I have installed/removed my hei conversion several times, I can get it to start up great. I took it for a drive again today. Seems like once it warms up it dies as soon as there is a load put on the engine. Headlights, brake lights cause it to stall once it is warm. I did run a ground wire from the distributor body to the hei unit. One thing I did not do throughout this whole time is replace the coil, factory as far as I know. Could this be the culprit?

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Excuse me, does this smell like chloroform to you?

The factory coil is not a good match for HEI. See the HEI upgrade instructions for discussion on coils.

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

I'm still having occasional glitches with my HEI conversion too. One thing that seems consistent is that HEI really likes high voltage supply to the coil, and a coil with very low internal resistance (the MSD Blaster was a must for mine to run consistently at all). Mine had been running great for several months, then abruptly decided to cut out on the highway the other day. After a few short "glitches" it finally just flamed out. I felt like Jeff Burton getting back to pit road after blowing an engine at Talledega on Sunday (but without the flames) since I had to exit the freeway, get across 3 lanes, and into a parking lot... but I made it! At that point I switched back to the Mopar box (I have both mounted, and I just have to move the coil feed from one end of the ballast resistor to the other and move the 5-pin plug to switch between them) and drove on to work, but it pissed me off. After some digging, it looks like it may actually be my ignition *switch* that is causing enough voltage drop to annoy the HEI unit but not the Mopar box. New one on the way from NAPA as we speak. I could put the ignition circuit on a relay, but that strikes me as just adding another point of failure, so I'll replace the ignition switch and see how that goes.

So far, I'm not impressed with HEI as being much of an improvement, but I realize that it may just be finding existing weaknesses in those pieces of my 42-year-old wiring that are still being used. It will probably be fine once I get all of the questionable connections and wires eliminated.

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I have the HEI conversion on my 66 Valiant, and have had no problems with it. I am using a stock slant six electronic dist. The curve makes no difference, as it is all in before I am at my converter stall speed. A GP Sorenson EL-102 module (4 pin)($15.98) and a GC-408 ($21.98) "E" type coil for a Gm 4.3 liter V-6. Wired it up as per the diagrams on this site. I am haveing a problem with the top end power falling off, but don't think it is an ignition problem. It does not miss or break up, just stops pulling at about 6,000 rpm.

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Charrlie_S
65 Valiant 100 2dr post 170 turbo
66 Valiant Signet 170 nitrous
64 Valiant Signet
64 Valiant 4dr 170
64 Valiant 4dr 225

True, just think about where this module was designed to be,..... about 1 inch from the coil! (And a well-developed coil at that.)
I ran 14 gauge wire to everything, and it's working fine now. I suspect if your battery gets old, it'll show up in your HEI system.
As for the HEI working, It's like everything else: pro's and con's. After I finally gat the thing to work, it's great. The engine's occasional miss is gone. And the HEI creates a great, long spark.

Good luck!

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225 Cubic Inches of Iron-Head American Muscle

225 bored .040 /.100 off block, Schneider Cam 224@.050~ .480 lift - Stock valves, blended bowls, Offenhauser intake with 500 Edelbrock carb

Aside from a good ground, the HEI needs the + side supply to have enough capacity. It does not use that much overall wattage but has a high current demand for very short pulses in the cycle. It will only show as an average if you check it with an amp meter. The chevy power manuals, at least the old ones, pointed this out and gave a minimum wire size for the + side. I believe it was 14 gauge. I have not cracked one of those books in about twenty years.

Loose connections and too small feed wire can overheat the module and kill it.

It would not be a bad idea to use a relay and give the HEI it's own fuse with a direct feed off the battery or starter relay. Maybe even step up to a 12 gauge wire. A ground lead of 12 gauge that connects the module, body, alternator and/or battery and and any other important circuit is not a bad idea either. There can be a fair voltage drop thru the normal block / body ground system. A relay and good ground works wonders with headlights too. There is quite a voltage drop in long, skinny, stock harnesses.

That's very good info, and it might help explain why I never had any of the starting/running/driveability problems that have been reported when going to HEI: I had a couple of big spools of wire in the garage, one 12ga red and one 10ga green, and I used that wire for lots of projects, including my HEI module wire-ups! Not because it was 12 and 10 gauge, but because I had it lying around.
The alternator B+ also offers a convenient, clean (corrosion-free) source of line voltage.
Definitely! Sheetmetal grounds are marginally OK when new...and they don't improve with age.
Aw you're just saying that 'cause it's true!

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

Some times the cheap details really make the difference.

I have used the B+ terminal several times for things that need a good supply, I can only agree with you on that. That little terminal has the highest voltage of any 12 volt source in the car, assuming the alternator works!