Generator wont kick in until 1500 rpm's.

[Mart]

I've been looking at the charging on my 33. It's running 12V. I fitted a generator made up from what I thought was a later 12V generator with an 8ba style front plate and pulley.

I have tried two different regulators, and the generator does not pull in until 1500rpm.

I cleaned the contacts on the regulators and the generator, and cleaned the commutator and brushes.

Could it be that the generator I thought was a 12V unit could be a 6V unit?

Is there a way of telling if an armature is for 12V or 6V?

How about the field coils, is there a way of telling if they are 6V or 12V?

I have tried rigging separate grounds from the generator and regulator to battery ground, with no effect so I presume the existing grounds are ok.

Any ideas?

FWIW my roadster starts charging at just above idle, I don't have to rev it to get it to pull in.

Mart.

[cmbrucew]

Mart
Armature does not care. Field windings are thicker wire for 6 volt. What is the size of your gen pulley?

Bruce

Works good
Lasts long time

[Bruce Lancaster]

Reading voltage regulator adjustment instructions really hurts my head...and all my coffee from this morning has worn off...but here are some fragments I partially understand. Cut in spec is between 6 and 6.6, not applicable to you but hook a volt meter into the arm wire if you can and look for above 12 to see what the gen is doing while you mess around.
adjustment is by bending the spring support...same sort of tool as point aligner or just improvise. Increasing spring tension causes cutout to close at HIGHER voltage, decrease is what you want, causes cutout to close at LOWER voltage. Be careful as adjustments are tiny, be careful not to ground anything, and be aware that result will be a bit different with lid back on and everything warmed up.
Please note that I accept no responsibility for fiery death, incinerated car, or smoke!

[Mart]

What's wierd is that my multimeter is a waste of time when the engine is running. I can't read any voltages, they are all over the place. Man that ignition is NOISY!

Mart.

[Bruce Lancaster]

Is it digital? You need analog type with vibrator/point kinds of things. If no numbers, try just decreasing the tension a tiny bit and see what happens. Record it on youtube in case it gets exciting.

[Mart]

Sponsored Links (Register now to hide all advertisements)

LOL Bruce, you're priceless!

Are we talking about the one set of points that are normally open? or the two that are normally closed?

What worries me, is that if I close the normally open ones with my finger, they stick shut and the ammeter shows a big negative charge.

I will play about with it a bit more tomorrow after work, it's a bit late here now to be messing around with poorly silenced V8's!

Mart.

[Bruce Lancaster]

cutout relay is the one at the bat terminal...bend the spring on movable arm. Yes, stop work if it's late...all the ambulances and fire engines will wake the neighbors!

PS...if you smell acrid smoke, call the fire department; if you smell burning bacon, call for an ambulance. This is precision work requiring the proper experts...

[B-O-B]

Mart try turning on the headlights & see if the gen kicks in @ just above idle. My 34 does that somtimes & when I turn on the headlights it will start charging & work ok as long as the engine is running. You might need to install a idiot light . 6 V on my 34 tho.

[Mart]

Well I tried tweaking the cut in, it kind of worked a bit then it stopped charging completely.

I fitted the known good generator off Old Rusty, and that didn't work either, so I fitted the other voltage regulator and that combo works perfectly, cutting in just above idle, and charging strongly.

I laid out 5 generators, some of which I presume are 12V, and some presumed 6V.

The 6V ones measure approx 4 ohms through the field windings. The "12V" ones seen to come out at 8 or 9 ohms.

Funny thing is, the known good one that charges really well checks out at 18 ohms.

I can't work out quite what is going on, should a 12V one be 18 ohms or so, and all the others are 6V?

I don't think so. maybe the higher reading was due to it just having run and being warmer? It didn't feel more than slightly warm to the touch though.

One thing I can see, is that the pulley on the good one is a bit smaller than the others. That must help.

Not really any wiser.

Mart.

[B-O-B]

Do you have a growler to check your armature. I would think as long as the field windings are not grounded out they should be OK. Do you have any glyptal (red insulating varnish type paint) Check the brushes & bearings & brg housings & if all are ok you might turn the commutater & under cut between the bars spray windings with glyptal & put er back together should be ok

[OLD...BILL]

MART: So you have a good working regulator on your "Roadster" ... lets transfer it to the 33... donot open it up, just move it over.... no re-polarizing.... and give it a try.?? I hope you have a dash mounted amp meter, or ever better a voltmeter,( add on )...we-er not going maximum smoke here.....
AND the other thing, " I can't get a voltage reading when running " anywhere, there all over the place. That tells me you have a floating ground. talk about pulling you hair out, chase one of those for a whille... ie ... body not grounded to frame, engine to frame, dash to body.... to much nice new paint in places... OLD....BILL

[habbott]

Had this problem before best fix to this problem is to replace pulley to a small size to increase the rpm of the generator. I end up making one to the size I wanted.

[Bruce Lancaster]

Old Bill has an excellent point, and a good rule to follow is that any electric problem you cannot figure out is on the ground side...
KILL the overall ground issue, and this will pick up preformance of the whole system:
Run ground wire from G post on gen to base plate of regulator, then run wire from there to a big ring terminal bolted into battery ground to car location.
ALL old Fords have ground problems, the junkers from rust and dirt, the restored ones from way too much paint.

[koates]

Hi there, STOP messing around with it. You could do more damage and have more problems then when you started. Find an older auto electrician (over 60 ) who knows these units. An analog test set with voltmeter and ammeter is required to set these voltage regs up.(Digital multimeter throw it away for old cars). The cut out, voltage regulator and current regulator have VERY SPECIFIC adjustments and settings. They have to be set right. The generators could be a mix up of parts and have to be tested electrically and with a trained eye. The field coils in particular have to match the cars voltage otherwise the voltage regulator contacts will burn out. Ive been working on this stuff for 50 years, am in AUSTRALIA and not comming over to help you. Get an expert !! Regards, Kevin.

[Mart]

Yes, koates you do have a point.

Here's what I did.

I put the good working generator off my roadster (Old Rusty) onto my coupe, with the regulator I had not messed about with, and it behaves well, charging nicely at just above idle.

I fitted another generator that I had converted to 12V some time ago, and put that on the roadster, with the same regulator it had before, and while not picking up the charge just off idle, it does start charging ok, and I'm sure will be ok.

It performs better than the generator I was trying to use on the coupe.

I am hoping to get the registration docs through very soon and be able to drive the coupe on the road for proper shakedown testing.

Mart.

[rotorwrench]

Some of these old generators hold a residual magnetism in the field pole shoes better then others. When the gen starts to turn the residual is usually what pulls the cut out to close the charging circuit. You can only flash the field so many times to get that residual magnetism to its max. Whatever gauss it holds is all it will ever have.