| Author |
Message |
    
thomas johnson
New member
Username: capt_tom
Post Number: 1
Registered: 04-2006
| | Posted on Wednesday, February 07, 2007 - 03:34 pm: | 
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I am lokng for info on converting my 56 graymarine Century to 12 volt pos. ground. Also looking for electroic Ing. 6 cyl 135 hp all stock 56 gray.any help please.
Thanks Capt. Tom |
miro forest
Senior Member
Username: miro
Post Number: 260
Registered: 11-2001
| | Posted on Thursday, February 08, 2007 - 05:24 pm: |
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The starters usually are positive hot, and negative ground. That will likely be your biggest challenge. You'll have to insulate the starter from the rest of the motor - not trivial. Same goes for the generator or alternator
The rest of the job is fairly well common sense ( coil, solenoid, fuses, panel lights etc).
My own practice has been to drive the starter ( a 6 V starter) with 12V and leave all the rest at 6 V.
There is an earlier post about how you do the 12 V starter with two 6 V batteries.
miro |
thomas johnson
New member
Username: capt_tom
Post Number: 2
Registered: 04-2006
| | Posted on Thursday, February 08, 2007 - 06:08 pm: |
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Miro, this is a pos grd. boat, according to the powers that be, the starter can handle 12v with no problem. The Gen is a old 3 brush job, that didn't work anyway. problem is there is no place tomount a alt. and the old gen. is a through shaft that also turns the water pump. You mentiond a solenoid, is that the starter solenoied, there are no fuses, only running and inst. lights. I still want to change to electronic ing. if possable if anyone knows where to get it.
Thanks, Tom |
Douglas J. Beattie
Member
Username: gannet
Post Number: 10
Registered: 04-2005
| | Posted on Thursday, February 08, 2007 - 08:58 pm: |
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Thomas,
I am not an electical engineer so I cannot explain why a 6v 3rd brush generator will charge 12v batteries, but it will(neg ground batteries at that). It would also seem to me that the original 6v pos. ground starter motor would not like 12v pos. gr, but it seems to love it. Van Ness engineeering in New Jersey sells a wonderful electronic ignition distributor. I can't say enough about this unit. If she won't start it has to be fuel.
I know what I've said about the charging system seems counter intuitive, but trust me it works. Your generator may need work, but once it's right (asssuming you don't have large electrical needs) you'll wonder why these thigs became extinct. I've been warned to keep the amps below 10. I also learned the hard way that if the generator is not connected to load the voltage will spike to over 300. Call Dave Van Ness he will be a big help and save you alot of trouble along the way. |
RichardDurgee
Senior Member
Username: richarddurgee
Post Number: 1414
Registered: 11-2001
| | Posted on Friday, February 09, 2007 - 09:21 am: |
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*
Years ago I converted several 6 volt 3 brush genertors to 8 volts for better starting and they worked well but always check the max output amps when adjusting the 3rd brush and keep it low like Doug says in above post or it will sling the solder out of the armature from to much heat ! make sure the cutout relay works !
This site may be helpful ?
http://www.ytmag.com/articles/artint4.htm |
miro forest
Senior Member
Username: miro
Post Number: 263
Registered: 11-2001
| | Posted on Saturday, February 10, 2007 - 08:12 am: |
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I agree on the generator.My experience was that the field current would sometimes be higher than the curent comming out of the generator. That would explain the over heating if the generator output is too high for too long.
I also found that keeping the batteries in good shape e.g. look at them regularly for electrolyte level, if they've not been use for sometime, put a charger on them overnight, also helps keep the generator current lower.
Dyke's has a very good explanation on how the 3rd brush works.
In automotive use, the engine speed varies quite a bit and the 3rd brush is used to prevent over-voltage at higher speeds and thus over-charging. On very long road trips at highway speeds, generators used to burn out because the settings were meant for city driving. Some automotive instruction mauals even suggested lowerng generator output if a long trip was being undertaken.
In marine use, the engine speed is much less variable, so you can operate with a lower charging current. The engine is , so to speak, on a long road trip always going up a steep hill.
miro
miro |
Craig
Visitor
| | Posted on Wednesday, February 14, 2007 - 12:04 am: |
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My own experience;
12 volt neg ground.
I put my ignition system together with care, and never seem to have trouble. Clean the points once a year for something to do, runs great.
I hated the generator! At an idle, the battery would discharge, at cruising speed, it would over charge. I could never get it right. I put a single wire alternator in front of the exhaust manifold (fits great in there) and have been happy ever since! (ditto with the mech vs electric fuel pump)
Now, On 6 volt systems, I never messed with the charging but I can say that they do love 12 on the starter. They start faster, spin faster, for less time which I think is actually better for the starter motor.
