cd ignition

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novacane

Seaman
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Mar 8, 2002
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70
ok boys and girls hers the lowdown im a cheap scate a freind gave me a 1972 85hp evenrude v4 someone has removed the cd ampifier and recifier bridge so i get out my rocket sceintist stadis strap on the brain <br />look through some old auto parts i have laying around i find a gm 4 pin ign.control module i figure the points would be the trigger i ofcourse changed out the ign coil too wired in this module she fired right up and ran great!!!!! i was stoked!!! does anyone out there know if ill have greif down the road the way i see it should work just fine and does so far but havit lake tested it yet im now wiring in a doide pack or rectifer bridge from a toyota alternator <br />once again im thinking a diode is a diode <br />right? should work i hope any help with this is deeply appericated thks :D
 
JB

JB

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Mar 25, 2001
Messages
45,907
Re: cd ignition

Howdy, Novacane. Very creative! You might have some trouble with the fact that your parts weren't intended for a marine environment. Be sure they stay dry.<br /><br />Unfortunately, a diode is not always a diode. They differ in how much current (forward) they can stand and in how much reverse voltage they can stand. <br /><br />This is probably not a problem, because I suspect that the diodes from the Toy are at least as strong as the original OMC diodes.<br /><br />Good luck.<br /><br />Red sky at night. . .<br />JB :)
 
12Footer

12Footer

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Re: cd ignition

I agree with J.B. on the environment thing.<br />And I'm certain the heat range of the plugs cannot be within spec, and that would be my main area of concern..A plug too hot or cold can really damage an engine (holy Piston syndrome). So see if you can get a plug reccmmendation from GM,or even use a plug of the same heat range as the GM plug this unit supplies.<br />But you get the 12Footer inventive-solution award for 2002! Ya don't get any trophy or nothin, but you sure got an instant fan club :) <br />GM RULEZ!<br /><br />
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P

petryshyn

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2,851
Re: cd ignition

Hi novacane<br />Couple things I'd be concerned with:<br /><br />>The input of a GM module draws miniscule current and won't keep the points clean.(current has a cleaning action) A few months of sitting, and it may not start. You may run a resistor from points to battery to address this.<br /><br />>The GM module gets hot as hell, so be sure it is mounted on a flat unpainted aluminum surface (preferably on a water jacket)with die-electric grease between. If you don't, IT WILL FAIL (in the middle of the lake ofcourse!)<br />>The GM module doesn't like anything over 17V. and if you don't have a regulated charging system, you may see this voltage (best be running a regulator).<br /><br />>The GM HEI ignition induces alot of radio frequency interference into the source voltage line, and has a condenser built into the original wiring harness at the distributor to reduce this. I'd hunt one down and install it as close to the module as possible. If you don't, fish finders, tachs, radio's and most any electronics on board may be affected.<br /><br />>last but not least, as JB and 12'er stated, the GM module is not perfectly sealed(had many apart) Once you get it properly mounted, caulk all edges and bolt holes thoroughly with non-corrosive silicone(commonly known as silicone II)<br /><br />>You didn't say which coil you put in. Choose one that has a coil tower on it and is from a variable dwell system. GM HEI with external coil or Ford TFI etc. A conventional coil may not produce enough energy at 5500rpm and result in misfires.<br /><br />>Pending on which Toyota alternator, the diodes should work, but since there won't be any airflow across the heat sink,(and the positive heat sink is isolated from conduction of heat) I'd go with a high output assembly. (I've used 100amp alternator diodes in battery chargers, and they get extremely hot with just 15amp with no cooling) If the stator has only 2 leads, I'd go with a generic rectifier block which can be mounted to the water jacket and cooled properly by conduction rather than relying on air flow. They are only $10<br /><br />Good luck and carry a spare module for safety! :)
 
12Footer

12Footer

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Re: cd ignition

Hey Schematic, Me thinks you're the guy to answer a question I have..What would cause a consistant,yet weak spark, given that the coils,switchbox,plugs,and stator have all been replaced? (This is an 88MERC 15HP).<br />I have checked all these components,and they are within spec. Yet the spark is puny, yellow,and I'll bet I could grab a plug anode! This engine has a consistant miss and weak spark.<br />Any ideas?<br />I'm also thinking this is water getting-into the cylinders,but can't tell, even with the old plugs.<br />Gonna pull the head, once I find new gaskets for it,but compression is 110 and equal.
 
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petryshyn

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Re: cd ignition

Hi 12'er<br /><br />My father just called to go for breakfast. When your father of 82 wants to go for breakfast, you go for breakfast!<br /><br />Do you have a DVA adapter? If you don't, dig up a .5uf - 1.0uf 500V - 1000V capacitor and four 1n4007, or 1n4008, or 1n4009 diodes and one resistor 10 mega-ohms 1/4 watt.<br /><br />Your problem can only be one of two things.<br /><br />>not enough primary voltage to coil<br />>bad coil and or coil wire<br /><br />We'll talk when I get back this afternoon.....<br /> :)
 
12Footer

12Footer

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Re: cd ignition

No i don't, but can borrow the peak reading meter at werk on weekdays. I would like to make an adapter tho (so I don't have to do that anymore) :) <br />Can relate to the dad.
 
