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Coil Pack


Richard S
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Was wondering if the coil pack on the 90 is similar to the large unit used on Grand Nationals or a multiple. Reason I ask is I was assessing what it would cost to install an MSD system, which requires 2 tack adapters and coil interfaces. Not clear whether it uses the single interface sold for the GN, or takes 3 separate interfaces?

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Guest Buick Mike

If I'm remembering correctly what the coil pack on the GN looks like, the Reatta's is similiar to that. It is one unit that sits on the ICM. I don't know what a "multiple" is.<P>I am a bit curious as to why you want to put an MSD on the Reatta, though...<P>Mike

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Friend of mine has an MSD [pn 6515] surplused form a Ford that even uses same tach adapters. Would not take it just to put in garage, so just thought I would install to see if it cured a couple of minor ills [slightly rough idle] and improved mileage at all. Only thing I need to make it work on the Reatta is the right coil interfaces. MSD seems to think it takes 3 interface units; I think it takes only the one they claim fits the Grand National. Want to find out who is right.

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I wondered the same thing? I have the MSD wiring diagram book and they have a block for the GN's that goes between the coil and module, but they state is for the 86-87 engines only. This is designed for their DIS-4 system. They also have the Stacker ignition module which adds to the stock ignition. This supposedly adds capacitive and multiple spark capabilty to the stock inductive system. It looks like it boosts the voltage to the coil to produce a stronger spark, but at the rpms's our engines are capable of, I wonder about the need for the stronger spark. The multiple spark at low rpms is supposed to give a smoother idle and low speed but I have no personal experience to judge. I must admit I wonder how this will help unless a cylinder has a misfire problem that a multiple chance to fire will help? As far as I know, the only advantage to the three separate coil blocks is the ability to change one instead of the whole thing, but no claims of stronger spark. Maybe Padgett has an insight?? confused.gif" border="0

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Your second post came in while I wrote my first. Is the part number actually 6215? I cannot find a 6515 in the catalog and it is only a few months old. The 6215 is the DIS-4 module which looks to have a single connector and the wiring diagram indicates the stock wires between the module and coils are cut and the harness to the DIS-4 module is spliced in between (butt connectors are shown). I could fax the diagram to you if would e-mail a fax number. Use the address in the signature if you want this off the forum. smile.gif" border="0

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Hal, I will quote the reply I got from MSD when I asked them what would be needed to adapt this unit from Ford to the Reatta:<BR>"We offer the MSD DIS4 PN# 6215 for the Taurus, you will also need to use two tach adapters PN# 8912. The same PN# 6215 will work on the Buick, for the Buick you will also need to use 3 coil interface modules PN# 8870, one per coil." Not sure whether the MSD tech meant that the tach adaptors have to be used on the Reatta also. The issue is whether our 1 piece coil really takes 3 interface modules [pn# 8870] or just one, pn# 8878.

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Basically I have seen two coil pacls for the 3800 DIS (distributerless) ignitions. A single unit with three coils (square on top - Type I - Maganavox) and one that has three individual round units (Type II - Delco Remy).<P>According to my parts book the individual DR units were used 1986-87 and after 1991 but the triple Magnavox unit was used on all 88-90 Reattas<P>Electrically, they should be both the same though the Magnavox uses individual wires and spade clips to connect the coilpack to the ESC while the DR uses through pins.<P>I believe the tach is fed by the ESC, the coil pack has nothing to do with that. Since the ESC (mounted under the coilpack) is much more than just a coil - why the connector has 18 leads - but handles all management under 400 rpm, I would be surprised (has happened before) if a Ford unit would work without modification.<P>Just checked the MSD web page and could not find the 6515 (does not have a search) - what exactly is it ?<P>These coils are both functionally the same, each firing two plugs (first saw that on a Honda 150 c.a. 1964) at a time (one is on power stroke, other is not). GM claims that most of the energy is directed to the plug on the power stroke. However a single fouled plug will take out two cylinders.

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Padgett, the correct MSD part number is 6215 not 6515. In reading your post, you characterize the Magnavox unit as Type I, but say it was used on the later cars, 88-90. On my 90, the coil pack has three square "boxes" as part of the one-piece top secured to the base by six screws. Can't see where the manufacturer name is stamped, so not sure if it's Mag or DC. Will email my tech contact at MSD to see if he really meant the Ford tach adapter can/must be used on the Buick.

