Weird stuff in my 6 to 12V Conversion....

Last week, when I couldn't get my 46 Merc truck, 6V positive ground, started, I jumped it with a 12V battery and ZOOM! she cranked right up. I then finally decided to do the 12V Negative Ground conversion - but something went wrong along the way....

Following a couple different instruction threads, along with the advice of my local starter/alternator repair shop owner, I purchased a 1 wire Alternator (Delco 10SI type) and 2 ballast resistors. I removed the Generator and it's wires and taped them off. Mounted the new Alt in it's place and ran a 10G wire from the lug to the positive side of the battery (at the solenoid). I put one ballast resistor in line from ignition to the (+) side of coil and the other in the main gauge/dash power line.

I then put in a freshly charged 12V battery, positve to the solenoid and Neg to the block and firewall. Then I tightened everything up and flipped the ignition switch. All the gauges worked. But - when I pushed the start button, the starter barely moved, then it stopped moving and the solenoid started rapid cycling (the tell-tale "dead battery" sign). So, I hooked up another battery - same deal. The voltmeter reads $13+ volts. I hooked up a starter charger, jumpers to each side of every main wire, even used a screw driver across the solenoid - everything....still nothing.

One more oddity: the instructions say to "change" the ignition wire to the (+) side of the coil - but it already WAS on the (+) side, with the coil wire going to the (-) side. The truck has been running like that for years - with a 6V positive ground system. What up with that?

So great electrically experienced HAMB'ers - can you help me? Is it the starter? The solenoid? Me??

 

Sounds like its time to get the volt meter out and check connections.get a helper to try starter and use meter to look for voltage drop

 

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First, from your pictures, I see that it seems that you only replaced the wiring that you thought you had to.

I have personally witnessed with my own eyes the result of an old battery cable. Everything from the battery to the solenoid, solenoid to starter, and engine to ground should be in as new shape. I explained this fact to a non-believer by making him change the starter cable and splitting the insulation on the old one. When he saw the corrosion inside, I explained that current flows across the surface of the wire. Without a clean, good wire, you will not deliver the necessary amps to turn the starter. It only takes a tiny bit to go from it works to it doesn't work.

Take your battery and disconnect everything. Use a jumper cable and hit the starter with it with ground connected to engine and battery ground. If it works at the starter, then go back until it doesn't work. Replace that cable.

Seriously though. Replace all that old, crappy wiring before you try to troubleshoot anything else. Even if you go thru the jumper cable method, all the other old wires are just waiting to fail. Do yourself a favor and clean up your wiring.

 

As an aside, I ran a 6V solenoid for years, I just don't get direct 12V at starting. Never had an issue while using a ballast resistor. The high amp load is to make the switch between the main terminals. 12V or 6V doesn't matter. The extra terminal allows you to send 12V to the ignition system during cranking.

 

Sounds like a bad ground from the battery to the chassis/engine block. Hook your volt meter between the starter housing and the negitive battery terminal and attempt to crank the engine.If you get a reading on the meter then you have a bad ground.

 

Subscribed.

 

This project began with a starting problem. Perhaps the same problem is still there. I agree that it sounds like a bad cable/connection to the engine. I've seen starters, solenoids, and wires fried & melted from bad grounds. I also had a similar problem from an oxidized dirty battery terminal. It looked fine. It put out enough to run gauges and headlights, but failed to start the engine.

Regarding your coil--- it sounds like someone wired it backwards and now you have it correct. The battery feed for the coil should match polarity, + for negative gnd or - for pos gnd. Most all coils will actually work either way but not perform at their best.

I'd also swap in a more modern 12V neg gnd solenoid.

 

I went back and read your post about when you originally got it. You said you ran new wires and then you smoked the wires trying to start it.

Go to square one. Take out the starter. Try to bench crank it with cables and a battery. a 6V system should have no problems carrying 12V power. Smoking cables is a sure sign there is something wrong inside the starter. I imagine you are in for rebuilding or a new starter at this point. I wouldn't be surprised if just taking it apart, cleaning it and oiling it up with new bushings would be all it would take to work. After that, if you truly fried your cables, buy some new ones and replace them.

My 52 had a locked up starter. I pulled one out of the shed, sprayed all the moving parts with carb cleaner, then deep creep. Didn't even bother rebuilding it. Swapped them out and it works 3 years later.

Final thought. Original starter should have no issues with 12V either. Don't worry about 12V doing damage to the original starter.

 

X2 check starter I'd change out the cool top. I'm pretty sure you should

 

Many of us in our Ford Social Group used this as a guide: http://www.ebay.com/gds/6-to-12-volt-conversion-1955-ford/10000000001571127/g.html Go through it step by step and see if you missed anything.You do need two things for sure, change the solenoid to a 12 volt unit and get rid of the 10 gauge feed wire replace it with a 6 gauge cable like Ford uses from the solenoid to the starter(they come in different lengths) and run it from the alternator direct to the lug on the + POS battery terminal.

