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Old 08-26-2011, 02:16 AM   #1
kikkegek
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testing MSD 6420 and HEI ignition

hi guys,

I just got two second hand MSD 6420 modules and one of them is supposed to be broken.

I want to test them and watched the video on the MSD websiit, but this video shows an ignition using a seperate ignitioncoil.

what I would like to know is which wires do I need to connect to test the module.

As you might understand I want to connect the least possible wires, because one of them is broken.

hope you guys can help me.
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Old 08-26-2011, 09:42 AM   #2
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Re: testing MSD 6420 and HEI ignition

That unit is a 6AL, basically, a 6 series ignition box with a plug in chip rev limiter.

You can wire it two different ways, both outlined on the MSD web site.

First way isn't the best, triggers the unit from the HEI ignition module, through the MSD WHITE wire, as a point system will trigger it that way as well.

Second, best way, is ti use the MSD wire adapter for triggering from the HEI magnetic pickup to the two wire magnetic pickup plug on the unit. This eliminates the issues coils cause for HEI modules, by removing the HEI module from the build.

Both methods work, the second is the best to use.

As far as testing goes, simply grounding the white wire should get a spark out of the system, but, in both system connection methods, leave the magnetic trigger/HEI module disconnected from the system.

What usually kills these units are three fold, in order, bad to imminent failure:

Spark plug gaps too large. NO MATTER the application, leave the gap down to .045, NO MATTER WHO TELLS YOU DIFFERENT. EXCESSIVE GAP MURDERS MSD BOXES

Too high an operating voltage, as in regulator stuck in 19 volt mode. Too many vots is usually not a large problem, but will start failing the coil, see next reason.

COIL. The most aggravating and prevalent failure of MSD boxes, IS MSD AND OTHER COILS THAT HAVE LAYER SHORTED, ESPECIALLY THE EPOXY FILLED AND "HIGH VIBRATION" ONES. Once the layer shorting starts inside the coil, the resistance values of the coil change, radically as the coil gets sicker, and over loads/over heats the HEI or MSD module, to failure. For quite a long trime, MSD has had way, way too many failure issues with their oil filled Blaster line of coils, because they were made at Pro-Bobbin, in Mexico, and were defective up to 80 percent of production. Now, the Blaster coils are made in China, and I have heard that they have layer shorting issues, just not nearly as high a percentage as the Pro-bobbin/Mexico coils.

I realize you are "across the water" from the U.S., but, MSD can rebuild those units, and there are coils that can be obtained from here that work a lot better, and don't have the problems of the Blaster coils. I am sure someone here could act as an agent to obtain ans ship them to you.

Hope this helps.
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Old 08-26-2011, 10:10 AM   #3
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Re: testing MSD 6420 and HEI ignition

Here is a PDF file on the MSD ignition. To test the module you will need a good points ignition coil with a 12 volt battery and a coil wire. You shouldn't need a ballast resistor unless you're going to be using a points ignition system.

You will need adobe acrobat to view the file.
Refer to page 9 for the test wiring and instructions and refer to page 16 to connect to a 4 pin module HEI distributor.

http://www.msdignition.com/uploadedF...structions.pdf
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Old 08-26-2011, 02:07 PM   #4
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Re: testing MSD 6420 and HEI ignition

thanks guys. I already had the manual downloaded.

I was just hoping for an easier way to test,because this means a lot of hooking up with the risc of taking everything down, because I connected the dead-box...

thanks for the heads up on the coils and stuff...

the thing I dont understand is they mention that I need to take the "coil wire" of and then test the unit. But I dont have the loose coil. I have the coil integrated into the rotor-cover...see picture...what wire do I need to take of in my case?

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Old 08-26-2011, 05:22 PM   #5
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Re: testing MSD 6420 and HEI ignition

The reason for pulling the coil wire is to check for spark, since you cant do that with HEI you'll have to line up the rotor to one of the towers in the dist cap and use that spark plug wire which is lined up to the rotor to check for spark to ground.
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Old 08-26-2011, 08:41 PM   #6
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Re: testing MSD 6420 and HEI ignition

Point of correction and information. On this ignition box, the coil is fed by two wires from the ignition box itself, NOT from battery power, so, NO BALLAST RESISTOR IS NEEDED.

Those particular 6AL's will work on the small red voltage feed wire into them to turn the module on, from 6 to 16 volts, no resistor, resistor, doesn't matter, all the thing needs is a voltage between those two parameters, to turn itself on.

