MSD Ignition question/concern

[MJHanna]

Originally Posted by RoninLB

Bosch 04038 from pelican

So what distributor does this rotor fit? 69-72? SC?

[RoninLB]

it fits my 1977

[Moke81]

When I opened this post I did not have any issues with the MSD. But I think I'm going to put the high vibration coil on, and Bosch rotor.
I was also thinking that maybe its the stock wire to the coil that can't handle MSD.
Where can I get a heavier coil wire?

Thank you
Barclay
_____________
1981SC Coupe

[Steve@Rennsport]

Barclay,

The reason you are experiencing burning is due to high resistance in the HV circuit.

Make absolutely certain that all of the ignition wires are completely seated on the plugs, cap, and coil terminals. You need a non-resistor rotor, as above.

I prefer the 8mm Magnecor ignition wires (although they can be tricky to get them seated properly in the cap) but any good quality 7mm wire will work as long as get properly installed.

I've been using MSD ignition components since 1978 without a problem,....

[VaSteve]

Originally Posted by snbush67

This rotor is manufactured in Mexico and purchased at a discount AP store that rhymes with Becker's.
After burning through about 7 million OEM rotors I tried this one and have had no issues, it is very sturdy.
As Al mentioned above the MSD kicks to much spark for the OEM rotor which frys the diode, once the circuit is fried the rotor shoots spark everywhere and can melt stuff.
This sturdier rotor puts the spark right where it needs to go and could probably handle a lightning strike or two.

For the archives....That looks like AC Delco #F403:
While we find your parts, please enter your ZIP Code at CSK Auto

[Howard M]

I'll tell you what makes me a little nervous about using the "ryhmes with Becker's" solid contact rotor. Look at the modest width of the contact at the tip, compared to the image of the Bosch rotor tip shown above. Remember that we have as much as 30 degrees of advance. Will the solid contact tip reach the distributor cap contact at full advance without requiring a very large spark jump, compared to the Bosch? I bought a solid contact rotor and I'm reluctant to use it for that reason. I think a better solution is to ream out the resistor on a Bosch rotor with a Dremel and solder in a jumper, as recommended many months and pages ago.

[VaSteve]

Interesting point. I couldn't find the solid one locally, so I'm going to mod my standard Bosch one. I think whatever is pictured by RoninLB is for a different year/kind of car.

I was buying a new rotor at the NAPA and got talking about what I was trying to do. The other counter guy overheard me and asked about what kind of German car I had. He said he makes/mods rotors for his hot rod dragster Beetle. He knew exactly what I was talking about.

[jstobo]

I don't think you need to worry about the width of the rotor tip. Remember the timing advances because the inside of the distributor moves as it spins. The distributor doesn't move, the cap doesn't move so the connections for the plugs stay in the same place. The plates inside the distributor though moves and it will only discharge the spark that is built up as the rotor gets close to a conductor ( the plug connector). If anything, the smaller tip will make the timing more accurate as it has to get closer to the conductor before discharging the spark. I have done the Dremel thing and it is a PIA. Buy a couple of solid rotors and save some time.

[Howard M]

jstobo, you've inspired me to think some more about my theory. You are correct, the rotor will fire at the same spot with respect to the distributor cap. At high RPM the internal distributor plates will move the rotor shaft to an advanced location with respect to the crankshaft...but the distributor cap contacts won't know the difference. So I CAN confidently use the "ryhmes with Beckers" rotor.

[VaSteve]

Hey Howard M, where'd you get that solid rotor? I just did the mod this evening on two rotors, my old melted one and a brand new one from NAPA. It was fun to twiddle in the garage, but I wouldn't want to make a practice of it. We don't have anything that rhymes with Deckers around here...are you referring to Checkers? Got a part number on that?

[snbush67]

I got mine at Checkers O'riley. I cant find the box and there is no part # I'm going to go look for the box again now.

[snbush67]

VA,

I couldnt find the box but It has to be the AC Delco part you mentioned above:

ACDelco Rotor, Distributor:

Part Number: F403


This product fits the following vehicles:

1978 Porsche 911
SC H6 3.0 Liter FI - VIN 2

1979 Porsche 911
SC H6 3.0 Liter FI - VIN 2

1980 Porsche 911
SC H6 3.0 Liter FI - SOHC

1981 Porsche 911
SC H6 3.0 Liter FI - VIN A

1982 Porsche 911
SC H6 3.0 Liter FI - VIN A

1983 Porsche 911
SC H6 3.0 Liter FI - VIN A

Shane

[Howard M]

My information is for a 1976 911S (stock 2.7L). I found the Checkers web site ("CSK") to be very informative. For me, the Borg Warner D555 was the correct rotor. Somewhat confusingly there is also a D555P available. I called BW and they explained that the "P" products are a cheaper version (cheaper than an already cheap plastic rotor??). There is no Checkers near me either, so I purchased D555 by mail. The Bosch resistor rotor is a much more substantial piece than the BW D555, but the BW unit has the full solid contact.

I have had no problems with my conventional Bosch resistor rotor after more than five years with the MSD, so despite MSD's recommendation to use a non-resistor rotor, a burned rotor is probably an indication of some other issue.

[prschmn]

Lots of good ideas for curing the problem here but feel compelled to throw out one more potential cause. Though the vacuum advance does not change rotor/cap alignment, the centrifigual does,you may want to check that.
Also possible that the vacuum unit has been changed and may not align correctly.

[prschmn]

Apologies. Seems ive having distributor dyslexia------Vacuum advance changes the relative position not the other way around. anyway dizzy indexing is important when running MSDs lest one busrn things up.

[snbush67]

Originally Posted by Howard M

I have had no problems with my conventional Bosch resistor rotor after more than five years with the MSD, so despite MSD's recommendation to use a non-resistor rotor, a burned rotor is probably an indication of some other issue.

I previously hadn't considered this point but you are right on target. This is a good point, the dozen or so rotors I had gone through were burnt because of the previous wires I had which arced really bad and were especially poor in the rain and that arcing is which I believe caused the rotor resistor to burn.

Now that I have changed to MSD wires I have had no problems with my rotor I just haven't changed back to the Bosch so I cant validate your point entirely.

Thanks, Shane

[RoninLB]

Originally Posted by prschmn

anyway dizzy indexing is important when running MSDs lest one busrn things up.

most excellent point although the Bosch dizzy doesn't seem to have major issues afai know



post the easiest method etc for the Bosch

thx




And my personal take on rpm rotors w/MSD is that it's a problem waiting to happen.
.. different strokes

[RoninLB]

Originally Posted by MJHanna

So what distributor does this rotor fit? 69-72? SC?

it fits mine

pelicanparts site will show which year span. Bosch dizzy, cap, & rotor is a great package.

[RoninLB]

I like blue








MSD 6M-2
pn 6460

it's one of those units that can operate while spinning and banging inside an operating washing machine


those MSD rubber mounting feet work great

[whiskyb]

I have the MSD-6 on my 2.7 When I went to buy a coil for it the counter guy said here this is the one you need. It was a MSD but I do not remember which one. Reading his book their was something about that coil, possibly ohm rating that did not agree with my MSD-6 or possibly my pertronix. They did have another coil that looked identical that was the correct one. I have looked through everything I have and cannot find what the issue was though.

I'll keep looking