TreeSeeker
San Diego
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There are two fins already on it. That is what the wide u-shaped aluminum piece on the outside is for. Granted is should have more fins. I have seen at least one of the high-end units with lots more fins.
Maybe a 12v computer fan could be mounted over it.
The Pentium heat sink is also a good idea. Don't forget to use thermal paste.
This is why we should always carry a spare unit. RVs are often driven to very remote places.
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TreeSeeker
San Diego
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While I was working under the hood I was reminded of the water runoff onto the battery issue. Has anyone noticed that the hood seam is right above the battery? Every time I open the hood I notice water/dirt spots on the top of the battery. This was a very poor design. Most newer cars have a U-shaped seam so the U-shape carries the water away. Ours doesn't--dumps it right onto the battery. This is just asking for trouble.
Also the wiring harness is attached right to the edge of the seam. All the runoff also goes onto the wiring harness.
The best battery solution I can think of is using a marine battery box with a cover. This will require a lot of rewiring of the battery cables so they can be routed down to fit under the battery cover. Also, I don't know if there is enough clearance. I will have to get a battery box to see if it will even fit in there.
Anyone have any other ideas?
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Griff in Fairbanks
AK
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Joined: 04/21/2005
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eyeteeth wrote:Well then... mine would be the third. Mine is in better condition than TreeSeekers, components are still covered. But it still melted out.
I must be very, very lucky.
It's my impression ICMs get their negative/ground connection through the wires. I could be wrong. I may go out, pull the ICM from the parts donor Dakota, and look at the printed circuit board (PCB) inside. Specifically, I'll look at how PCB is mounted to see if any of the PCB's 'traces' lead to the metal case.
I may have fallen prey to a common cause of misunderstanding. Motor vehicle wiring diagram almost always just show the positive side of the circuit, without so much as a single ground symbol.
I do know heat is a big issue with ICMs, due to seeing it pop up repeatedly in things I've read. VintageMopar is correct, that big transistor generates most of the heat. Especially when it's cycling/switching 25-50 times per second. That's why it's mounted on the ICM's surface.
Paint is both an electrical and thermal insulator. So, I'd avoid any ICMs that are painted.
ICMs that don't specifically have heat sinks may be okay for normal operation. Less than ideal circumstances would make them iffy.
Aluminum is a reasonably good heat conductor. Copper is much better, approaching ideal, but more expensive. This is why most heat sinks are aluminum. Of the three metals, steel (which is mostly iron) is least effective, tending to hold heat rather than dissipate it.
(Think copper versus aluminum versus steel and cast iron cookware. Less expensive pots and pans tend to be aluminum. Advertisers stress copper in their coolware because it conducts heat better. Cast iron skillets and dutch ovens work because they hold heat.)
Surface area is important in terms of dissipating. So, finned heat sinks are more effective, with the more fins the better.
So, the ICM TreeSeeker found, specifically mentioning copper heat sinks, leads me to believe it is comparatively good. 'Weld' is probably a misnomer ... copper is almost impossible to weld because of how well it conducts heat. (That's why alloys with high copper content tend to be brazed or soldered.) Regardless, welded/brazed/soldered heat sinks are better able to draw heat away from components ... so, another indication of quality.
('Laser' tends to be an advertising buzzword. However, laser etching, versus tradition photo-chemical etching, leads to better quality assurance in mass produced printed circuit boards.)
Assuming I was mistaken and ICMs do need/use a chassis ground, loose/faulty mounting would add to the heat problem through unacceptable electrical resistance to ground. (Electrical resistance equals heat.) In this case, I'd be inclined to add a dedicated ground wire rather than rely on common chassis ground.
1970 Explorer Class A on a 1969 Dodge M300 chassis with 318 cu. in. (split year)
1972 Executive Class A on a Dodge M375 chassis with 413 cu. in.
1973 Explorer Class A on a Dodge RM350 (R4) chassis with 318 engine & tranny from 1970 Explorer Class A
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Griff in Fairbanks
AK
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BTW - the main purpose of painting, anodizing, plating, and phosphate treatment is to impede corrosion. Painting is cheapest ... and most likely to cause issues when it comes to conducting electricity and heat.
Anodizing and plating does little to impede the flow of electricity and heat. Standards and best-practices for marine low voltage (12-48 volts) direct current circuits is tin-plated copper wires.
I'm not sure about phosphate treatment. Next time I'm doing phosphate treatment, I'll do an experiment to see how much it insulates, if at all. (If I remember.)
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Griff in Fairbanks
AK
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TreeSeeker - I wouldn't get wrapped around five versus four pin ICMs.
Five pin ICM is the original variant, back in the early to mid seventies. Mopar then went to the four pin variant and used that for a much, much longer period of production.
So, four pin ICMs are more common and more readily available. Five pin replacements are relatively rare, due to a far smaller demand. They may also be more expensive, due to economy of scale.
There's also reason to believe Mopar made internal improvements when they went from five to four pin versions.
Changing over is easy, based on the volume of literature and guidance, as well as the apparently large number of people who have done so.
One route is to also change to the two-connector ballast resistor. That involves simply snipping off the fifth wire at the ICM connector.
Identifying which wire to cut is straight forward, using any of the many consistent diagrams on the web. (I posted a link to a pdf having one such diagram.)
The other route is to stay with the four-connector ballast resistor. In that case, the fifth wire is tied to one of the other wires. (Again, which ones to tie together is clearly diagrammed in multiple places on the web.) I'd probably just cut off the fifth wire at the ICM and jumper across terminals on the ballast resistor.
So, you're probably going to spend more time (days versus minutes) finding a five pin ballast resistor. I'd also bet what appears to be a five pin, in the sales literature, actually turns out to be a four pin. (In other words, they may be using an old five pin image to sell a four pin ICM.)
In any case, I'm done ... do whatever you think is best for you.
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Griff in Fairbanks
AK
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One final comment ... a computer fan wouldn't hurt but might not last due to being exposed to the elements. An inexpensive marine bilge blower would be better and last longer.
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TreeSeeker
San Diego
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Here is a link to a heatsink that I think will work. The distance between the two fins on my current ICM is 50mm and the heatsink is 50mm so it may press fit or it may require some filing. But it's cheap--2 for $3.75.
50mm aluminum heatsink
It doesn't say that it comes with thermal paste so you better order some of that too.
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TreeSeeker
San Diego
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Griff,
Just FYI, according to this graphic the case is ground.
I am still evaluating all options...
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j-d
Sunny Florida USA
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Joined: 09/04/2003
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We had a 1971 Dodge B300 till 1992 and ran it about 140000 miles. The 71 318 had points and condenser. Somewhere along the line, I replaced with a solid state distributor, MoPar module, and 4 pin ballast. It worked well. I think I had both black painted and plated modules. I remember the firewall stripping out where the module mounted. Can't remember if the ignition change was before or after I swapped the 318 for a 360...
But if I was to work ignition today, I'd use a GM HEI Module, with heat sink and home made wiring harness. gOOgle "chrysler ignition module to delco" for details. Several articles.
+
If God's Your Co-Pilot Move Over, jd
2003 Jayco Escapade 31A on 2002 Ford E450 V10 4R100 218" WB
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TreeSeeker
San Diego
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I found a great little YouTube series on Ballasted Ignition Systems. It is a series of 4 short videos each from 2-5 minutes. I found it very helpful in understanding these systems.
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