Ok... Some background. So I had one past successful HEI conversion with an accel 35361 module and blaster SS coil (MSD's performance e-core design).

I've done another conversion using the same pieces to another car. I made a small plate (stainless, 16-18awg maybe?) with a 90 deg bend and mounted it where the alternator bracket previously was. Mounted the module to it with white heatsink grease, and the coil next to it. The hardware kit in the coil comes with rubber feet to isolate from vibration that I used also. Ran my own 18awg power wire to the ballast and jumped the connections together. Perhaps not the best, but was better then the previous successful install. That one, stock EI car, I relied on body ground through the heatsink (a more substantial 6x3x1/4" alu plate on the driver inner fender) and just ran small jumpers to the stock harness plug. The coil also connected to the stock harness.

It worked well for a couple weeks, then suddenly quit in the middle of a trip. Found the HEI module got so hot it was oozing some kind of fluid (no, it wasn't the white paste melting, something inside oozed out) - it got hot to the point the plastic melted a bit and discolored the yellow accel sticker.

This time I went for a Echlin TP45 module. Box said made in USA, yay. Used a similar heatsink as past successful install, 6x3x1/4" alu slab bolted to driver inner fender. This time I had to raise it 1/4" off the fender though as I used screws/nuts to hold module down instead of drilling/tapping the plate. Coil stayed on same bracket. Used the same coil - resistance tests were as published by msd. I know, resistance tests aren't foolproof but I figure if the windings didn't short together when the past module cooked it's probably ok. Bulletproof wiring - 12awg coil to module, battery to relay to module, module to battery ground. A mere 20mv drop (Yes, 0.020v) from battery post to coil + when revved in driveway.

So far so good, but it's only been a day. It's hot out... high of 100 give or take. The heatsink, after idling for many minutes, gets too hot to touch while the module is just warm.

So, long story short... how hot does your HEI heatsink get? I've read quite wildly varying accounts online from barely warm to similar descriptions of mine. I don't have the other car with the successful install anymore to compare. It seems the heatsink is doing it's job well. If I hadn't lost the other accel module I wouldn't be as paranoid as I am about the heatsink temp now.

Stainless is not a good heat sink, that is likely the problem.

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Dave

1977 d-200 crew cab ex-army pickup wants it's /6 back
1962 Valiant 2 door, 170, three on the tree
1972 d-100 parts truck
80 volare wagon now a parts car

I just did the hei install on my 78 van with a 318. I used a simple piece of 3/4" angle aluminum and mounted it to the boss on the valve cover that is intended for an emissions piece. . The trucks did not have it. I can post pics if you like

I did find it funny that the install would not work until I unplugged the Chrysler ei box.


Greg

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http://www.youtube.com/hyperpack

Sure, pics welcome.

The question is though, was your heatsink too hot to touch after driving for say 10+ minutes? I think my sink is on the large side, 6x3x1/4. I figure if mine is hot, everyone else's would be too unless something else was amiss.

I haven't measured temperatures on my HEI or its mount. I should have, having had access to thermal imagers for years ...

Heat sinks should have good thermal conductivity, and lots of surface area for convection and radiation. Mass is a good thing, but once the mass gets hot, we need to cool it with convection and radiation for steady-state operation.

Convection depends on a cooler fluid flowing around the sink. Delta T, area, and airspeed, in our case. Radiation depends on cooler surroundings.

Stainless steel is not nearly as good a conductor of heat as aluminum. In a shiny finish, neither has great emissivity (related to how it radiates - higher is better in this case).

For years I used the inner fender for my HEI "heat sink". I scraped the spot to bare metal and put a dab of heat sink compound between it and the back of the module. When the car is in motion, there is a lot of air moving around in the wheel wells. The only other part in there that might be hot would be the brakes, if you were driving hard. This worked without failure in many long drives during Texas summers.

A matte-finish finned aluminum heat sink is hard to beat for simplicity, and is what I'm using now. It's just a band-sawed and sanded hunk of some scrap I found. It is spaced from the inner fender to allow some airflow on the back side and to make sure any stray water stays away from the connections.

More elegant:

ACDelco Bracket

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

So I borrowed an IR thermometer gun. I was forced to learn about emissivity after getting some whacky readings on the heatsink. After putting a piece of electric tape on it, my too hot to touch heatsink was barely 115 degrees. I was expecting it to be more then double that.

These otta be able to take 200+F steady if they were originally put on distributors, so I'll be content that current temps are in the 1xx range. The stainless bracket the coil is still on wasn't much hotter though, maybe 120's I think, but that was without any heat load from the module.

$14.97 plus shipping is a hard price to beat for a nice bracket. If you have scrap and fabricating skills you can probably spend less. But for me, my time is worth more than the $15 asking price and anything I made would look much worse than that bracket.

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Casually looking for a Clifford hyperpak intake for cheap.

That AcDelco Bracket is a nice Piece!

Thanks for sharing.


Greg

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http://www.youtube.com/hyperpack

$11.57 at RockAuto. Summit will price match

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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

Summit price matches rock auto? Nice.

I had plenty of aluminum, couldn't justify spending any cash on a smaller heatsink. In fact knowing that the OEM heatsink was small is kind of how I justified making my original small bracket sink combo. It seems my fault was making it from stainless. Perhaps it would have worked fine had it been aluminum regardless of size.

Dale Carnegie had a story about that.

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

How's this for a heat sink? My coil and HEI unit mount to this, along with the relay powering it.
<img src="http://imagizer.imageshack.us/v2/150x100q90/136/heatsinkw.jpg" border="0">
<img src="http://imagizer.imageshack.us/v2/150x100q90/136/coilbracketfinished.jpg" border="0">

It's easy to fool oneself with an IR temp gun or even with an imager. The assorted materials and surface conditions of automotive components don't help. What often happens is that a low emissivity (IR-reflective) surface you're interested in acts as a mirror and shows you the temperature of something else - maybe the sky, maybe the exhaust manifold, maybe the goof holding the temp gun.

Electrical tape is good high-emissivity temporary reference, if it can stand the heat.

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"When you find a big kettle of crazy, it's best not to stir it." - Pointy-haired Boss

1964 Valiant V200, 225/Pushbutton 904
BBD, CAI, HEI, LBP, AC, AM/FM/USB, EIEIO

I ordered this exact part from Amazon. The day it arrived I found the one I got when I grabbed the bracket from the junk yard.

I tried to return it, and Amazon gave me my money back and told me to keep the part.

So now I have a shiny new heat sink for free.

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1975 Dodge D100 Utiline
Slant 6, Super Six, Weber 38, 727
Repair work in progress.

A HEI ignition module can draw up to 8 Amps in extreme conditions, and most of that is converted to heat, nominal 8x12V=96Watt, worst case 8x14.4V=115Watt. That is an awful lot of heat to dissipate from a small area. Computer chip heat sinks are good examples of adaptable (free) HEI heat sinks. It is also vital that a good heat paste is used, NOT dielectric grease! Some of the heat pastes from computer shops will break down in moist conditions, after all they are mostly made for use within the dry evironment of a computer. My Standard module came with a little heat paste 'pillow'. GM has paste for cars.

https://en.wikipedia.org/wiki/Thermal_grease

http://slantsix.org/forum/viewtopic.php?p=287733#287926

Olaf

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Aspenized