MSD Rotor Modification In Detail

[gavinc69]

Just ordered MSD 6425 6AL Digital, High Vibration Blaster Coil, Magnecor KV85 Leads, New Cap & Rotor and new Plugs.

After reading many posts I think It's a good idea to modify the Rotor to remove the resistor so I don't get a melted Rotor.

I found these detailed insatuctions and seeing as people seemed to be requesting such info thought I'd post them.

Brand new Rotor :



In order to remove the epoxy, and get to where we will be soldering a piece of wire, you will need a dremel (or equivalent), and a couple bits.


Use the large bit, and remove all the epoxy in the large areas, that the bit will fit into. Go slow! Also: The orange piece of the rotor is some kind of ceramic, it is much harder than the epoxy, so don't worry too much about ruining that part. The resistor is in the larger-front middle section (you will be dremeling through it, so don't worry about it either).




Now you can continue to dremel the rotor with the small bit, so you can get into all the small crevices. If you do it right, there will still be enough epoxy holding the center and tip pieces in. This is what it should look like when you are done dremeling:

[gavinc69]

What you want to do is strip off about 2 inches of the wire insulation. Then put some flux on both ends of the wire, AND the brass "O" rings in the rotor. Carefully slide the wire in the brass "O" rings, and cut the wire to proper length. Once in place, solder the wire inside the brass "O" rings:





Now the 'hard-part' is over! The next step is to fill the rotor cavity back up with epoxy. Almost ANY epoxy will do, but I found it best to use at LEAST a 15 minute epoxy (I used a 30 minute), this way you have plenty of time to get the epoxy in, and work it around, and tamp it before it dries. You CAN buy colored epoxy (to make it look like the original), but I prefer clear; With it clear, you can tell its a modified rotor, plus it looks kinda cool!

Once you mix up the epoxy, I found it best to 'pour' it into a syringe. It is best to pull out the 'plunger' and pour in the epoxy from the top. Then you can get the air out, and squeeze the epoxy out. All you have to do now, is carefully start to fill up the rotor with the epoxy. Fill it up to about the same level as it was originally. You may find it helpful to work out some of the air bubbles, and fill the cavities better with a toothpick. You can find the syringes at Walgreen's (or any pharmacy):

Its hard to see in these pics, but this is what it looks like when the epoxy has cured (a full 24 hours is preferred).






You can kinda' see the 'level' of the epoxy in this pic:

[sc_rufctr]

Excellent write up... Thanks.

[CharlieB]

Great write-up. What guage wire did you use? Aluminum or brass core??

[gavinc69]

This was used: stranded 16Ga. or heavier wire (I used 12 Ga. If fits PERFECT!), some flux, some soldering wire, and a solder-gun.




I used a heavy duty-high heat gun (below), but a standard one will work also:

[dicklague]

Great write up.

It is important to get the copper parts very clean before soldering. Most solder has Rosin core and does not really need any paste.

That solder gun belongs in a museum along with the paste.......have to be 20 years old.....just a comment...not being critical.

[dicklague]

Also heat up the brass not just the wire. That will give you the strongest solder joint.

[gavinc69]

Just going to start the MSD install and removed the cover in the engine bay.
Was wondering what this black box is for (circled in RED in image 1)....Havent seem one in anybody else's engine bay shots!!!!

[Driver_X]

External Voltage Regulator.

[Walter_Middie]

[gavinc69]

Thanks. I'm taking it I need that then and can't remove it to make extra space?
The car did originally have air-con but its been taken out now, so if its for that I guess I could remove it.

[LakeCleElum]

I had the resistor fail a road trip once in my '73.5 when the battery pos. post made contact with a ground. I had a tow truck take my to a small town on a Sunday and started trouble shooting.....I wound the problem and fixed it with a spare piece of insulated wire, a pocket knife and a tube of liquid steel........I just used the liquid steel like solder and it got me back home across the state....

[gavinc69]

I've got a european driving trip coming up in June so I think i'll mod a few rotors and take a spare with me.....

[Walter_Middie]

Thanks. I'm taking it I need that then and can't remove it to make extra space?
The car did originally have air-con but its been taken out now, so if its for that I guess I could remove it.

It's part of the alternator and battery charging circuit. On older cars, the alternator provided juice to recharge the battery, and the external voltage regular determined how much voltage and when to apply it - like when you turn your headlights on, you need more voltage.

Most of the modern replacement alternators for your car have internal voltage regulators. If your car has been converted, you no longer need the external one on the engine compartment electrical panel. If your car hasn't been converted, you still need it.

Havent seem one in anybody else's engine bay shots!!!!

I still have one on my car - just like to keep it original if I can.

[gavinc69]

Ah right, thanks for the info....I would guess the alternator is original so I best leave it alone.

[dicklague]

Originally Posted by Walter_Middie

Thanks for the photo. I need to clean up my panel to install my new Daytona-Sensors CD-1 ignition. I am looking forward to testing all its features including programmable advance curve and data logging.

[gavinc69]

Just started the rotor modification and I have drilled out nearly all of the original Epoxy just leaving the fiddly end bits. But I have not found any sort of resistor! The rotors where purchased from Pelican part number 930-602-902-00-M14 and
Bosch model : 1 234 332 173-ou1
Is this already a resistor-less rotor that would work fine.
At work I did test the resistance on the rotor I have not touched yet and it read about 4.8, on the one I have drilled out it reported sort of 0.00 but the reading was flashing about for some reason. So is the epoxy working in place of a resistor or something?

[911pcars]

There's a solid conductor, off-the-shelf replacement ign.rotor for earlier Bosch distributors. Will that one work? If not, I thought there's was an equivalent rotor for later distributors as well. If not, ignore.

Sherwood