If I were checking the coil on the vehicle, I'd leave it on the cap, pull the cap, then use a 12 gauge copper stranded primary wire, with alligator clip on one end. Connect the alligator clip to the carbon post on the rotor side of the cap, with the coil n place, and connected, and the other end about 1/8th inch from a good engine ground, and then, spin the distributor. No need to pull the cap/coil apart to check the spark from the coil, and you don't have to align the rotor bar with any plug terminal to do the check, and it also tests the carbon post as well.
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Old 08-27-2011, 05:36 PM   #7
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Re: testing MSD 6420 and HEI ignition

Would also like to add that the MSD box, when triggered by its white wire, from a set of stock points, removes most of the current from the points, so, they don't have the contact face erosion/pitting issues that a regular ballast resisted system does. As we all are aware, the ballast resistor is in the stock points system to lower the line voltage and current, to reduce pitting of the point faces. The MSD system lowers the points current so much, that the pitting is virtually removed, and, except for point rubbing block wear, the points will live long and prosper far more than in the stock system, without the wear/retarding issues.
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Old 08-28-2011, 07:32 AM   #8
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Re: testing MSD 6420 and HEI ignition

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Originally Posted by HEI451 View Post
Would also like to add that the MSD box, when triggered by its white wire, from a set of stock points, removes most of the current from the points, so, they don't have the contact face erosion/pitting issues that a regular ballast resisted system does. As we all are aware, the ballast resistor is in the stock points system to lower the line voltage and current, to reduce pitting of the point faces. The MSD system lowers the points current so much, that the pitting is virtually removed, and, except for point rubbing block wear, the points will live long and prosper far more than in the stock system, without the wear/retarding issues.
thanks for the info...I'll report back when I have made progress...right now it rains like crazy over here and my garage is open air in front of the door...
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Old 08-28-2011, 01:26 PM   #9
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Re: testing MSD 6420 and HEI ignition

Bring it here, high desert, 80 miles south east of Reno, it'll be 106 today, and dry! But, come late November, we'll have 6 feet of snow, not as much as you lot get over there, but, SNOW, ICE, SLIDING ON THE ROADS, and a lot of people that just don't know how to drive on it. It makes for a really big destruction derby around here.

Let us know what you find with the tests, please.
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Old 08-28-2011, 01:39 PM   #10
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Re: testing MSD 6420 and HEI ignition

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Originally Posted by HEI451 View Post
Bring it here, high desert, 80 miles south east of Reno, it'll be 106 today, and dry! But, come late November, we'll have 6 feet of snow, not as much as you lot get over there, but, SNOW, ICE, SLIDING ON THE ROADS, and a lot of people that just don't know how to drive on it. It makes for a really big destruction derby around here.

Let us know what you find with the tests, please.
last two winters here had some pretty bad times too....this was after one week of not driving my Audi during christmas holiday last year:



at least it is not 6 feet...hahahaha
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Old 08-29-2011, 08:52 AM   #11
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Re: testing MSD 6420 and HEI ignition

a friend pointed me to this procedure:

http://techwest.ipower.com/page2.html

anybody ever tried that yet?
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Old 08-29-2011, 11:14 AM   #12
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Re: testing MSD 6420 and HEI ignition

I am doing a 1964 C30 1 ton dually flatbed as a custom vintage service truck right now, and about two weeks ago, one of my across the street neighbor's pals gave me a really nice hydraulically actuated snow plow for my truck. Of course, I will more than likely be required to plow ALL the streets around here, for everybody, on my gasoline dime for getting the plow for free, but, what the heck, the price was right. All I need to find next is a free snow blower attachment I can install to blow the plowed show away from the side of the road, and I'd be stylin'.
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Old 08-29-2011, 02:46 PM   #13
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Re: testing MSD 6420 and HEI ignition

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Originally Posted by HEI451 View Post
I am doing a 1964 C30 1 ton dually flatbed as a custom vintage service truck right now, and about two weeks ago, one of my across the street neighbor's pals gave me a really nice hydraulically actuated snow plow for my truck. Of course, I will more than likely be required to plow ALL the streets around here, for everybody, on my gasoline dime for getting the plow for free, but, what the heck, the price was right. All I need to find next is a free snow blower attachment I can install to blow the plowed show away from the side of the road, and I'd be stylin'.
okay! now we are really gettin off topic! hahahaha
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Old 09-01-2011, 02:21 PM   #14
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Re: testing MSD 6420 and HEI ignition

Quote:
Originally Posted by kikkegek View Post
a friend pointed me to this procedure:

http://techwest.ipower.com/page2.html

anybody ever tried that yet?
today I tested the two boxes and hooked up the multimeter too them.

and indeed...only one of them showed a connection and the other one stayed at 0 Ohm...

So I am trying the one that gave me a 0 kOhm connection first...because it said that a damaged unit will give you a reading of under 3 kOhm and indeed on of them gave me a reading of 1,5 kOhm
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Old 10-15-2011, 03:18 PM   #15
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Re: testing MSD 6420 and HEI ignition

installed the MSD 6420.

for some reason now the engine is running very rough. After start will idle for just a couple of seconds and then die. I can absolutely not drive it.

any ideas guys?
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Old 10-16-2011, 08:01 AM   #16
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Re: testing MSD 6420 and HEI ignition

check all connections last night. I had the Magnetic Pickup reversed. changed it this morning and now its running fine.

we'll see what it brings...
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Old 10-16-2011, 03:04 PM   #17
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Re: testing MSD 6420 and HEI ignition

Either reversing the wires or the magnet in the MSD/Ford pickups changes the timing and rotor phase between 25 and 30 degrees. Oddly enough, changing both the wire polarity AND magnet polarity only changes the timing and rotor phase about 20 crankshaft degrees.

Nice to hear you got it dialed in.
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