Jacksoncage

41 Packard polarity problem

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help with polarity 41 Packard conversion have 41 Packard converted that was 6 volt positive ground and changed to 12 volt with alternator using two 6 volt batteries in series also has a lead off the batteries..not ground or starter leads..going to maybe a 6 volt area? Anyway I don’t know if it is still positive ground or negative ground as the batteries were not in it. Is there any way to tell? The old 6 volt coil is still there with armored cable running to ignition from back of coil...and does not appeared to be altered..I thought the coil had to be reversed but it does not appear that it was any help would be appreciated

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Maybe if you look closely at the battery cable ends. Positive is bigger.

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 I had a car with a 6v ignition coil that had been fitted with a 12V battery and the coil exploded, it went off with a huge bang with pieces flying in all directions.   

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This is exactly why I stay away from buying modified cars.  No one bothers to document what they have done.

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Interesting, two 6 volt batteries. Maybe the car is still 6 volts, and that is what the mystery wire is all about. Only the starter is running on 12 volts. 

 

Want to know for sure? If you have a real alternator/starter repair shop in town, remove the alternator, take it to them and see if it is positive or negative ground when they run it on the test bench. 

 

If it is a 12 volt positive ground alternator, then the car could still be positive ground 6 volt with no modifications to the original wiring (except starter).

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Do they even make a 12V positive ground alternator? Maybe they do on special order but it would be unusual. Most of these conversions use a stock Delco GM alternator. There should be some marking on the alternator  or a tag giving the specs.

 

If I had to guess without seeing it I would say 99 chances out of 100 it's a stock parts store alternator hodge podged onto the car in a half assed way. If it was a real professional job with the whole car converted to 12V  you would be able to tell.

 

The 2 six volt batteries is a clue that they hodge podged it trying to make the car half six volt and half 12 volt.

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Disconnect any wiring to the alternator. Using jumper cables go from the battery straight to the alternator. Take the negative to the alternator housing. And tap the positive to the output terminal on the rear of the alternator. If you do not get any sparks it is a negative ground alternator.

 

Edited by certjeff1 (see edit history)

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That test seems a little rough on the internal diodes. They will short with that much current going through them.

 

To make a positive ground alternator, just reverse the diodes inside. Now that being said, the 6 main diodes are easy to reverse, but the trio and the voltage regulator? Maybe not.....  Depends on manufacturer of the alternator.

 

Here is a Delco that has been changed:

 

https://brillman.com/product/12-volt-one-wire-alternator-63-amp-positive-ground/

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21 hours ago, Jacksoncage said:

Thought of that they are not tks though

 

If the battery cable lugs are identical in size it may be that they have never been hooked up and the seller was confused as well.

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Thanks for all the help.. I am going to work on the car tmrw and get back to you..there is also a 2-4 gauge running from battery side of starter to the regulator box where it’s tied into two other wires exiting the regulator...if the alternator can be identified as positive or negative ground that would be my best way of knowing...I’m assuming its negative ground ....under the dash is all required..very little old wiring existing at all...the is also,an installed series of modern fuses boxed and mounted on inner fender and there is a new battery voltage gauge installed on the dash...so I think,it is negative ground but the ignition coil is definitely 6 volt and does not looked disturbed so the negative backside of coil is running to ignition

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The new voltage gauge might give you a clue to if they have kept it +ve ground or changed to -ve ground.

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On 2/4/2019 at 1:04 AM, Rusty_OToole said:

Do they even make a 12V positive ground alternator? Maybe they do on special order but it would be unusual. Most of these conversions use a stock Delco GM alternator. There should be some marking on the alternator  or a tag giving the specs.

 

If I had to guess without seeing it I would say 99 chances out of 100 it's a stock parts store alternator hodge podged onto the car in a half assed way. If it was a real professional job with the whole car converted to 12V  you would be able to tell.

 

The 2 six volt batteries is a clue that they hodge podged it trying to make the car half six volt and half 12 volt.

You were right! After long day today this is what I’ve learned...it does have what appears to be standard Delco positive ground alternator...so I hooked up battery cables  negative ground. After changing some fuses and full battery charge most things are getting power...starter was not working well...determined I had really bad ground voltage from old cable...changed that out and getting great starting power now.  Points were damaged beyond repair..so got new points and condenser and hope to install tmrw and pray for spark...getting gas to carb. Bad news is radiator fluid dripping out of the water pump somewhere behind pulleys when turning over engine maybe dried out gasket? Also I think the firing order is out out of sequence with what I see on spec wiring diagram. Could that be possible looks like two are in the wrong spot...I know it ran 20 yrs ago but somebody may have messed up the sequence as the distributor is original Autolite. Any help with this and points gap would be great..glad I came to this forum!!

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Very common for plug wires to get mixed up especially on an inline engine, I have done it myself.

 

1941 Packard - Spark plug Y4A - Gap .028 - Point gap .020 (six) .017 (eight) - Dwell 35 (six) 27 (eight) -Firing 153624 (six) 16258374 (eight) -

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A good Packard does not need a conversion to 12 volts.....hackers.

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Thanks again...this diagram is much clearer than the one I have....I will keep posting progress with the advice given..this is a very helpful forum!

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Am I reading that the alternator is positive ground and you hooked your battery up negative ground?

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No that’s incorrect alternator was negative ground...standard...I meant it was being fed through positive for power...thanks though that would not have been good!

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18 hours ago, Rusty_OToole said:

Very common for plug wires to get mixed up especially on an inline engine, I have done it myself.

 

1941 Packard - Spark plug Y4A - Gap .028 - Point gap .020 (six) .017 (eight) - Dwell 35 (six) 27 (eight) -Firing 153624 (six) 16258374 (eight) -

 

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Got new points and condenser in today...started right up...seems to be running fine but the firing sequence is incorrect on 4 of the plugs? Should I correct them or leave it alone. Also I can tell,the clutch is frozen...any ideas on that issue! I can forcefully get it in gear but it jumps with clutch pedal depressed..I have been keeping it in neutral while running engine...also,the radiator fluid that was leaking seems to have stopped once running..I filled it up before trying to start it and no,leaks now? Thanks for all the help

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Radiator should be filled to not much above than top of the core when you look in the filler neck. It will just eject the rest when it gets hot.

 

If fire sequence is wrong, fix it! Or find out if it is something else. Watch it running in the dark - you may have leakage to earth out of the plug wires and that will show in the dark.

 

Frozen clutch: start it in 1st gear with clutch down and all brakes on (so it doesn't go through the end of the garage). This may be enough to crack it free. Find the inspection covers and see if the clutch surface on the flywheel is rusty or coated in oil. If oily, the clutch will have to come out.

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Clutches sometimes get stuck in long storage. If there is an inspection cover on the bottom of the bellhousing take it off and have a look. Have someone hold the clutch pedal down or prop it down with a stick. Slide a knife blade between the clutch plate and flywheel and between the clutch plate and pressure plate. For a thorough job turn the engine a bit and do this 3  times. The clutch will come free. It is surprising how little rust it takes to glue a clutch together.

 

I'm surprised the engine runs if the firing order is wrong. I would at least try changing it to the correct order.

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