voltage to coil

[searayric]

hi ....82' mercruiser 228 (305) or 266 (350)..what should voltage going to coil be with key on ...im getting 4.5 v ...<br />with engine running the voltage to (+) side of coil is 10.8 >> on (-) side is 7.4-7.8v feeding points...after having to clean points every other trip...i replaced coil and points ...still cleaning!! ...outside of converting to electronic ign , is there anything else i could try??<br />Thanks for any imput

 

[Boatin Bob]

Re: voltage to coil

Did you also replace the condenser with the points?

 

[chuckz]

Re: voltage to coil

You're either measuring wrong or have some serious grounding problems. The points are suppose to ground the coil. With the points closed the voltage on the points side of the coil should be zero. With the points open the voltage will be the same on both sides of the coil.<br /><br />Conventional ignition systems use a ballast resistor. In the run position you should have approximately half of the battery voltage at the input to the coil. The only time you have full battery voltage at the coil is when the engine is being cranked.

 

[rodbolt]

Re: voltage to coil

also are you cleaning the point contact area with a non-oily solvent? and check the continuity between the point mounting surface and the block. occasionally it will fail. should be less than .5 ohms.voltage will depend on if the points are open or closed and where you test the system.