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Discussion Starter #1
I picked up a ss cluster for my wagon and I would like to test the gauges so I know if they work proper or if it needs to go in for repairs I do know I'm going to change the speedo that's in the car for the one in the ss cluster cause it's nicer not sure if i want a clock or a tach, so I'm not sure what's going in the center hole yet.
So I need to test the gauges here's what I know and what i don't know

Oil gauge plug hose in start engine should should show pressure if it works, or leak if it's broken.

Temp gauge not sure cause I don't have the right sending unit yet. Is there any way to bench test this gauge without the proper sending unit?

Fuel gauge I have a 5/16 sending unit from classic industries not sure on the ohm rating what will let me know if the gauge works?

Ammeter is there a bench test for this gauge I know it needs a shunt? Not sure what that does tho, I am watching the ammeter to volt meter swap and may go that rout any and all help is appreciated thanks
 

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what ever you do DON'T hook up the amp meter gauge straight to the battery. You will smoke it. There is a post going around right now on switching it over to a volt gauge.
 

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The simplest/safest caveman-style way to see if the gauges are dead is to tape a few D-cell batteries together end to end. 4 will give you 6 volts, 6 will get you 9v, and 8 will get you 12v.

Just tap the leads to the gauge lugs quickly, the needle will move...or not. Try reversing the leads if you don't get any reaction.
 

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Discussion Starter #4 (Edited)
The simplest/safest caveman-style way to see if the gauges are dead is to tape a few D-cell batteries together end to end. 4 will give you 6 volts, 6 will get you 9v, and 8 will get you 12v.

Just tap the leads to the gauge lugs quickly, the needle will move...or not. Try reversing the leads if you don't get any reaction.
Ok tried that and temp gauge jumped and fuel gauge jumped haven't done the oil pressure gauge yet. also didn't do the ammeter cause i don't want to toast it.
I am looking at the wiring diagram for the ss gauges and it shows the positive wire 12ga from the battery going to shunt then from other side of the shunt also 12ga wire going to horn relay then from each side of the shunt there are 18ga wires going to the ammeter. 18ga wire seems kinda small if all of the power from the battery is running through it, since it's a wagon I would have to do all of the wiring, would a larger wire to the gauge be better or would it make it unsafe . So here's where I'm stuck I'm going to get the gauges recalibrated, cleaned up and add a shiftworks tach. Im not sure if i should I get a shunt ($50) and keep the ammeter (possible safety issues ) or have it converted to a volt meter ( much more money ). I may do the conversion myself but I wouldn't be comfortable cutting on the ss cluster
 

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Ok tried that and temp gauge jumped and fuel gauge jumped haven't done the oil pressure gauge yet.
The oil pressure gauge is mechanical. You will need some compressed air or something to test that.

also didn't do the ammeter cause i don't want to toast it.
You can safely test the ammeter using the D-cells. I just tried it on mine (using 8 cells even) and the needle waggles in the appropriate direction depending on which way it's hooked up. Do NOT hook it up directly to your car battery.

I am looking at the wiring diagram for the ss gauges and it shows the positive wire 12ga from the battery going to shunt then from other side of the shunt also 12ga wire going to horn relay then from each side of the shunt there are 18ga wires going to the ammeter. 18ga wire seems kinda small if all of the power from the battery is running through it, since it's a wagon I would have to do all of the wiring, would a larger wire to the gauge be better or would it make it unsafe .
Short answer:
For the stock setup, use the 18ga wire.

Long answer:
MOST of the current goes through the 12ga wires and the shunt. Some small percentage of the current goes through the 18ga wires, so not everything is going through there. That percentage is what the gauge registers. The ammeter circuit is based on knowing that percentage, which comes from knowing the resistance of the shunt, and knowing the resistance of the ammeter...and the wires that connect it. If you change the wires, you change the resistance, and the meter won't read accurately. (Admittedly, the difference in the reading would be pretty small, and even at that the gauge isn't labeled in amps, just C and D, so you'd be hard-pressed to tell the difference anyway with no reference points...)

The original alternator was putting out 61A max, so I'd assume that's about full scale on the meter. (Based on the gauge labels on other GM products of similar vintage, that makes sense as they often say +/- 60)

The problem is...a modern alternator can easily put out 130A or more, which under extreme circumstances could peg the ammeter and damage it even if it is installed as per the factory intended

So here's where I'm stuck I'm going to get the gauges recalibrated, cleaned up and add a shiftworks tach. Im not sure if i should I get a shunt ($50) and keep the ammeter (possible safety issues ) or have it converted to a volt meter ( much more money ). I may do the conversion myself but I wouldn't be comfortable cutting on the ss cluster
Verifying the gauge calibration is as simple as using a known input and watching the results. Get a temp sender, hook it up to the gauge with a car battery, and drop the sender in boiling water (or some other known temp) and see what reading you get. Similarly, you can check the gas gauge using a tank sending unit and moving the arm up and down to see that the reading on the gauge changes appropriately. The ammeter is tougher to test beyond the D-cell test without actually hooking it all up as it was intended however.

Mine? The gas gauge works, the oil pressure gauge works, the temp gauge works, and...I never bothered to hook up the ammeter. I could, but...never really had a great urge to do it.

It's not *that* hard to get the instrument panel out, so...I'd say clean it up, hook it up, and roll the dice. Worst case you take it out again and fix whatever is broken. Then again, I'm a cheap [email protected]#(rd. :D
 
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