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Old 01-19-2021, 03:08 PM   #26
JohnMc
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I have an MSD 6A box on my PV's motor. And the wire I have it wired up, at least, it's easy to bypass (just remove the MSD output wires from the coil, take the inputs off the MSD and hook them to the coil, done), so you can easily do back-to-back comparisons. And it makes a noticeable difference. I used to think spark ignition was graded on a pass/fail curve. It either lights off the fuel/air, or it doesn't. And if it does - not much of a difference between 'barely' ignited and 'lightning bolt explosion happened' ignited.

But that's apparently not the case. With the MSD disabled, it's certainly not missing or misfiring, but with it working the engine starts noticeably easier, has noticeably more pep, especially at lower RPM's. Just feels somehow a bit crisper. How and why? Don't know. In addition to creating a much more powerful spark, MSD also produces multiple sparks at lower RPM's (MED = Multiple Spark Discharge) - so perhaps that does something as well. A crackle instead of just one snap?
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Old 01-19-2021, 04:31 PM   #27
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Is there any particular way to check the condition of the coil I have in the car?

I am going to do some reading on the MSD 6A box.

As far as I can tell the MSD box works alongside the existing distributor (points or pertronix) and an aftermarket coil. I could also just go with the 123 system which would get more multiple timing curves to play with. Or just slap a pertronix unit on the distributor, put in a hot coil, and call it a day.
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Old 01-19-2021, 04:54 PM   #28
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Yeah, it just sits between whatever ignition system you have and the coil. You can run them from a points dist, or any of the aftermarket ignition systems. The wires that went to the coil get hooked to the MSD, and it now runs the coil.

I'm using it with a Crane optical ignition system. And an MSD Blaster coil. Just those two by themselves produce much stronger sparks. the MSD just amplifies it (and multiplies it too, I guess). Probably stronger than it needs to be really. I've burned a hole through the top of the rotor before.

Back when it had the original firewall mounted armored cable coil, you could pull the coil wire and set it 1/8" away from something metal, and crank the motor. And it would make thin, wispy looking blue sparks. Zip, zip, zip. Now it makes big fat nasty looking red sparks. ZZAP, ZZZAP, ZZAP. The sort of thing that make s you think it would *really* hurt if it got you.
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Old 01-19-2021, 04:56 PM   #29
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It's not quite as easy to measure the primary on those coils but if you measure from the ignition switch to the distributor that would give you primary impedance. For the secondary you would measure from the switch to the coil tower. There are probably specs in the green book. You could also get a high voltage probe and measure the secondary voltage if the meter has a fast enough sample rate.
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Old 01-19-2021, 06:17 PM   #30
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Any recommendations for a decent coil to run with a pertronix or 123 setup?
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Old 01-19-2021, 06:50 PM   #31
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The old classic Bosch blue coil works very well. You don't need a ballast resistor for those so it's easier to wire in. There are probably Asian made fakes out there for the Bosch. So beware of that. I think Bosch makes them in Brazil now, possibly Spain, or Mexico.
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Old 01-19-2021, 09:41 PM   #32
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Quote:
Originally Posted by dl242gt View Post
The old classic Bosch blue coil works very well. You don't need a ballast resistor for those so it's easier to wire in. There are probably Asian made fakes out there for the Bosch. So beware of that. I think Bosch makes them in Brazil now, possibly Spain, or Mexico.
That is the one I was looking at.
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Old 01-19-2021, 09:58 PM   #33
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I'd recommend a real Bosch Blue (3 Ohm resistance) from a reliable aircooled shop. I was running one for a few weeks and had no issues, but with the MSD I'd suggest a non-internally resisted coil. I'm using a stock Bosch black coil from a 1990 VW Golf, but I think the stock fuel injected volvo coil would work too. They're wound pretty tightly so put out a hell of a spark . Something with a 1-1.5 Ohm internal resistance would give you the best bang for the buck.
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Old 01-19-2021, 10:20 PM   #34
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123 Ignitions recommends the Bosch Red (1.8 Ohm) coil for 6 and 8 cylinder applications so you know it'll be compatible if you go with a 123 distributor.

https://123ignitionusa.com/bosch-red...-resin-filled/
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Old 01-20-2021, 01:21 PM   #35
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So would it be worth it to go with the red coil over the blue coil or is that just overkill?
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Old 01-20-2021, 01:24 PM   #36
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The blue coil is the recommended replacement for the stock coil. The red one is considered a performance coil.
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Old 01-20-2021, 07:10 PM   #37
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Quote:
Originally Posted by hiperfauto View Post
The blue coil is the recommended replacement for the stock coil. The red one is considered a performance coil.
I've got a lead on a good condition red coil for a decent price. Would it make sense to just to jump on that and upgrade it while saving up for a 123 or pertronix unit?

