Constant Voltage Regulator

[kevin_tbird]

My bench setup now has a 12v motorcycle battery that is putting out 12.26v. The amp draw on the circuit is 1.54 amp. Voltage measured at the CVR ign terminal is 12.15v. Output voltage from the CVR is about 0-11.x volts. The fuel gauge will only drive to 3/4 full. The temp gauge will drive to the highest setting

I suspect I need to adjust the fuel gauge upper limit on the back of the gauge.

Kevin

[simplyconnected]

You're moving in the right direction. At least you got a battery with enough power to sustain 12-volts.

You know that the 1.5-amps is dumped to ground through the bi-metal contact. Gauges don't need that much current but heaters do.

Do you have the sending units in series with their gauges, or are they shorted to ground? If you have a gauge pegged, don't leave it there for very long.

Now, we're back to 'current' and 'duty cycle'... If you connected a constant six volts to the fuel gauge (without a CVR), where ever the needle lands, that's your 'average six volts'.

Adjust your CVR to that value when it is connected to the motorcycle battery, to emulate an 'average of six volts). After adjusting the CVR, you can adjust the gauge to full scale.

[kevin_tbird]

I am using a potentiometer to adjust resistance in the circuit and it is connected in series with the gauge. One ground runs from the battery to the pot and then to the gauge.

The other ground runs from the battery to the CVR. Are you saying that the pot should have the third terminal run to ground also?

The CVR duty cycle is good I think. I get the same gauge reading with 6v direct as I do with 6v average from the CVR.

[simplyconnected]

...Are you saying that the pot should have the third terminal run to ground also?..

No, then it would act as a voltage divider. I'm surprised you found a pot large enough to simulate your float.

If you get the same gauge reading using NO CVR and a six volt battery, as well as using the CVR with a 12-volt, you should be ready to adjust the fuel gauge to full scale.

BTW, if you have the original CVR, what are the mounting hole centers, and what size holes does it have?

[kevin_tbird]

I'll send measurements on the orig CVR shortly.

When adjusting the fuel gauge it has two sticky spots during the sweep. When it reaches just above 3/4 full I have to gently tap the case with a screwdriver to get it past that spot. When sweeping down at the half full mark it catches, jumps an 1/8 tank up, and then resumes the downward sweep.

Question for both the fuel gauge and temp gauge. When empty/cold should the needle be at the bottom of the range (the dots at the end of the bars) or all the way to the left (closer to the E/C)?

Also, does anyone know what a fuel sender resistance should be at full and empty. Same question for a temp sender at cold/hot (a chart would help here).

Thanks

Kevin

[YellowRose]

Constant Voltage Regulator

As posted at the beginning of this thread, I was told this. I do not know if this is true or not, but a mechanic told me that when you have the ignition turned on and the gauges indicating properly, do not expect the fuel gauge pointer to be on the E when the tank is empty or on the F when it is full. Instead it should be sitting on the lowest mark for Empty and the highest mark for Full, not the letters. The same thing applies to the Temperature gauge. However, I do not know how factual this is. As for adjusting the readings on the gauges, try to set them at the lowest point you can for Empty or Cold, and the highest point you can get it for Full or Hot. If you can do that, then you will have some readings that you can trust hopefully. I hope this helps.

Dave and I have been wondering what an original OEM CVR really looks like. So we looked at pix that Alexander posted when he wrote his article regarding checking and adjusting the gauges. He said that the CVR unit is usually mounted on the backside of the instrument panel, mounted and grounded to it. He also said that he found some CVR's mounted/grounded to the dash frame support. What we notice is that the one mounted to the back of the instrument panel has mounting studs to the left and the right side of the unit. Joe Johnston posted a pic of what he said were original CVR's showing no mounting tabs like that, but with one single mounting tab at the top of the unit like mine was when I first replaced it. The ones I bought from Bird Nest also had the same single mounting tab and not the two on the sides.

So my question is: Is the instrument panel mounted CVR unit the OEM one or was Ford using two different units? If so, why? Why would they mount one on the back of the instrument panel on some Tbirds and then sometimes mount them on a metal dash support strip instead like mine was? (However, I do not know if mine was an original CVR unit). Maybe the latter is the way they were mounting them in the '58's and '59's and then in 1960 someone decided to mount them on the back of the instrument panel?

