MSD 6245 digital replacement for 3 pin CDI open items

[HKZ Bob]

Hi Forum,
I purchased the MSD 6 AL digital 6245 for my vintage 911 form 72 which runs a Bosch CDI.

I do not want to make severe modifications. Can you answer my questions below and do me a wiring proposal.



BR
Bob

[304065]

Bob,

A=Achtung! = 450V output from CDI to coil
B= Batterie +12V from battery
C= contact = points
D= Ground/Erde (don't know why D- but that's what it is)

MSD
White= points trigger- connect this to CDI "C"
Orange = +450V output - connect this to CDI "A"
Black= to coil negative- I think this may be a floating ground so connect it to the coil directly.
Heavy red- +12V unswitched- this is direct current from the battery. The MSD will draw up to 10A so you don't want it going through a switch.
Small red- +12V switched from ignition.

This doesn't add much wiring and is easily removed. If it were me, I would remove all the CDI wiring and store it, no reason to use old, work-hardened, brittle wires when brand new is available.

Good luck!

[HKZ Bob]

Originally Posted by 304065

Bob,

A=Achtung! = 450V output from CDI to coil
B= Batterie +12V from battery
C= contact = points
D= Ground/Erde (don't know why D- but that's what it is)

MSD
White= points trigger- connect this to CDI "C"
Orange = +450V output - connect this to CDI "A"
Black= to coil negative- I think this may be a floating ground so connect it to the coil directly.
Heavy red- +12V unswitched- this is direct current from the battery. The MSD will draw up to 10A so you don't want it going through a switch.
Small red- +12V switched from ignition.

This doesn't add much wiring and is easily removed. If it were me, I would remove all the CDI wiring and store it, no reason to use old, work-hardened, brittle wires when brand new is available.

Good luck!

Thanks for your help, do you have also experience with the rpm meter.
(tach meter). I looked the tach signal up with the scope a nice 12V square signal with a 50/50% duty cycle.

Can I connect this signal with the VDO rpm meter. I have to connect this grey cable to the C of the CDI harness side.

I connect it to my test bench. This box is strong. Would you recommend to open up the spark plug gap to increase the break through voltage and increase the lenght of the spark.

BR
bob

Thanks

[304065]

Bob.

The VDO tach requires 11V square wave, duty cycle probably similar to the dwell (38%). The MSD box side terminal emits a 12V square wave with a 20% duty cycle. The modern 6al-2 emits 12V with a 25% duty cycle. Usually, in order to use this output, you must have your tacho board changed by North Hollywood Speedometer. This is what I did for my 10,000 rpm tach and it works beautifully and accurately.

Yes, for MSD you can use a 1mm spark gap, maybe as high as 1.27mm. The gap decreases with the compression ratio. For this voltage you MUST have good wires and cap and a non-resistor rotor. If you use a resistor rotor it will catch fire.

Good luck!

[HKZ Bob]

304065,

Sorry that I cannot name you name. You are a good man.

I have the new MSD 6AL digital. This unit might be different thant the old style.

I used my function generator as a input trigger. The interested thing is if I change my dwell angle ( duty cylce) of the function generator the output of the MSD tacho drives stay constand 50/50% duty cycle.


This might be different to the old untis.

To the finger, if it is pottet is has a resistor inside? I thought the resistor was in the wires for noise depression of high frequecies.





Danke
Bob

[304065]

Ignition Rotor Meltdown

[Eagledriver]

Bob,

I also have a 72 911 and use an MSD box. You can use most of your original wires. You'll need to use the orange and black wires for the coil. You cannot ground one side of the coil. I hook the heavy red wire up to the 20 amp fuse on the ignition mount plate in the engine bay. The switched red can use your old connection for the Bosch unit. My tach works fine with the MSD 6al.

-Andy

[HKZ Bob]

Hi andy & folks

can you name me the rotor Napa number for the 72 Bosch dizzy without the resistor.

BR
Bob

[Eagledriver]

I don't know the number for your car. I have a 3.0 engine now in my car. I'm pretty sure it's the same as a VW bug for your car.

-Andy

[HKZ Bob]

Hi I like to share some pictures of my installation.

First of all MSD has a new connector!

