Switched back to points

chris78260

Cadet
Joined
Jul 26, 2009
Messages
8
Can someone help me out with voltage problem with 78 mercruiser 260. I put new points & condenser in today and hooked resister wire back to pos. side of coil with no internal resistance. Started engine to check volts before setting time got 10.5 with neg terminal of meter to ground on motor and 11.5 with ground to neg. post of battery. So then i tried the internal resistant coil i had from the electronic igintion i switched out and got even higher readings??? Both coils got very hot when having problems with pertronics iginitor maybe they are both bad or my resister wire is bad. If resister wire is bad should'nt the internal coil drop voltage. Maybe try new resister coil. I bought inline resister but hooked it up to 12v wire i ran from igintion and did'nt drop volts at all. 10.5 is too high for points from what i have read on other posts should be no more than 9 volts. Thank you for any help we had this boat for 4 months and never had it run for more than 30 min. at a time Does ran good for 20 to 30 mins. though
 

xltier

Chief Petty Officer
Joined
May 20, 2004
Messages
636
Re: Switched back to points

Can someone help me out with voltage problem with 78 mercruiser 260. I put new points & condenser in today and hooked resister wire back to pos. side of coil with no internal resistance. Started engine to check volts before setting time got 10.5 with neg terminal of meter to ground on motor and 11.5 with ground to neg. post of battery. So then i tried the internal resistant coil i had from the electronic igintion i switched out and got even higher readings??? Both coils got very hot when having problems with pertronics iginitor maybe they are both bad or my resister wire is bad. If resister wire is bad should'nt the internal coil drop voltage. Maybe try new resister coil. I bought inline resister but hooked it up to 12v wire i ran from igintion and did'nt drop volts at all. 10.5 is too high for points from what i have read on other posts should be no more than 9 volts. Thank you for any help we had this boat for 4 months and never had it run for more than 30 min. at a time Does ran good for 20 to 30 mins. though

you have to have the resistor in service for it to show a drop.has to be a draw on it.early mopar vehicles used a firewall mounted resistor for the points.9if i remember correctly it ran 9 1/2 volts running.full voltage during cranking for better starting.
 

chris78260

Cadet
Joined
Jul 26, 2009
Messages
8
Re: Switched back to points

Thanks for the reply xltier can you tell me if the ceramic resister i have needs to be mounted on something for grounding purpose it has a hole in the middle of it to bolt it somewhere or is that just to keep it placed somewhere Do i run it on a 12v igintion wire to coil and do away with old resister wire just hook up 12v when cranking wire with it
 

chris78260

Cadet
Joined
Jul 26, 2009
Messages
8
Re: Switched back to points

Hooked up inline resister and get less voltage with resister wire on about 1 volt less with wire resister than inline but volts are jumping around between 6 and 10 maybe timing needs to be set after installing new points before i get a steady reading
 

gadget73

Petty Officer 1st Class
Joined
Jun 20, 2009
Messages
308
Re: Switched back to points

No, its not grounded. The screw hole is just for mounting.

Usually there is a wire from the + side of the coil to the I terminal of the starter solenoid which provides your full 12v while cranking.

If you have an ohm meter, you can check the resistor wire. Put the meter on the ohms scale, and see what it shows. It should not read 0 ohms. If it does, what you have is not a resistor wire, but just a piece of wire.

Also, and I'm not trying to be a jerk here, but it would be a bit easier to work out what you're asking if you add some punctuation.
 

WizeOne

Commander
Joined
Mar 23, 2008
Messages
2,097
Re: Switched back to points

....Also, and I'm not trying to be a jerk here, but it would be a bit easier to work out what you're asking if you add some punctuation.

Come on gadget. Get with the times! chris is probably just using text speak.:p

Seems to be the wave of the future!:eek:
 

Maclin

Admiral
Joined
May 27, 2007
Messages
6,761
Re: Switched back to points

Current kills points, not the voltage. Keep that in mind. You need to run whatever resistance the coil "wants". If it is close in specs to an OEM coil then use the length of resistor wire specified and you should be fine.

The ballast resistance is just that, ballast, for the opposite "side" of the coil from the points, keeps the circuit balanced in regards to current draw. The ballast resistance is to keep the coil from drawing all the current available to that circuit and subsequently burning out anything that cannot take as much as it can, especially as things heat up and create more resistance. Coils also produce reluctance when in use which is the resistance of a coil when energized, the magnetic lines produced add more resistance to the circuit than just the resistance from the windings. This changes by workload and heat, and once again the ballast resistance is there to act as a flywheel to keep it from running away.

If it is an aftermarket coil then use whatever ballast the manufacturer has specified for their coil. I think you should be fine using a coil with internal ballast as long as the manufacturer specified very specifically that it can be used in points systems. In this case replace the resistance wire with appropriate gauge standard copper.

The ceramic ballast resistor is designed to be mounted flat on something with nothing else around it within an inch or so, and whatever it is mounted to needs to be able to get hot and act as a heat sink to a degree. It needs some air around it also, they get very hot.
 

chris78260

Cadet
Joined
Jul 26, 2009
Messages
8
Re: Switched back to points

Thanks Mac I put new coil mercruiser non-resistance and hooked up resister wire

Now I'm reading 9.5 to 9.8 at pos. side of coil and 13.4 at battery both readings with engine running, so i guess the wire is working properly

Ran for 20 mins. on muffs coil did not get hot, so I'll take it out and see how
it goes

Hey WiseOne you picked the wrong title, should be WiseA..
 

WizeOne

Commander
Joined
Mar 23, 2008
Messages
2,097
Re: Switched back to points

....
Hey WiseOne you picked the wrong title, should be WiseA..

If WizeA's believes in speaking and writing the Kings English with some amount of propriety, then yes, your title fits.:p
 
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