I am aware that with some setups I would need a ballast resistor.

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Old 01-20-2021, 07:57 PM   #38
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It couldn't hurt. It's a common upgrade for the ACVW crowd.
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Old 01-20-2021, 08:45 PM   #39
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Make sure you buy a high quality ballast resistor. Like an OEM one. I ended up using two of the stock 240 ones in series. They are each .9 ohms and you need 1.8 for those coils. So two in series give you that value. At first I tried an Accel one which burned up with all the heat from the current.

When I did this on my 240 turbo I ended up going back to the stock setup. The red coil didn't run as well and then I noticed it leaking. So, that was the end of using the red coil.
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Old 01-20-2021, 10:08 PM   #40
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Quote:
Originally Posted by dl242gt View Post
Make sure you buy a high quality ballast resistor. Like an OEM one. I ended up using two of the stock 240 ones in series. They are each .9 ohms and you need 1.8 for those coils. So two in series give you that value. At first I tried an Accel one which burned up with all the heat from the current.

When I did this on my 240 turbo I ended up going back to the stock setup. The red coil didn't run as well and then I noticed it leaking. So, that was the end of using the red coil.
It would appear that Bosch made 1.8 ohm ballast resistors. Part number 0 227 901 014. From what I've read it is supposed to go with the red coil and were used on Mercedes.

Last edited by spock345; 01-20-2021 at 10:13 PM..
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Old 01-21-2021, 10:46 AM   #41
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FYI, the stock fuel injected Volvo 2.2/2.4 coils were ~1.0-1.5 ohm, epoxy potted (so they can be mounted in any direction) and are perfect for an MSD setup. That's essentially what I'm using and I don't get spark blowout at all, even with a .045" plug gap. The idle is amazing. I only say that to save you some money if you happen to have an LH2.2 or 2.4 coil lying around.

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Old 01-21-2021, 12:59 PM   #42
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Quote:
Originally Posted by Broke4speed View Post
FYI, the stock fuel injected Volvo 2.2/2.4 coils were ~1.0-1.5 ohm, epoxy potted (so they can be mounted in any direction) and are perfect for an MSD setup. That's essentially what I'm using and I don't get spark blowout at all, even with a .045" plug gap. The idle is amazing. I only say that to save you some money if you happen to have an LH2.2 or 2.4 coil lying around.
I do have an LH 2.4 coil sitting in my basement.
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Old 01-21-2021, 02:11 PM   #43
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That is a good way to go with the LH2.4 coil on the MSD. The red coil was laying around from when I had all my VW stuff. So, I tried it out unsuccessfully on the 240 turbo. After about an hour of running. Oil was bubbling out of the coil right next to one of the terminals. I chalked it up to a bad coil as there wasn't any issue with wiring or ballast.
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Old 01-21-2021, 03:53 PM   #44
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Quote:
Originally Posted by dl242gt View Post
That is a good way to go with the LH2.4 coil on the MSD. The red coil was laying around from when I had all my VW stuff. So, I tried it out unsuccessfully on the 240 turbo. After about an hour of running. Oil was bubbling out of the coil right next to one of the terminals. I chalked it up to a bad coil as there wasn't any issue with wiring or ballast.
I'll still probably pick up that ballast resistor so I can get to the 3 ohms that pertronix and similar systems specify until I can get a fully electronic system or MSD up and running.

I measured the primary and secondary resistance on the coil. Even accounting for some resistance along the wire in the armored cable and the switch the resistance for both seems higher than it should be. So any coil that is still within spec would probably be an improvement.

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Old 01-23-2021, 11:49 PM   #45
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The rough idle was a weak coil.
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