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Yup - the square ones look like three individual parts but are in a single plastic housing. On the Magnavox the three coils appear square, on the DR they appear round ("oblong" or "not square" is probably more accurate).<P>The Magnavox (one piece) is what is on both our 88 Reatta and 90 Bonne. The 92 TS has the round ones.<P>And now found the 6215. From the specs it looks like it has internal coils but would need adapters from the ESC to the MSD and from the MSD to the plug wires. (Latter may be simple but cannot tell from the web page.<P>Suspect the 8870 "coil adapter" is the MSD->plug wire and the 8912 is ESC->MSD. If so you will need three of each & am not sure the 8912 will work with the Magnavox ESC, might need either something custom or the DR ESC module. Is only six wire so <span style="font-style: italic">should</span> not be difficult.<P>As to the DR being used earlier, that is what my 86-93 parts book shows DR in 86, both DR Type II and Magnavox Type I in 87, Mag in 88-.<p>[ 01-11-2002: Message edited by: padgett ]

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I am not sure how you would install an adapter module of any kind. There are no external connections between the coils and module? The block they offer for the earlier GN's would be just the ticket, but it doesn't appear they offer anything for the later models but perhaps they have developed something recently that isn't in the catalog. The signal that goes to the DIS-4 module is the stock wire that connects between the coil and module below. It looks to me like all the coil wires are cut between the module and coil pack and the MSD module is essentially spliced in between. The trigger wiring from the stock module is routed to three wires in the twelve pin connector for the MSD module and another three wires from the MSD module return and connect to the coils. The MSD boosts the voltage to over 450 volts in the primary wiring and also adds the multiple spark feature. If the MSD harness is long enough, all the connections could be made inside the space between the coil and stock module, which would be relatively weatherproof, especially if sealed butt connectors are used. You would have to make a harness routing hole somewhere to get the wiring in and out. This information is from the 130 page MSD wiring and tech tips manual.

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I see what you mean by the tach and coil adapters. The coil adapters are for the individual coil type of coil pack, not the unitized unit we use. According to the FSM the tach signal is generated inside the ignition module, before the circuits to the coil, and lists a white wire that is labeled "not used". The question is, does the MSD module require a tach connection to operate? The only other wiring, (aside from the trigger wires), in the diagram is the twelve volt power wire that charges the coils. This is also cut and goes to and from the MSD module. Aside from that, there is a separate heavy gauge hot and ground wire to the MSD unit. If you have the MSD unit, does it have a single twelve pin connector? All twelve wires are accounted for in the wiring diagram, and none of them are "tach". There should be a tach output connection on the DIS-4 module itself, but I do not believe it is required with our ignition system, the tach signal is generated before the point the MSD module is spliced in.

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Looking at a picture of the MSD 8878 Buick interface module in my JEGS catalogue, it appears to fit under the plastic cap of our module with holes where our 6 cap screws are. If the tach pickup is earlier in series, this would seem to be the only wiring interface required. No?

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The GN system uses a DIS system that is similar in appearance to the Magnavox DIS used in the Reatta, but has all different part numbers. I would expect that the main difference is that the GN system uses a single crank sensor, while the 3.8c uses a dual crank sensor. This is from memory, so don't go wild if I'm wrong. The 3.8c does use a dual angle crank sensor though, which I don't think they had when the GN was built. The ignition coil has a different part number than the Reatta, but they appear the same and actually will interchange okay, I've tried it. I believe the GN version has a hotter secondary ignition for higher rpm operation. <P> This is a neat idea, to put msd ignition on, but I think you will be dissapointed. The 3.8c should idle smooth in stock trim. Boosting secondary ignition is a good way to overcome a problem that is already there, such as improper mixture(restriced injectors) and might even help in the case of poor valve sealing. <P> I use aftermarket performance ignition products to improve performance in high rpm applications, and to couteract any carbuerator indescrepencies due to environmental changes, to avoid intermmitent fouled plugs. <P> I'm sure the upgrade will increase your satisfaction with the car, but don't overlook the root cause of the rough idle. Failures of the Magnavox ignition coil due to low secondary ignition votage are common, but causing extended crank times in cold weather, not rough idle. I don't know much about your application(age and miles), but I would look for poor sealing valves(leakdown test) or restricted injectors(injector balance test). The 3.8 is well known for wearing out exaust valves, mainly in hot climates. If you can get an injector balance test, all injectors should be within .5 lbs of each other, at MOST. The test is most accurate with the engine at ambient temp. Results are hard to read if the fuel heats up in the rail as the test is conducted.

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More thoughts, if the msd adaptor slips between the coil and module for the GN, the system will function exactly the same on the Reatta. It appears to be a primary ignition amplifier, so I would strongly reccomend the msd coil to go with it. Otherwise, I would expect to burn out the factory coil quickly.<P> The spark from an msd system on a spark tester is an impressive sight, especlially compared to stock. Fireworks galore, and you don't want to be anywhere near of it for fear of being bit! Only downside is that it will wear out the spark plugs faster. Nothing but improvements for the driveability aspect.

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Given Bigrog's latest post, it appears the 8878 interface module is the right application for the magnavox on the Reatta. Will try it. I also agree with the earlier post. I would be chasing my tail to put $375 worth of aftermarket ignition on to mask a problem that should be resolved. As I mentioned, the aftermarket ignition was offered to me provided I agree to use it. The interface seems like the best way to make it work properly. Thanks to all who commented. Once installed, I will report on any changes in performance/mileage. Two other questions. I run a Jacobs ignition on my Dodge Transvan. Jacobs prohibits the use of multi electrode and platinum plugs because they are not up to the hotter spark. Should I assume the same about the MSD unit? What about the stock plug wires?

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