My 1973.5 911t came to me with an MSD 6A igntion system using the standard, stock black coil, installed by the previous owner. I have read that you should use an MSD Blaster coil with the MSD ignition. What sort of problems might be caused by using the stock coil with the MSD ignition? Thanks.
Peter________________________
1973.5 Black 911T Coupe
1988 Grand Prix White Carrera Targa
Early 911S Registry Member #686
I have not heard of any issues using the stock coil? I run that set up in my 3.0
Cheers
John
911 1967S 308470
[B]911 1965 301946 Irish Green
[B]911 1965 302962 Polo Red
911 1965 300760 White SOLD
911 1971S S/T 2.5
914-6 1970 GT 2.3
Look for me at a track near you!
Early S Reg #2699
https://www.facebook.com/#!/MachineMotorsports
I believe MSD recommends their coil, I believe the winding ratios are different. It's not a case of whether the car runs, but rather are you getting the optimum voltage at the spark plugs.
Early S Registry member #90
R Gruppe member #138
Fort Worth Tx.
+1... I run the MSD blaster coil with my MSD.Originally Posted by edmayo
I have had two blasters fail on me...no issues yet with stock. I can understand running the MSD
but I think the difference would be minimal
911 1967S 308470
[B]911 1965 301946 Irish Green
[B]911 1965 302962 Polo Red
911 1965 300760 White SOLD
911 1971S S/T 2.5
914-6 1970 GT 2.3
Look for me at a track near you!
Early S Reg #2699
https://www.facebook.com/#!/MachineMotorsports
As I outline in the thread below, the MSD HVB coil has primary inductance of 8.0mH. The Bosch CDI coil has inductance of 1.8mH. These are my own data measured with an inductance meter.
http://www.early911sregistry.org/for...d-NOS-SWB-Coil
Inductance is the measure of how the change in current flowing through a conductor induces a voltage in itself and nearby conductors. All things being equal, more inductance in a circuit will generate a greater magnetic field. It is this magnetic field that induces a current in the secondary windings of the coil to generate the spark.
The magnetic field also takes TIME to build up and to decay.
If you study the table of coils in my thread above, one thing that becomes obvious is that the Bosch coils that are intended to be used with inductive ignition have a high inductance. Compare, for example, the Bosch Blue coil to the CDI coil. This is because inductive ignition systems (like Kettering, and Motronic onward for Porsche) use the COIL to generate ignition energy.
A CDI system, like the Bosch BHKZ or the MSD, creates ignition energy by charging a capacitor with high voltage, then uses the coil as a step-up transformer. The coil is not designed to store energy. . . you can see this in the low inductance reading.
Now along comes the MSD 6A box-- designed to work with their blaster coil. The fact that their coil has higher inductance suggests that they are using the coil to store ignition energy to get the performance their engineers want. If you look at their web page, they also offer a series of E-core coils (no longer cylindrical but wound around an iron core shaped like the letter "E") and these have LOWER inductance, around 1 mH. They are only designed to be used with the Series 7 boxes, a later, more powerful design.
This is a long, but hopefully fact-based, way of saying that with your 6AL box you should use a blaster coil (take the chrome sticker off the side for cool points). You should also mount it securely to something that will be an adequate heat sink, ensure there is a good fit between the high voltage boot and the tower, use good wiring between the 6AL box and the coil itself and follow all the instructions to the letter. I've used these coils for a decade with no failures.
1966 911 #304065 Irischgruen
What about using the MSD Blaster coil with stock 1978 SC ignition system?
1969 911S Targa
1970 911S Coupe
1973 911T w 3.2
1972 Alfa GTV 2000
Same answer, it's a mismatch.
1966 911 #304065 Irischgruen
Just to add if its not already been said .... for the MSD ignition with the blaster ...... spark plug gap will have to be increased from 0.020/0.024" to 0.045" because of the voltage increase.
And below 3000rpm or so the MSD puts out multi sparks. (Timing light has to be compatible)
I'm using Clewett Engineering wires without any issues.
Daniel
73 Sporto 911T-V RoW
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