I made some inverstigation of the connector. it is a 12 pin Delphi Packhard GT 280/150 series device.

Four 2.8 mm terminals and eight 1,5 mm terminals.

Power Supply:

That unit may take 1 Amp per 1000rpm and with saefty max 10 Amps.

I am going to connect the power supply and ground to the stater cable.
So I have to route the power supply lines in shroud tubing at the rear wall to the starter motor.

Installation:

About the innstallation I choosed the new digital series which is very compact and fits in the original Bosch CDI spot with some changes on the board.






Bosch Finger for a early 72 Bosch Distributor still not solved yet.
BR
Bob

[304065]

Rotor Modification For High Output Ignition Systems

[HKZ Bob]

Thanks 304065,

I am struggelling with the correct part no of the Bosch rotor.

My rotorshaft has a diameter of 14.4mm and the rotor dia is about 35mm.
This is the data related to oem rotor bosch 1 234 332 206 cutoff at 7300 rpm.

Now there is a lot of information on this board. None of it is precise defining part no.
There is a call out for
04038 Bosch No. 1 234 332 215 with 1K resistor or
04033 Bosch no. 1 234 332 300 with 5K resistor aslo
also some VW no like 055 905 225B.

If you follow up on this link which is refering 04038 which calls out a 14mm shaft which won't fit. My shaft is 14.4mm.

VW/Audi Ignition Rotor 14mm, 055909225B, Bosch Auto Parts

Then there is this other seller in Germany who sells 055905225B and reports out the finger has 15mm diameter.



Same part no two different values. What is correct now.


eBay: Neue und gebrauchte Elektronikartikel, Autos, Kleidung, Sammlerst

VW Bus T3
Zündverteilerfinger
passend für T3 WBX
VW Ersatzteilnummer: 055905225B
Finger mit 15mm Innenmaß
NEU

[304065]

Bob,

According to Bosch, 215 = 5k Ohm widerstand
300 = 1k ohm widerstand
the fow-vay number you list is the same part as the 300

I would try the 300 and see if it burns up.

ORIGINAL BOSCH VERTEILERLÄUFER ZÜNDUNG ZÜNDVERTEILERLÄUFER NEU | eBay

14,4 is correct, I think the one who says 15,0 has measured incorrectly

[Turbo_pro]

Hi Bob
I believe that you can wire your MSD box for single discharge eliminating the need to modify the rotor.
We also mount the MSD box under the seat (driver or passenger) and place the coil where the original Bosch CD went. This does a couple of things. It take the CD unit away from the RF field generated by the plug wires (allowing you to use solid core wires), it removes the coil from the fan housing (isolating it from vibration) and by placing the CD unit under the seat you drastically enhance the engine compartment aesthetics.

[HKZ Bob]

Hi Jim,

Thank you for your comment. I have conneted the supply with the MSD harness to the positive terminal of the starter and ground. So I have a good power supply.

The coil is on the same position as the factory setup. I hope the blaster coil is as robust as the Bosch Coil.

I am using the original spark plug wires from Beru or Bosch. I do not know who is the supplier but I know the core is twisted copper.
Do you have bad exierience with the OEM spark plug wires.

Do you think the RF field from the wires are generating misfire events due to immunity issues of the MSD box.

I have not experienenced misfire on my test drives.
What kind of air gap did you run on your spark plugs and what rotor are you using?

BR
Bob

[HKZ Bob]

Hi Forum

I can now confirm that VW-Nr.055905225B &
Bosch-Nr.1 234 332 300 is the correct part no. It fit perfect to an early 72 911 Bosch distributor.

And if you buy the cheap version from VW-Bus.com you get a finger for 3.50 Euro
which is not a Bosch or Bremi and with no resistor in it.

They made it look like the Bosch but they potted a copper lead frame in it with no
resistor. I opened it and could confirm it.

Here the address of the shop

Oliver Krücke Nutzfahrzeuge
Oliver Krücke
Gewerbe Str. 5
16727 Oberkrämer OT Eichstädt
Deutschland Telefon: 03304 253368
Fax: 03304 253347
E-Mail: ebay@vw-bus.com

Thank you sharing my findings with you.

BR
Bob