67' instrument cluster re-install

[Gerard F.]

Re: 67' instrument cluster re-install

Don,

I thought I'd let you know that I tested out today, the new AC Delco temperature sender, "made in USA" (from Zip), with the new AC Delco temp gage (Made in Taiwan, and they seem to be accurate to my canning thermometer taped to the upper radiator hose.

The new gage looks like the original, although you have to take out this little resistor in the mounting when you mount it.

I also went on the Lectric Limited website and ordered their new sensor and a bulb set. We will see how that sensor works, and where the bulbs are from.

Jerry Fuccillo

[Donald T.]

Re: 67' instrument cluster re-install

Keep us posted on what you find out!

[Donald T.]

Re: 67' instrument cluster re-install

Keep us posted on what you find out!

[Jack H.]

Re: 67' instrument cluster re-install

If you're talking about a thin rectangular solid component that's a wire wound resistor which installs between terminal posts on the back of your gauge, that's the factory original calibration resistor for the temp gauge!

Early gauges (up to the mid-60 era) were built without the pointer needle installed. They were hooked up to a precision final calibration/test fixture that applied controlled voltage and current. That caused the pointer shaft to rotate to a specified position and the cal operator installed the pointer needle to point to a pre-defined position in the red-line warning area at the top of the dial. Now, you had a calibrated temp gauge because the only real concern of the system's design was that it be accurate at the HIGH END of the scale (impending engine overheat/thermal runaway)....

Later gauges were assembled with the pointer needle installed after the face plate was attached with the needle pointing to a specified position at the LOW end of the dial. They were connected to the final gauge calibration machine and the test operator picked from a bin of precision wire wound resistors and installed the appropriate resistor onto the back of the gauge (a 'shunt' circurit across the guage's internal load deflection inductor) to force a predefined needle point position at the HIGH END of the scale.

If you've removed this factory hand-selected precision resistor from your temp gauge (it can also act as a sacrificial 'fuse' to protect the gauge in the event of a temp sender dead short circuit condition), then you probably threw out the baby with the bath water in terms of meter accuracy. Seems to me like too many folks concentrate on tinkering with their temp sender trying to 'cherry pick' a good one and/or 'tailor' it with series/parallel fixed resistors we really need to start by questioning whether the temp gauge is in/out of calibration to start with....

[Jack H.]

Re: 67' instrument cluster re-install

If you're talking about a thin rectangular solid component that's a wire wound resistor which installs between terminal posts on the back of your gauge, that's the factory original calibration resistor for the temp gauge!

Early gauges (up to the mid-60 era) were built without the pointer needle installed. They were hooked up to a precision final calibration/test fixture that applied controlled voltage and current. That caused the pointer shaft to rotate to a specified position and the cal operator installed the pointer needle to point to a pre-defined position in the red-line warning area at the top of the dial. Now, you had a calibrated temp gauge because the only real concern of the system's design was that it be accurate at the HIGH END of the scale (impending engine overheat/thermal runaway)....

Later gauges were assembled with the pointer needle installed after the face plate was attached with the needle pointing to a specified position at the LOW end of the dial. They were connected to the final gauge calibration machine and the test operator picked from a bin of precision wire wound resistors and installed the appropriate resistor onto the back of the gauge (a 'shunt' circurit across the guage's internal load deflection inductor) to force a predefined needle point position at the HIGH END of the scale.

If you've removed this factory hand-selected precision resistor from your temp gauge (it can also act as a sacrificial 'fuse' to protect the gauge in the event of a temp sender dead short circuit condition), then you probably threw out the baby with the bath water in terms of meter accuracy. Seems to me like too many folks concentrate on tinkering with their temp sender trying to 'cherry pick' a good one and/or 'tailor' it with series/parallel fixed resistors we really need to start by questioning whether the temp gauge is in/out of calibration to start with....

[Gerard F.]

Re: 67' instrument cluster re-install

Honest, Jack,

The instructions with the new gages tell you to discard the resistor between the poles, and that the gage is internally wound for greater accuracy. But me, I save everything, the old gage and the resistor, I still have.

The old gage worked OK until I sent the speedometer and tack out to be restored, and ordered overlays for all the small gages. The overlay instructions for the reinstallation were to put 12 volts on it, and then reinstall the the needle to a predetermined low position. This probably burned the resistor, as it never worked properly since then.

I would just love to have the circuit diagragm for the temperature circuit with the resistance values to analyze. Although I'm a civil engineer, my minor was electrical engineering (before they called it electronics engineering with computers). With the right equipment, the circuit diagram, and a slide rule(which I still have) I could be the NCRS temperature gage sender/gage consultant.

Seriously, if the right combination of sender and gage works (as tested with the thermo taped to the radiator hose), it works. But I'd still love to have that circuit diagram.

I'm interested in the fuel gage circuit also, as I'm having trouble with it now. I replaced the gage, and now planning to replace the sender in the tank. Everytime I plug in the tank sender, it burns a fuse. It also knocks out the temperature gage as it is on the same circuit.

Jerry Fuccillo

[Gerard F.]

Re: 67' instrument cluster re-install

Honest, Jack,

The instructions with the new gages tell you to discard the resistor between the poles, and that the gage is internally wound for greater accuracy. But me, I save everything, the old gage and the resistor, I still have.

The old gage worked OK until I sent the speedometer and tack out to be restored, and ordered overlays for all the small gages. The overlay instructions for the reinstallation were to put 12 volts on it, and then reinstall the the needle to a predetermined low position. This probably burned the resistor, as it never worked properly since then.

I would just love to have the circuit diagragm for the temperature circuit with the resistance values to analyze. Although I'm a civil engineer, my minor was electrical engineering (before they called it electronics engineering with computers). With the right equipment, the circuit diagram, and a slide rule(which I still have) I could be the NCRS temperature gage sender/gage consultant.

Seriously, if the right combination of sender and gage works (as tested with the thermo taped to the radiator hose), it works. But I'd still love to have that circuit diagram.

I'm interested in the fuel gage circuit also, as I'm having trouble with it now. I replaced the gage, and now planning to replace the sender in the tank. Everytime I plug in the tank sender, it burns a fuse. It also knocks out the temperature gage as it is on the same circuit.

Jerry Fuccillo