So, getting conflicting info on the use of the MSD Blaster 2 coil in an HEI swap without using a ballast resistor. MSD's instructions online are limited to say the least. Makes it look like that unless you are using an MSD box that you need to use their .8 ohm ballast resistor on the coil. They give the install with one of their boxes and then list install with the resistor for points and stock distributor systems.

Now, reading the HEI post here, if I understand correctly, the GM HEI module actually is sort of doing the job of a ballast resistor by regulating the voltage to the coil at different rpms.

So, if that is the issue then when doing the conversion to HEI with the Blaster 2 then purchase of their .8 ohm resistor is not needed and all should be fine. Is that correct or have I got it mixed?

Just don't want to toast a coil and have an issue with the car quitting.


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Put a line here as this is related, but off on a different tangent a bit.

Just checked the voltage readings on the car to see what was happening. All measurements using a Micronta digital multimeter.

Battery voltage baseline 12.77

Start car, warm, tacho steady at 750.
Charge rate at battery showing 14.6 to 15.05 fluctuating.
at 3500 rpm charge rate steady +/- .01 at a rate of 15.32

Voltage measured at module B termainal.
idle - 13.7 to 14.6 fluctuating
3000 rpm - 13.1 to 13.9 fluctuating

Voltage measured at + terminal on Blaster 2 coil
idle - 13.7 to 14.6 fluctuating
2000 rpm - 9.xx (wrote this down as an after thought and don't have exact 9 volt number.)
3000 rpm - 8.7 not much fluctuation at all, pretty steady.

Car has had the amp gauge modification done. As a note, the voltage regulator is chrome. Probably makes my car 3 seconds faster in the quarter , but wonder if it is some different value regulator? Had a blue one years ago that was a fixed 13.5 or something as I remember.

Concerned about the fluctuation in reading also. May be an issue of the multimeter sensitivity perhaps. Oh, and alternator is a swapped on high amp (80 I believe) off of the '73 Dart 318 parts car I had.

Thoughts?
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Next section. Story of quality perhaps. Swapped on a Wells regulator I had spare. Was not a new one granted. Came off a '73 parts car I had at one time.
Module at idle 12.94 - 13.19
Coil at idle 13.08 - 13.22
Module at 2000 rpm 14.03 fairly steady
Coil measured the same.

Head scratching time. Now have a tacho bounce like a miss on a plug. Check wires, all are on good, look at connections, all look fine. Tacho shows a definite dead miss type bounce. Stop car, pull wells regulator and put chrome one that was on the car back on, tacho now reads rock steady.

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From Mopars to classic Minis and back to Mopars in 19 years flat!

Will work for roast chicken crisps!!

To answer your first question, I have an HEI system and use an MSD Blaster 2 coil, and I can verify that you do not need a ballast resistor for it. It runs beautifully with full battery voltage, and I've eliminated my ballast resistor completely.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Thanks for the reply.

Does your voltage stay rock solid with a digi meter or does it fluctuate the same as mine does?

How long as your HEI system been up and running with no ballast?

Thanks for the posts!

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From Mopars to classic Minis and back to Mopars in 19 years flat!

Will work for roast chicken crisps!!

No ballast is used with the Blaster-2 coil with HEI. That's how my HEI systems have been configured and run for many years and many miles.

You will want to pay careful attention to your voltage supply. Feed the module with relatively large-gauge wire, preferably via a relay, and make sure your charging system is in top nick.

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一期一会
Too many people who were born on third base actually believe they've hit a triple.

My voltage at the battery fluctuates slightly when the engine is idling, and smooths out as I accelerate. I think this may be due to the older design of alternator that's on there now (OEM spec 35 amp). Once I take care of some more pressing maintenance on my truck, I'll get back to the Duster and convert over to a newer style alternator.

I've been using an HEI setup since shortly after I bought the car in April of last year. The factory Mopar ECU took a dump while I was tuning the engine the first weekend that I had it and I ended up having to do a quick install so I could get the car home, then clean everything up later.

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'74 Duster w/ HEI ignition, beat to snot suspension, A904, 8.25" 3.55 SG rear, still being tuned up and gets 17 MPG

Know how they always build a better idiot? That's me

Thanks for the replies! All looks okay then.

How about that Wells part eh? Just goes to show what the voltage regulator can do.

Cheers

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From Mopars to classic Minis and back to Mopars in 19 years flat!

Will work for roast chicken crisps!!