Resistor-less rotor for MSD applications

[Pazuzu]

All of us who run the MSD box know that we need a resistor less rotor in the distributor, or it has a chance to melt down. The Napa part EP407 is the classic solution, but it is getting harder to find, and might have been superseded with a resistor rotor in the past 2 or 3 years.

Someone found a different source, the rotor for a 1981 BMW 528i (and maybe other years). There was a Bosch part apparently which is NLA, but there are cheap aftermarket versions, all using the part number GB330.

Well, I found this on "rock auto":
https://www.*thatwebsitename*.com/en/parts/standard+motor+products,GB330,distributor+rotor,71 36

Closeout (for now) pricing, 72 cents each. I bought 5 and payed for the priority mail shipping, total was $8.59. I figured I'd either get 5 good rotors, 5 bad rotors, or a mix.

I got a mix


On the left is the EP407 that I removed from my car, it had 3 years and about 25,000 miles on it.
The 5 pack sent me 2 black rotors (one now in my car), and 3 red ones. You can see that there are 4 different types. The black ones are clearly resistorless rotors, like the EP407. The red ones come in three flavors. The far right is a resistor rotor with a resistance around 5K ohm, like the factory Porsche part. The center red rotor also has a 5K ohm resistor. The #4 rotor looks like it has a resistor (with the epoxy), but it';s actually a resistor LESS rotor with epoxy over the solid brass connection.


So, for $8.59 I got 3 resistor LESS rotors (and two resistor rotors that I can toss in the trash).

I suggest that you all go and buy 4 or 5 of these, find 1 or 2 that you like, and we can all move past the EP407 debacle

[Pazuzu]

Oh, they came in two different boxes, with the same GB330 part number. 3 were "Standard Motor Products" and 2 were "Carquest".

[IMONBOOST]

I was not aware that we should be running resistor less rotor with MSD, nice to know as I just purschased and installed a Beru, have to go check it out.

[rwest]

MSD has more "juice" and will melt out the resistor in the rotor after awhile. There is at least one thread showing how to Dremel out the resitor and solder in a piece of solid wire to make a resistorless rotor.

This would be the way to do it if your model uses a RPM cut out rotor.

[911parts]

OK good info Pazuzu, need a black one how and from whom do I get it?

Thanks

[juanbenae]

NAPA auto carries one. I found a part number here in searching "napa rotor". I had to order it, so got two.

[Bob Kontak]

Originally Posted by juanbenae

NAPA auto carries one. I found a part number here in searching "napa rotor". I had to order it, so got two.

Yep. Bought five a few years back. Maybe $8 per back then.

[911parts]

OK so what is the number? From search/pic GB330 is resistor-less, is that still the case? From search/pic Echlin EP407 isn't. Even at Napa if they bring up a pic it looks resistor-less but when it arrives it isn't

[911 SLANT]

So with MSD resistorless is the way to go?

[zedsn]

Yes with MSD resistorless is the way to go. I just removed the resister and soldered in some 12 gauge wire to my limiter rotor last week.

[juanbenae]

MSD SC rotor mod

I ordered two cause my "local" napa store like 12 miles away had to special order them. ^^^^

[911 SLANT]

Does Napa still sell the 407 rotor

[Sebscst]

I have ordered mine on amazon.

[911 SLANT]

Do you have a Part number?

[faapgar]

The one from NAPA works.Color may vary.Ciao Fred

[911 SLANT]

I checked online. Out of stock. Haven't found a local Napa that has them.

[Reiver]

Originally Posted by 911 SLANT

I checked online. Out of stock. Haven't found a local Napa that has them.

They ordered them for me and I got a bunch at the time....it took awhile as they had to gather then from stores around the country...but they had them.

[chapo]

Milled out the rester on mine, then epoxied a chunk of copper in. Pretty easy, has lasted for years

[dicklague]

I HIGHLY recommend using the soft rev limiter in your CDI raather than that awful rotor limiter. That thing is brutal, like hitting a wall.

I know many MSD have limters built in. I don't think MSD is good quality, so I don't keep track of their features.

I got rid of my rev limiting rotor and set my Daytona-Sensors CD-1 to 6600 RPM. It is a great soft limiter a just starts stuttering, rather than shorting the ignition. I also like being below the 7200 RPM redline. my 1973 has a wonderful MFI 2.7 Carrera spec motor built on 7R cases by Mark Kinninger, and I was to keep it to 6600 RPM. It has 150,000 miles on it in 20 years of driving and is in excellent shape. I want to protect it.

Also, if you are in the market for a CDI look at the Daytona-Sensors CD-1. Fabulous quality, and comes with a matching coil. Excellent detailed instructions and tech support.

MSD, CRANE , CD1 COMPARO
http://nebula.wsimg.com/27b2f71620e4055fc5928d34fb516ad4?AccessKeyId=1C324 6E298A5DEFACC7D&disposition=0&alloworigin=1

[911 SLANT]

Just ordered 2 from O'Reilly for 3.00 dollars each. Have them by tomorrow.