My Challenger has the Rallye gauge package. It currently has the stock electronic ignition system and coil. I started to install an msd blaster 2 coil and a friend said it might damage the tachometer. Has anyone else heard of this? Thanks in advance.
MSD Blaster 2 Coil Question
- Thread starter ebodyman1
- Start date
Steve340
Well-Known Member
Tacho probably would not be worried by the coil but it may not be compatible and could damage the ignition box.
Xcudame
Well-Known Member
You cannot run an MSD Blaster coil with a stock Rallye gauge cluster! So your heard currently. I would just run a regular coil or ungrade to an MSD ignition. The problem is the new MSD boxes are cheap ChiCom crap that fail. Therefore just use a stock type coil. Preferably a coil made in the USA if possible! If you can find an MSD made before 2000, you're golden. You run to tachometer off the MSD box and not the coil.
Katfish
Well-Known Member
Never heard this before, why not?
Vaanth
Well-Known Member
If using an MSD coil in an otherwise stock Chrysler electronic ignition system, the tachometer is triggered from the negative (-) terminal of the coil the same as a stock coil. However, the MSD Blaster 2 series coils have a 0.7 ohm primary winding compared 1.4-1.8 ohm range of stock Chrysler coils. To use this coil with a stock electronic ignition system, use a 1.25 - 1.5 ohms primary ballast resistor instead of the 0.55 ohm primary resistor used with electronic ignition to mid 1975. Using the higher resistance resistor is to keep the primary circuit current at the same levels to prevent overdriving the switching transistor on the electronic control unit (ECU).
If using the original type four terminal, dual ballast resistor, the primary, or compensating, side should be 1.25 ohms. Original and early replacement dual ballast resistors had a 0.55 ohm primary side resistor (Chrysler part number 3656199). The primary resistors changed during 1975 to 1.25 ohms (Chrysler part number 3874767). Later Chrysler resistors and replacement units are typically 1.25 ohms, but should be checked for actual resistance.
If using a two terminal, single ballast resistor, ensure it is 1.25 - 1.5 ohms as well. Most replacement resistors nowadays are typically ~1.25 ohms, but it can vary.
A better match for the stock electronic ignition system if changing to an aftermarket coil is the Accel 8140 or 8140C:
| Accel | 8140 Super Stock 8140C Super Stock | 1.4 ohms | 9.20K ohms | 8140 = painted 8140C = Chrome |
I have used the Accel 8140 for the last 30+ years with my stock or mostly stock systems. All are old USA production. Like MSD and other brand offerings made overseas today, quality and reliability might be in question though.
The following table lists MSD Blaster coils:
| Part Number | Primary Resistance | Secondary Resistance | Notes | |
| MSD | 8200 | 0.7 ohm | 4.50K ohms | Chrome. |
| MSD | 8202 | 0.7 ohm | 4.50K ohms | Red. |
| MSD | 82023 | 0.7 ohm | 4.50K ohms | Blaster 2, black, |
| MSD | 8203 | 0.7 ohm | 4.50K ohms | Blaster 2, chrome. Supplied with a 0.8 ohm ballast resistor. |
| MSD | 8222 | 0.7 ohm | 4.70K ohms | Blaster 2, black, epoxy, high vibration, |
The following table shows original and aftermarket replacement resistors:
| Chrysler Number | Aftermarket Number | Terminals | Resistance | Notes |
| 2095501, 2196316, 2275590, 4106140 |
| 2 | 0.5 | Single, 1960 - 1972. Metal strap, although some later manufacture might be with a molded mounting hole. |
| 3656199 |
| 4 | 0.5/5 | Dual, 1971 - mid 1975 |
| 3874767 |
| 4 | 1.25/5 | Dual, Late 1975 - 1979 |
| 4106140, 5206436 |
| 2 | 1.25 | Single, 1979 - 1989 No metal strap. Some listings show 5206436 as 1.0 ohm. Others show it as 0.7 ohm. Actual measured value is 1.2 ohms. |
Manufacturers changed values and re-used some numbers. The table specifies the original ratings.
If changing the Chrysler electronic ignition to an MSD ignition controller system, the triggering for the tachometer is different. MSD is essentially a multi-spark ignition (at lower RPM) capacitive discharge system. It applies a higher voltage discharge to the coil. If a tachometer is connects to the coil negative terminal in this case it can be damaged from the higher voltage seen. MSD controllers provide a separate tachometer trigger that mimics the original style coil trigger signal.
For more information about the Chrysler electronic ignition system, including coils and ballast resistors, see the following:
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