 

Hi Etek,
Where in the circuit did you install the ballast for the main dash?
That could cause all sorts of trouble like you're describing. You need to install a guage regulator instead. Resistors are a bad substitute.
D

 

Think you're throwing a resisted 12v to the solenoid via the ignition switch now?

 

Thanks for all the replies gentlemen.....but electrical troubleshooting being what it is....well, instead of making guesses as to what it could have been, here's what I did (sorry for the wordiness):

I tried the battery directly to the starter as suggested (it had been on the charger all night) - nothing. Then I pulled the battery from my Galaxie and tried that directly to the starter - a couple slow rotations, then nothing. Disregarding all the good advice about bad wiring, I decided it must be the starter, so I pulled it out, intending on taking it for a rebuild.



Once out I again tried it direct from the battery (which read 12+V) and the charger - still nothing. Then I touched the jumper leads together - no sparks.... But the battery showed up to 12.8V so I popped the tops and saw it was low on water, so I topped it up and left it on the charger. Could a battery be good on volts but low on Amps?

Being a long time flat-header, I have a couple spare starters under the bench, so I pulled one with clean looking comms and brushes and tried it on the Galaxie battery - and BAM! It jumped to life. Then I tried the original starter again....it also whirred to life! WTF?

So I put the different starter and the Galaxie battery in the truck, thought about changing the battery leads - but didn't - then tightened it all up, held my breath and pushed the starter button - BAM!!! It cranked so frikken fast it nearly scared me! Horray!!

So to recap - same wires, same solenoid, same coil... different battery AND starter and I've got a modern starting engine. Here's the video. On the first 2 mis-starts you can hear how fast it cranks. Then I had to put the camera down to pull the choke and it started right up. Wow what a difference! Years of: rur....rur.....rur....comes to an end!

46 Merc starting on steroids (12V)!!

 

Cool

 

The OL' MAN gets a pacemaker and a new lease on life!

In retrospect, I did notice that the starter cable, where it connects to the starter lug, got very close to the starter body.....I wonder: could it have jumped to ground there? I have no clue, but it doesn't seem to be anything else I saw or can think of....

 

Since you went from 6 Volt pos. ground to 12 Volt neg. ground you need to reverse the wires on the back of your Amp meter.
Jim

 

Or just live with it reading backwards! I thought the temp was reading high today - but then remembered it was backwards too!

I took a load to the dump today - ran great, shut it off at the dump, started up so fast I laughed. It idled perfectly without getting warm on the 25 minute wait at the exit....then pulled well on the way out and onto the highway home.

Then it started "bucking", like it was starving for fuel, or had a massive vacuum leak, like it did last year before I replaced all the tune-up parts. When I got home it started real easy after shut off, but it had no power and would bog when I tried to gun it. I pulled in front of the shop, sprayed a bunch of WD40 down the carb and around the seals but learned nothing from that, then took the gas lines off and blew air back through them.

Tomorrow I'll pull out the vacuum gauge and take a closer look. Plus I'll rebuild the old starter for a spare.

 

Bucking sounds like vapor lock. Check heat sources near fuel lines or pump. Move or insulate.

 

Just a matter of sticking to it and getting it figured out.
Way to go!

 

I had the same problem when I did the 12v conversion on my 48 Plymouth. For the longest I thought it was the carb or fuel or even compression, I changed to a 12v condenser and and new points. Its been running fine since.

 

Both good possibilities - I'll go through it all later this week. Thanks.

 

Not sure if I've licked the bucking issue by blowing out the lines backwards, but had it running for an hour today while I switched out all the lights - with no issues.

Interestingly, the PO had someone wire in a Grote turn signal apparatus, which never worked properly. After I did all the switching to a 12V system it worked exactly as advertised! It must be a 12V signal switch - which is why it didn't work on 6V...

 

I would say that the flasher was a 12 volt unit and they won't work on 6 volts. I just wanted to give you one caution: the original 6 volt solenoids work great but remember that the starter button is hot all the time as it is putting a ground on the solenoid. If you are working on the car and anyone bumps the starter button, the car will jump if its still in gear.

 

HaHa - I learned that when I was in the kitchen looking out and saw my kid - who always plays in the Merc, bump the starter button like 5 times, each time inching closer to my overhead garage door!!! Acck!!

 

Great thread, there's some very useful info here.


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I would definitely change out the 6 volt solenoid (starter relay in my terminology) to a newer 12V unit. And then take the I terminal and wire it to the ignition coil side of ballast resistor. Then you will get 12v at the coil for easier starting.