Does anyone have any pix of a '58, '59 and/or '60 Tbird showing their CVR unit in place, that they KNOW is an original OEM unit because they have had that Tbird since the day it left the factory? And they know it has never been replaced? If you do, please post some pix of it.

Here are three pix. The first one is the one that Alexander posted showing a CVR unit mounted to the back of the instrument panel. The second pic is one that Joe Johnston posted showing two CVR units that he said are originals. The third one is what one looks like today, if you buy it from Rock Auto, or Birds Nest or other Tbird parts houses, as posted by Dave. As you can see by the latter two, neither of them have mounting tabs on the side to mount it to the back of the instrument panel... Somewhere along the line, something got changed...

[Guest]

Ray; I bought my 60 bird from the origional owner and it has the cvr mounted on the back of the instrument panel like the one in Alexander's picture. Two tabs on the ends and mounted with two screws. I know it came from the factory that way.

Gary

[YellowRose]

Constant Voltage Regulator

Thanks for the reply, Gary! I see your original '60 has the CVR on the back of the instrument panel just like the pic that Alexander posted. That is good to know. I wonder if this CVR version with the flange at the top was only used during '58, '59 production? (Nope, it was the other way around!) It will be interesting to see what anyone owning an original '58, and '59 has to say about theirs. I wonder why we don't see that instrument panel mounted version offered for sale these days?

Well, I just got my answer! I just talked with Don at the Bird Nest about the history of the OEM CVR unit! Don said that in 1958 and 1959 Squarebirds, Ford was using the B7A-10804-B version of the CVR unit. That was the one with the left and right mounting tabs to mount it to the back of the instrument panel. They sold this unit as GR507 until 2009, he said, when it was dropped from production. In 1960, Ford went to the version we see today, the unit with the mounting tab at the top, B9MZ-10804-C. They sell it today as GR508, for 1960-1966 Tbirds. Sometime during the 1960 production run, Ford must have stopped using the B7A-10804-B and started using the B9MZ-10804-C. Otherwise, Alexander's and Garys '60 Squarebird and others would have had the B9MZ-10804-C in place.

Here is a close up shot of what the B7A-10804-B looks like. You can still get them new from http://stores.oksap.com/-strse-10/NE...ORD/Detail.bok (Oklahoma Starter Alternator & Parts) for $19.50! Next to that is the current 1960-1966 B9MZ-10804-C.

So now you know the rest of the story!

[kevin_tbird]

My 1960 looks just like the top right picture with one mounting tab and the mounting bracket staked to the can with two stakes. The stakes are in opposing corners - not in a straight line. We have had the tbird in our possession since it was about 10 years old.

[Joe Johnston]

Just to clarify (or add to the confusion) mine were from 63's. I have also seen another style that has 2 round contacts that are similar to those on the end of a rectangular 9V battery.

[YellowRose]

Constant Voltage Regulator

Don said that the B9MZ-10804-C was used on '60-'66 Tbirds, and I am sure Dave would say, also on other Ford/Mercury/Lincolns.

[NYsquarebird58]

The RT-Engineering IVR3 has an LED right above the Output connector that shows you whether or not it is operational. Of course, once it is installed and the instrument panel is back in place, you cannot see that LED. But if you were to take out one of your gauges, and it is mounted to one of the metal supports, you should be able to see if that LED is lit. It, as stated before, puts out a continuous 6v to the gauges. Here is a pic of it.

Ray,

My IVR3 CVR just came in from RT-Engineering, but it looks allot different than yours.

[YellowRose]

Constant Voltage Regulator

I see they left off their company name and used a magic marker to put some number on it. I see they also changed the mounting tab some and the right side IGN connector. I see the LED light is still there. Yours looks pretty much the same as mine to me. Here is what mine looked like when I bought it several years ago.

[NYsquarebird58]

Hopefully they're just cosmetic changes. As long as it drops 12 volts down to 6 volts, I am happy.

[YellowRose]

Constant Voltage Regulator

If it is a IVR3, which it seems to be, you should get a steady 6V of output. BTW, I just discovered today that I happen to have a new, unused, and good, as far as I know, B7A-10804-B CVR unit that attaches to the back of the instrument panel. I did not even know I had it. This one.