Ok so I saw a few of us here are having some of the same problems and putting a new coil in has seemed to solve it for a little while, until it goes bad again.
I replaced my coil and now the engine runs great. But I can still feel that the coil is getting hot. Not as hot as the last one but almost.
So tell me if this sounds right.
In my manual at the beginning of the part that talks about breaker point IGNs it gives a general how it works desc.
It says
"Beginning at the key switch, current flows to the ballast resistor and then to the + side of the coil. When the resistor is cold its resistance is approximately 1 ohm. The resistance increases in proportion to the resistors rise in temp."
Ill summarize the next part.
It goes on to say that when the engine is at idle or slow speed the cam on the dist shaft revolves at a relatively slow speed, making the breaker points remained closed for a slightly longer period of time. Because the points remain closed longer more current is allowed to flow and the current heats the reisitor and increases its resistance to cut down on current flow, thereby reducing burning the points.
Durnign high RPM engine operation, the reduced current flow allows the resistor to cool and reduce resistance, increasing current flow.
So, I dunno about everyone else but the coil I have says it is supposed to be used with a .75-.85 ohm ballast resistor. The manual says at idle the resistance should be about 1 ohm. I measures it at idle at 1.4ish.
So could this be why my coil is getting hot still and why it will most likely fail again sometime? My understanding of this is that at high RPMs the resistance should be less than .75 because the resistor will coll dropping the resistance. But if I have 1.4 Resistance at idle then at high RPM it will most likely not even drop to .75. So there is too much resistance which is causing the coil to work too hard and get hot, then stop working.
Which could be why the engine was not working good after a couple hours of run time. Maybe the coil just was getting too hot because it was dealing with too much resistance?
The ballast resistors are $12. In the manual it says that the purple/black wire goes straight to the starter sol. So if I disconnect that wire then run another wire form the starter sol to the .75 ballast resistor then to the coil and run it for a while, if it runs good and the coil doesn't get hot or as hot then this must be better than the OEM resistor that is built into the wire?
I went to a marina that sells OMC parts and they could not confirm what the resistance of the OEM coil is. And according to the manual the resistor should be 1 ohm at idle and mine is 1.4. So maybe the resistor wire is junk and I should replace it and the coil with OEM, but if I am correct in my reasoning on this then for $12 I can figure this out right? Id like to figure it out for $12 first then spend the money on a new OEM coil and resis wire.
Does this sound right to you guys?
If this is true and a problem then maybe this is why the others that were having the same problem as me and which a coil fixed the issue (and kept blowing coils) maybe this is the problem?
I dunno maybe Im thinking about it too much. My engine runs great now. But I have a feeling the coil is still too hot.
I replaced my coil and now the engine runs great. But I can still feel that the coil is getting hot. Not as hot as the last one but almost.
So tell me if this sounds right.
In my manual at the beginning of the part that talks about breaker point IGNs it gives a general how it works desc.
It says
"Beginning at the key switch, current flows to the ballast resistor and then to the + side of the coil. When the resistor is cold its resistance is approximately 1 ohm. The resistance increases in proportion to the resistors rise in temp."
Ill summarize the next part.
It goes on to say that when the engine is at idle or slow speed the cam on the dist shaft revolves at a relatively slow speed, making the breaker points remained closed for a slightly longer period of time. Because the points remain closed longer more current is allowed to flow and the current heats the reisitor and increases its resistance to cut down on current flow, thereby reducing burning the points.
Durnign high RPM engine operation, the reduced current flow allows the resistor to cool and reduce resistance, increasing current flow.
So, I dunno about everyone else but the coil I have says it is supposed to be used with a .75-.85 ohm ballast resistor. The manual says at idle the resistance should be about 1 ohm. I measures it at idle at 1.4ish.
So could this be why my coil is getting hot still and why it will most likely fail again sometime? My understanding of this is that at high RPMs the resistance should be less than .75 because the resistor will coll dropping the resistance. But if I have 1.4 Resistance at idle then at high RPM it will most likely not even drop to .75. So there is too much resistance which is causing the coil to work too hard and get hot, then stop working.
Which could be why the engine was not working good after a couple hours of run time. Maybe the coil just was getting too hot because it was dealing with too much resistance?
The ballast resistors are $12. In the manual it says that the purple/black wire goes straight to the starter sol. So if I disconnect that wire then run another wire form the starter sol to the .75 ballast resistor then to the coil and run it for a while, if it runs good and the coil doesn't get hot or as hot then this must be better than the OEM resistor that is built into the wire?
I went to a marina that sells OMC parts and they could not confirm what the resistance of the OEM coil is. And according to the manual the resistor should be 1 ohm at idle and mine is 1.4. So maybe the resistor wire is junk and I should replace it and the coil with OEM, but if I am correct in my reasoning on this then for $12 I can figure this out right? Id like to figure it out for $12 first then spend the money on a new OEM coil and resis wire.
Does this sound right to you guys?
If this is true and a problem then maybe this is why the others that were having the same problem as me and which a coil fixed the issue (and kept blowing coils) maybe this is the problem?
I dunno maybe Im thinking about it too much. My engine runs great now. But I have a feeling the coil is still too hot.
