or fused points....who knows,don't understand why anyone runs points anymore...that's the bottom line.

['73-914kid]

CB Perfomance sells a new rotor with just a brass strap. No funny business with soldering in a heavy wire. Only downside is that you lose the ability to run a Rev limiting ignition rotor.
https://www.cbperformance.com/product-p/2004.htm

[jcambo7]

Looks like he is running a six,skipped MSD has not proved to be up there for dependable service,other opitions are out there.
Massive resistance @ that rotor,bad leads or fused points....who knows,don't understand why anyone runs points anymore...that's the bottom line.

It is a six. I had the pertronix magnetic pick up on it when I bought the car but it kept having issues. I went through two or three of them. When I had sixnotfour look at it since he built the engine he swapped it back to points.

['73-914kid]

Do you run an MSD box, or just the MSD coil with pertronix?

[jcambo7]

Do you run an MSD box, or just the MSD coil with pertronix?

MSD 6AL box and coil. No Pertronix.

[yeahmag]

Do you run an MSD box, or just the MSD coil with pertronix?

MSD 6AL box and coil. No Pertronix.

Yeah... That's absolutely what's causing the failure. Use the 6AL to limit the rpm and a non-limiting rotor.

[sixnotfour]

Have John get you e non rev rotor from worldpack

[jcambo7]

Have John get you e non rev rotor from worldpack

Bovey?

[michael7810]

CB Perfomance sells a new rotor with just a brass strap. No funny business with soldering in a heavy wire. Only downside is that you lose the ability to run a Rev limiting ignition rotor.
https://www.cbperformance.com/product-p/2004.htm

That's a smokin' deal if it fits your distributor. I don't think it will fit mine and just ordered one from Airooled.net for 3.5X the price to fit my Aircooled.net SVDA.

[Mark Henry]

Looks like he is running a six,skipped MSD has not proved to be up there for dependable service,other opitions are out there.
Massive resistance @ that rotor,bad leads or fused points....who knows,don't understand why anyone runs points anymore...that's the bottom line.

Sounds like you've been talking to guys using cheap ebay Chinese MSD clones. Sure a MSD can fail, but it doesn't happen often to the real deal. The old 6al is gold to the V8 crowd up here.
Nothing wrong with running a MSD with points, with a MSD the points become a simple low voltage on/off switch, they don't burn like on a stock system.

I've seen more pertronix failures than points failures. On the side of the road I can fix points with a screwdriver and a folded business card. Failed pertonix and yer done, call AAA.

I agree ditch the rev limiting rotor and use the MSD for rev limiting.

[HarveyH]

Do-it-yourself project:
High Energy Rotor

(IMG:style_emoticons/default/welder.gif)

[yeahmag]

That's exactly how I did it before I switched to a Mallory Dizzy.

[jcambo7]

Could this had fried the distributor also if I kept trying to start the engine a few times or more before I noticed the rotor being fried?

['73-914kid]

I would be very surprised to see any damage to the points. With an MSD box, they are just a trigger mechanism.

For a quick test, grab a vw type 1 rotor (with resistor would work fine for a quick test) and try and start it. Brief running time on the rotor won't damage anything.