Ignition failed... agian

[bigbz28]

I have a 1974 75hp Chrysler. The ignition box failed again and left me stranded. Getting pretty sick of it. I read in another forum a very old thread about adding a condenser for the distributor and replacing the CDI box with an automotive coil as well as replacing the spark plugs with those of lower voltage. I tried this with a can style coil and it ran good for about a mile then started misfiring. The plugs well faulled out. I figured it could be the coil wasn't strong enough and that being oil filled and mounted upside down had an affect so I replaced it with a dry 30K volt coil but still am having the same problem. Has any one attempted this or have some input?

 

[Frank Acampora]

Try a slightly hotter plug or try the Evinrude QL77 plugs. I don't have my Clymers in front of me but the magneto ignition Chrysler engines used something like a Champion J6J--Perhaps Nordin will chime in. He knows plugs for most Chrysler engines.

 

[bigbz28]

What about using the factory spark plugs with the 30K volt coil?

 

[Nordin]

If you have the MagnaPower electronic CD box system you shall use surfgap plug such as Champion L20V or equal from an other brand.

For battery ignition system (Automotive typ) with auto typ ign.coil and condenser, Chrysler recomended from factory Champion J4J.
You can look at the web and search for equal from other brands.

You say that the plug fouls after a short time.
Well, gap the points to 015 in and check the setting of the air/fuel mix screw on the carbs.

If the setting is to rich the plugs will foul because of a to rich mixture.
The setting should be 1 1/8-1 1/2 turn out from seated. DO NOT set them leaner then 1 turn out from seated.
The engine will idle better BUT you may melt pistons.

 

[Frank Acampora]

If by factory plugs you mean the surface gap L20V then don't do it. They simply will not fire with an automotive coil. If you are going the use a racing, high output coil, they may fire but understand that the surface gap plugs are more prone to fouling than bent electrode types.

 

[bigbz28]

Just ordered the J4J plugs and gonna check the points gaps this weekend. What should the gap on the plugs be?

 

[Frank Acampora]

You can't go wrong with .030 gap on plugs Points should be gapped at .014 You may need to adjust this to increase dwell time for a hotter spark.

 

[bigbz28]

OK, I finally got the boat back to the lake but still have the same problem. Installed J4J plugs gap at .030, new points gap at .014 Mixture screws at 1 1/2 turns. Still fouling out plugs. Fuel mixture is at 50:1. At this point I'm about ready to spend the $300 on a new CDI box...

 

[pnwboat]

I don't know but if you have to spend $300 for a failure prone OEM ignition box, I would consider trying to adapt an MSD, Accel, or Pertronix automotive type ignition system or something similar to it. I think I remember a Forum member that did just that and it worked well.

Only drawback to adapting an automotive ignition system:

1. Need to see how much current draw the system pulls. Since it's a battery driven system, it may draw significantly more current than your outboard charging system can deliver. I know the MSD system is a high performance system and generates a really hot, long duration spark, but it may pull a lot of current to operate.
2. Mounting the ignition box. They're usually bigger than the OEM system.
3. Might use a specific coil for the system....additional cost.

 

[Nordin]

Are you runing the engine with automotive style ignition system (automotive coil and condenser) or CD module box?
Automotive style and you must use plugs with bent electrode. CD module box, you have to use surface gap style

After how long time does it fouling plugs and are you runing at idle for a long time?
1 1/2 turn out of the mixture screws is maybe to rich. Try 1 1/4 or 1 1/8 turn out.
Check the fuel diaphragm, maybe it is torn and that will result in flooding the cylinders.

 

[bigbz28]

Auto style points and condenser with spark plugs with bent ground electrode. Tried running it with mixture screws 1 1/4 and 1 1/8. Plugs foul out very quickly, cant even get out of no-wake area, as soon as I throttle down it stalls. Replaced diaphragm last year. One thing that I did notice is that after running and I tilt the engine that fuel drips out of the carbs. Perhaps I need to change the float valves but I don't think that they would all go bad at once..

 

[pnwboat]

Fuel dripping out of the carbs while tilted is pretty much normal.

When your motor is tilted down in the normal running position, make sure your primer bulb gets firm after squeezing 4 or 5 times. If it doesn't get hard, then you have a leak some where. Usually a needle valve in the carb.

 

[bigbz28]

No problems with fuel drip when engine is in normal position, and bulb does get firm.

 

[Nordin]

Do you know if it stop because of to rich mixture or lack of fuel.
If to rich set the mixturescrews leaner, go back from 1 1/2 turn to 1 1/4 or 1 1/8.
You can go for leaner until 1 turn out, BUT not leaner than that.

Have you checked the level of the carbfloats? Should be parallell with carb casting edge of the bowl when turned upside down.

 

[bigbz28]

I would say rich mixture since the plugs are wet. And yes, the floats are level with the crab casting

 

[bigbz28]

No Title

I don't know but if you have to spend $300 for a failure prone OEM ignition box, I would consider trying to adapt an MSD, Accel, or Pertronix automotive type ignition system or something similar to it. I think I remember a Forum member that did just that and it worked well.

Only drawback to adapting an automotive ignition system:

1. Need to see how much current draw the system pulls. Since it's a battery driven system, it may draw significantly more current than your outboard charging system can deliver. I know the MSD system is a high performance system and generates a really hot, long duration spark, but it may pull a lot of current to operate.
2. Mounting the ignition box. They're usually bigger than the OEM system.
3. Might use a specific coil for the system....additional cost.

This is what I am considering. Not the OEM box, but I would like to know if these are prone to failure also.

 

[bigbz28]

Any feedback on this CDI? Will it work in place of the old Magnapower box?

 

[Nordin]

Do not know if the 115-3301 is prone to failure. I have it on one of my 75Hp Chrysler 1977 with preamp trigger. Still running very well, BUT remember it does not have any tach wire.
It is the aftermarket spare from CDI Electronics and it replace the OEM box.
The OEM is N/A from Mercury, Franz Marine might have new OEM boxes, BUT I think it is more expensive than the 115-3301.

 

[Glastron_V210]

Replaced on of mine with the CDI box last year...running fine for two years now. This is on a '76 135 Chrysler. I had to do a stator as well. I suspect a stator issue was killing the CDI boxes, but can't prove it. I used the CDI stator as well...it's a nice part.

Chay

 

[Nordin]

If you by stator mean the alternator it has nothing primarily to do with the ignition.
This ignition system use 12VDC from battery to charge the capacitors in the CD box.
The stator/alternator charge the battery through the rectifier.

Later Prestolite typ has a stator that charge the capacitors in the CD box.