It appears I have modernized all but the ignition, it doesnt seem to need it?
Also that pesky rusty cast iron carb...
CP |
mitchell lowell
Visitor
| | Posted on Friday, April 06, 2007 - 07:35 pm: |
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Craig, how did you manage to mount the alternator? did you have to have a custom mount made? Does the electrical fuel pump present any problems: such as the up draft carb flooding, or leakage? How did you deal with the water pump if you removed the generator? Mitchell |
Richard A. Day Jr.
Senior Member
Username: richardday
Post Number: 490
Registered: 11-2003
| | Posted on Saturday, April 07, 2007 - 11:18 am: |
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It seems to me positive ground in a boat is liable to cause a thru hull or metalic fasteners to be destroyed if there are any leak currents in the electrical syatem.
Has anyone heard any more regarding ethanol eating up carburtors due to water separtion in long standing fuel? |
Ernie
Senior Member
Username: ernie
Post Number: 632
Registered: 01-2002
| | Posted on Saturday, April 07, 2007 - 05:37 pm: |
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I have had several carbs apart this spring because I didn't put them away properly and other than getting the dirt out I see no erosion. Last winter I put stuff away right and everything started up ok last spring. |
thomas johnson
New member
Username: capt_tom
Post Number: 3
Registered: 04-2006
| | Posted on Sunday, April 08, 2007 - 01:28 pm: |
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I also would like to here from Craig about mounting the alt. Must not be on the same old 6 cyl Graymarine because of the cast Shroud. But still want to here about it. As far as my old Gen. it got smoked the first time out after puting in 8 volt batt., no one explained about adjusting the voltage and we think the cutout was bad. We had a dead short through the cutout or gen. made system hot all the time even with key off. so for now disconn. the gen. runns on pure batt power. Still having carb adjustment trouble. Sure wish some of you engine wizards were down here in my part of Fl. Could use a good hand on this toy. |
miro forest
Senior Member
Username: miro
Post Number: 274
Registered: 11-2001
| | Posted on Sunday, April 08, 2007 - 02:21 pm: |
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I mounted a small alternator ( from a Honda car) on two in diameter posts which were drilled through to accept 7/16 bolts. I had to machine a shaft extension that was screwed onto the alternator shaft and had an OD that took the old generator pulley. THat way I did not to replace the belt, which is a pain to replace. The trick with the shaft extension was that it had to threaded down a blind hole and needed a botttom tap to do it plus it was a 12 mm metric thread for the Honda alternator. I also got a matching Honda regulator to go with it . Never had a problem after that.
I also had a creeping problem with the Zenith carb - that 6 screws that hold the two halves together would loosen slightly over several seasons and eventuially the engine would barely start. Eventually ( after about 7 years) I figured out that tightenening the 6 screws was all it took.
miro |
Lawrence T Wolfe
Senior Member
Username: larry_from_maryland
Post Number: 230
Registered: 07-2003
| | Posted on Sunday, April 08, 2007 - 04:18 pm: |
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Putting in an 8 volt battery wont fry the generator unless there is some other problem. The cutout is normally closed and opens when the current gets high. So it opens too soon if an 8 volt is installed. The big problem i see is someone will install a battery with the polarity backwards,this welds the points of the cutout closed. This puts the juice to all the parts all the time evan with the switch off. The weakest part melts first. |
mitchell lowell
Visitor
| | Posted on Saturday, April 21, 2007 - 09:22 am: |
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I have a friend that is nearly eighty five who use to install, and work on Grey Marines. He has told me that the six volt starter has no problem with twelve volts. He has stated that the windings on a six volt starter are heavier then the twelve volt starter. Due to this the six volt can be used for twelve, but not the twelve for six. I have sent my distributor to Van Ness and for around three hundred dollars it will be rebuilt, painted, and converted to twelve volts electronic. Miro, how did you drive the water pump from the alternator, or did you do something different? I am also going to use a heat exchanger for cooling and will have to run a second pump; any examples of this from any one out there? Thanks Mitchell |
michael pitman
New member
Username: skippermike
Post Number: 1
Registered: 12-2006
| | Posted on Thursday, May 31, 2007 - 12:12 pm: |
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I have photos of my 12v converted. Alt overhead mounted 100 hp. Gray Marine 100hp twins.
Hope this helps. |
michael pitman
New member
Username: skippermike
Post Number: 2
Registered: 12-2006
| | Posted on Thursday, May 31, 2007 - 12:39 pm: |
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Here is the link to my boat and engines.
Photos may help. I will take closer photos of the Alternator/Gen system install.
This was a pro shop install to marine specs.
http://www.gloucester-boat.zoomshare.com |
