Car coil conversion

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firemedic19077

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Feb 19, 2002
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There was a post about being able to perform a car coil coversion on a 1968 Evinrude / Johnson. I have a 85HP manual shift and was wondering what parts are involved and the instructions for performing this conversion.
 
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almost retired again

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Feb 9, 2002
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Re: Car coil conversion

Hello Firemedic,<br />I'll try to answer your question. This works if you have a point system and a distributor. If so all you need is a 12 volt ign coil. Run a 12 volt switched lead to the pos. terminal of the coil. The neg.side of the coil will go to the breaker points. The center tower of the coil will go to the center terminal of the distributor. Hope that you understand, as the saying goes a picture would be worth a thousand words.<br />Good luck
 
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petryshyn

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Re: Car coil conversion

HI Gents<br /><br />firemedic19077 <br /><br />A few issues to consider. If you're running over 5000 rpm, HEI module is your best bet. If you're running 5000 or less, points, condenser, coil and ballast resistor will surfice.<br /><br />Let us know what you have for ignition, what rpm you will run, and I'll wittle you up a schematic....
 
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Franki

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Re: Car coil conversion

Be careful doing this, hopefully schematic will see this topic and contribute as he could very likely be more specific then I can.<br /><br />basically it will then work much like a car engine..<br />the coil needs two feeds, positive from your ignition, and negative, which comes from the body of your motor, through the points which open and close to feed the coil when it needs to fire off.. the coil then feeds through to the distributer, (which in these models is under the flywheel as I understand it.) the distributer serves the same purpose as in a car engine, it has a rotor that sends the coil charge through to the relevant cylinder to fire the plug.<br /><br />the basic conversion is simple as ARA describes.. however there may be some other things to consider, for example plug type and condensor.. thats why it would be handy if Schematic posts and gives more details on this.<br /><br />I tried to get my outboard mechanic to give me all the details on it, so I could post them, but he makes 300 bucks per conversion so he wouldn't part with the info. (and I got a new powerpack for mine, so I couldn't just see what he does.)<br /><br />I have spoken to a couple of outboard mechanics about it, and the concensus was mixed, one swore by it, the other said that the points can get worn very quickly with the extra load a car coil entails. (then again, maybe that mech didn't take plug type and condensor into account.)<br /><br />hope this is of some assistance.. as I said, if schematic is around, it can probably tell you everything you need to know.<br /><br />rgds<br /><br />Frank
 
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Franki

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Re: Car coil conversion

Hey Mr Schematic..<br /><br />If you were to write up both methods into little how-to documents with pics and stuff. you could probably sell them for $10 bucks a piece or something.. get something back for your hard work helping people..<br /><br />I'd buy both just for reference purposes.<br />(I'll bet a few outboard mechs would buy them too.)<br /><br />you could use Paypal to take payment and ship them online.<br /><br />You'd have to make a couple of versions of each for OMC, Merc, but each would more or less be an edit of the other anyway, so it wouldn't be that hard.<br /><br />have you ever considered this?<br /><br />(I can help you setup an online shop for this if you like.. its what I do for a living.)<br /><br />just a thought, but from looking over what I have gotten from you in the past leads me to think alot of what you do could earn you some beer money.<br /><br /><br />rgds<br /><br />Frank
 
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firemedic19077

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Re: Car coil conversion

I am sure it is less that 5000 rpm because of the points, condenser, coil and ballast resistor. :)
 
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petryshyn

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Re: Car coil conversion

Hi gents...<br /><br />I won't charge you guys! We're all one happy family :) <br /><br />firemedic19077<br />Why are you considering this modification?<br />I thought you had spark?<br /><br />One ugly detail that gets forgotten is that these modifications require current for ignition.(if battery goes dead, you're paddling') If your charging system only puts out 3-5 amps, the battery will aventually go dead. You've got to have atleast a 10 amp charging system to consider this.
 
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novacane

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Mar 8, 2002
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Re: Car coil conversion

i have pics of my outboard on witch ive done<br />away with the cd pack and replaced it with a gm ign module witch still has trouble saturating the coil above 5000 thats the purpose of like a msd ign box muliple spark throws 1 spark than another behind it other wise ive found the gm ign module to work great!!! few other things you have to do i replace the wires with a good spirel core wire, is sheilded ect... ect.... i have it posted on this board under cd igntion i think good luck
 
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firemedic19077

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Feb 19, 2002
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Re: Car coil conversion

Just something that would be nice to know and even change over to if it is reliable. Started out water in lower unit, then, would not shift into forward, then, starter went out, then, the starter and the neg battery cable became hot and started smoking. Hot enough to melt the terminal, so now having to rebuild the starter again, and having trouble getting her started. So, what else could go to the ****er next? :mad: :( :) :confused:
 
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petryshyn

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Re: Car coil conversion

Hi Gents:<br />I've done some experimenting using 2 types of GM modules. There is a fire hazard if the key is left on and the points are open. The coil remains powered and draws 6 amps. Needless to say, it overheats badly and could catch fire! Sure it'll run the engine, buy I don't feel its safe.......sorry.<br /> :eek: :eek:
 
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petryshyn

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Re: Car coil conversion

With respect to installing a coil, condenser and ballast resistor........I see some potential problems. First off the cam on the crank is designed for a very small gap. This small gap will allow point arcing. Secondly. the point contacts are smaller than auto points. Although this mod will work, it will result in very short point life. Last but not least, it requires power from the battery, and if you have a small charging system, the battery will eventually go dead.<br /><br /> :( :(
 
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novacane

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Re: Car coil conversion

ok mr schemedic ihave just done your test <br />with a 4 pin gm module a ford tfi ign coil <br />i tested temp of coil before test (with my infred temp sensor) i rotated the flywheel till i seen my amp gauge jump from about half and amp to a little over 6 amps in 15 mins of leaving it this way my coil rose only 14 degrees in temp not even close to fire hazzard you didnt state witch modules you used (hope it wasnt one with a advance <br />in it) like a 7 pin but any how i did dig up a msd 6al ign box offcourse is a cd igniton with muliple spark the whay i see these are cheaper than most of the oem units out thare<br />and from reading this forum arnt real reiable ether oh well with that box im installing the antivibe pack and anti vib msd blaser coil should rock and roll lol i hope
 
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petryshyn

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Re: Car coil conversion

Hi novacane<br /><br />Is it possible that you have quite a voltage loss through the accessory circuit of the ignition switch and the related wiring? That would account for less heat occuring. My test was using full 12V to the module/coil. I used a 4 terminal and a 8 terminal GM module with the OEM coils. Both modules got very hot and coils also spiked in temperature. Nothing failed, but over time, the accumulated temperature will damage one or the other. If the power transistor fails shorted, the coil will be a fire hazard. 6 amps is large enough to flatten the battery in short time and certainly too high a current to be supplied by the ignition switch when added to the existing accessories.<br />Again, if the charging system fails, and the battery goes flat......no way of starting her... <br /><br />The Ford TFI module is normally triggered by a hall effect chip. This chip will send a signal if engine stops at a given position as well. It doesn't appear to trigger the module if engine is stationary. This may be a better suited module......atleast for the sake of a fire hazard. I haven't tried one yet....<br />One must admit, the OEM goes through the trouble of building CDI systems for a reason.<br /> :)
 
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