74' 55hp with ignition coils from car

[RobB86]

I recently bought a 74 55hp and the previous owner installed what I believe are automotive ignition coils. The have an internal resistor. Are these going to be OK or do I need to get new ones? It ran when I bought it but the flywheel key got sheered. I'm hoping that will get it running again. Any input in these coils would be appreciated. They are universal coils is my guess? Not really sure.

 

[Nordin]

They are a bit lager then the factory made and may have to be mounted at odd places, BUT they will do the work,
No problem.

 

[RobB86]

Ok great to know, thank you sir.

 

[jerryjerry05]

Nordin, does it make a difference if the coils have an internal resistor or not??

 

[Nordin]

If you mean an internal resistor for "cold"start a car, that allow you to lower the voltage to about 9 VDC by bypassing it, the answer is yes.

Avoid these ones. The resistor is bypassed at cold start for getting a good spark when the engine is cold and the starter requires a lot of currant and the voltage will drop.
BUT this situation does not appear in a boat in the summer.
Also try to find a automotive coil with about 10kOhms at secondary side. The stock ones has about 8kOhms.

REMEMBER do not use automotive coil on early 45Hp and 55Hp engines with Magnapower ignition with points (I think from 1969 to about 1980).
The stock coil for this system which was a battery typ of system that need a battery to charge the capacitors in the CD box and the system did not have any condensers under the flywheel. These coils had a secondary resistance about 550-600 Ohm.

 

[RobB86]

I had a sheared flywheel key and thought it was why it wouldn't start. I just put Inca new one and still no start. Checked and the key was sheared again. Also how do you gap the points since when the flywheel spins the gap changes?

 

[Nordin]

You set the gap of the points to 020 in. The setting is done when the points is at the highest part of the camcurve.

As your flywheel key has shared a couple of times check the crank tape and the flywheel tape.
If it is scored, lapp it with valve grind coumpound.

Then you have to torque the flywheel nut to spec, 80 foot pound. If you not do that the key will share again.

 

[RobB86]

Thanks I'll do that when the next key comes I'm the mail.

 

[RobB86]

Gapped the points, lapped the cam and inside of the flywheel and installed the key. She's purring like a kitten. Now it's not circulating water though. It has a new impeller in it. It was circulating and in the process I installed a gasket for the thermostat. After that it didn't want to circulate by itself. If I hook a hose to the copper pipe while the lower unit is off it will circulate. When I put it back together put it in a garbage can full of water and fire it up nothing?

 

[RobB86]

I installed a horn to the over heat wire so I'm gonna take it out and hopefully it just wasn't in enough water.

 

[RobB86]

Took it out but didn't get very far. Got up on plane for a min or two then slowed down and it died. Motor over heated. Not sure of the damage yet but horn didn't go off ans I guess the water pump isn't working.

 

[Nordin]

When you put the LU to the engine did you check that the coppertube lined up with the output from the impeller housing?
The housings with a plastic tube connection are easier to line up then the housing with a rubber connection.

How did the impeller housing look like when you changed the impeller? Check the stainless steelplate and the inside of the housing.
The surfaces should be smooth and not so much pitted. Also check the key for the impeller, it might be loosen.

 

[RobB86]

I'm pretty sure I got the copper tube lined up right with he housing. It is the rubber one not plastic. It is a little cracked. I didn't replace the impeller the last owner did right before I bought it. It's only a few months old if that. It was working fine and I put a gasket in the thermostat housing, since then it doesn't pump water. I took the lower unit off to make sure it wasnt clogged and to see if it would circulate with water directly to the tube. I didn't think it was necessary to take the impeller housing apart. It is together pretty good he used some gasket maker to hold it together. It started right up today after playing with the throttle. I hope I don't need a headgasket after over heating yesterday. The bolts are rusted pretty bad from the thermostat housing leaking. I did try to run it without the thermostat as well and it still wasn't circulating water. I'm gonna take the lower unit back off and take the impeller out to take a look. I'll let you know how it goes. Thanks for all the help.