Can someone clear up for me what exactly HEI is? From what little I know, it seems like a reasonable performance upgrade. Is it worth it or can it even be done on our /6's?

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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

HEI = High Energy Ignition.

The GM module people use on slant 6's has no performance advantage over the Mopar ECU other than it's smaller. It is just an electronic switch that controls the flow of current through the coil just like the mopar ECU.

The "High Energy" comes from the combination of parts and if you do not use the GM coil (or other aftermarket high output coil) the performance of the ignition will not be any different than an all Mopar electronic ignition.

It has been suggested by some that by using the HEI module you do not need a Ballast resistor. The need for a ballast resistor is determined by the design of the coil not the control module. If you continue to use a stock mopar coil you still need to use a ballast resistor.

NOTE: These statements do not apply to after market ignition systems like a MSD. These type of ignitions are a capacitive discharge design and operate on a different principle to the GM HEI and mopar electronic ignition.

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Dave Clement
68 Barracuda (Hot-Rod \6)
http://mysite.verizon.net/vze4pgxf/

So if I were to use say, an MSD Blaster2 coil with a GM type HEI distributor, I could ditch the ballast resistor AND the ECU?

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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

There is an outfit, Davis Unified Ingnitions, that makes a whole GM HEI system for some mopars. I do not know if they do it for a slant 6. It seems that that big GM cap with the coil in the top might have clearance issues on a slant.

If the MSD Blaster coil does not recomend the use of a ballast you could use it with the mopar ECU and get the same benefit as you would with the GM HEI ecu module.

Just keep in mind that points are just a switch that turns the current flow on an off in the coil. The Mopar ECU and the GM HEI module are just electronic switches that replace the points. You get a hotter spark with either one compared to a set of points because they switch faster which results in a hotter spark. The two modules are of the same basic design internally.

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Dave Clement
68 Barracuda (Hot-Rod \6)
http://mysite.verizon.net/vze4pgxf/

Just did some looking at HEI modules, and given the price, I can't see a real benefit of an HEI system over a high performance electronic ignition. Electronic it is

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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

There is a benefit not mentioned as of yet. IF you're planning the GM/EFI conversion to your slant, it might be wise to use the GM HEI module to control your ignition. This would allow the main GM processor to advance/retard your ignition, depending on whether you also incorporated the knock sensor in with your conversion.

Other postings are correct, however. You won't see any real performance improvement over the stock Mopar equipment

Roger