P

petryshyn

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Re: cd ignition

>are you using a spark tester or old plug?<br />>do both cylinders have weak spark?<br />>did you measure charge voltage at the switch box?<br />>did you measure coil primary voltage?<br /><br />I'll whip up a DVA adapter schematic when I get a chance.....
 
12Footer

12Footer

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Re: cd ignition

The plug (both cylinders) shows a very weak,yet consistant spark.<br />I've also had the timing light inline, and tried both cyclinders. The spark is weak enough to skip on the #1 cylinder,on the timing lightwhich is why I think the problem is there. But both the new and old switchboxes perform identicle. I can't measure the charge RMS meter, and the manual doesn't even list what should be present.<br />As for the DVA adapter, that would be fantastic! I can still use one for my Force<br /> Take your time whipping-up the schematic, schematic :) ,as I have a busy work week comming-up (we just got a saweeet new machine at werk,and will be in training Tues-Friday. I'll show you some pics of it,when I get them U/Led.
 
12Footer

12Footer

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Re: cd ignition

And ohms are all to spec (they ARE in the manual.
 
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petryshyn

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Oct 3, 2001
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Re: cd ignition

back again....just bought new washer and dryer for wife...cause if momma ain't happy, ain't nobody happy! :D <br /><br />Even though the spark LOOKS weak, how much of a gap will it jump. Some CDi systems have very little spark duration and the nice blue ionization we all have come to recognize and love doesn't have time to occur. Seems to me mercs charge coil voltages should be either 100v or 180v or 1000v (plus or minus 10%) I could be wrong, as I'm no expert....<br /><br />Measuring resistances don't tell much of a story.(unless you see an open) Even good values can yeild low voltages caused by leakages to ground. You gotta measure the voltage getting to the coil primary.... <br /><br />As far as the timing light is concerned.....some automotive lights won't trigger on some low duration CDI's<br /><br />Be sure you are using the recommended plugs. Some CDI's require the added inductor in the plug to regulate and prolong spark duration.<br /><br />Maybe the misfire isn't ignition related....just a thought.
 
12Footer

12Footer

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Re: cd ignition

All good points, Schematic. And I've been persuing it from the water jacket angle lately, because the entire ignition is new...<br />The arc will make the .40 gap no sweat, so you may be correct in tghe theory that it is suposed to be this way.<br />I'll let you know how I fare. Thanks,man.
 
O

ODDD1

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Jan 23, 2001
Messages
1,054
Re: cd ignition

12 footer, i would like to poke my nose in this one....those ignition systems will jump a 1/2" air gap cranking with the rope...cosistent weak spark is probably a bad low speed stator winding, causing low input voltage [under 100v]....dont bother pullin the head, it dont come off! that is just a water jacket cover, pull the exhaust covers to inspect the cyl...most common water ingestion prob on these engines is the exhaust gaskets anyway...<br />and an ATTABOY to novacane..resourceful butchery at its finest!
 
N

novacane

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Mar 8, 2002
Messages
70
Re: cd ignition

ok heres what ive done and should have added <br />offcouse the ign module is mounted on a 6inch by 1inch block of alliumun witch is mounted hi up here water jackets with dietric compound for good heat transfer <br />as far as the plugs go ive maintained the <br />040 cap and to help keep detention from rearing its ugly head ive back total timing down 2 degrees and plan on keeping very close eye on the plugs for signs overoverheating my 70 nova runs from3k-8k and ive found a great racing plug for that j63y champoin fine wire race plug(unshourded spark) very cold oh i have jetted the carb up one size too great idea on the resister to the points did that been thare should have say that too used one from a chrysler <br />in addition to what ive mentioned ive allso <br />sealed the module with honda bond cant see it being in any worst inveriment than it siting in a 75 chevorlet that lives in say south fla lol thank to you all for taking the time to replay to my little project thanks steve :D
 
N

novacane

Seaman
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Mar 8, 2002
Messages
70
Re: cd ignition

rats!!! once again im not telling the hole story last thing i did replace out the solid copper core wires with lets see what ive got lying around oh here we go some peices of 8.8 msd spiral core wires i cut them to lentgh locked on the screw ends and reused the old boots and tie straped them to the cap did that before i even tryed to start it sorry be like a month now and i forgot lol thanks all novacane stands for my 11 second streetable 70 nova i built less than 3500. no nitrois either :)
 
P

petryshyn

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Re: cd ignition

sounds good, but use the stock plug. the heat range will haunt you.......(famous last words)
 
N

novacane

Seaman
Joined
Mar 8, 2002
Messages
70
Re: cd ignition

yes im using the stock heat range for now another ? i run 50/50 of 100ll ave gas and pump 92 in my nova ive also install a timing computer works great! now my ? is will this work ok in the evenrude as lead is a great octane booster, anyone see any greif with this combo lets face it detention is the leading cause of engine failure those two flame fronts colidion spells greif next do thay or can i install a magmetic pickup in this older unit? i lou of the duel breaker points?
 
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