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Discussion Starter #1
I recently purchased a used 69' Chevelle original Tach and Gauge Set. I would like to be sure all Gauges are working before installing in my show car. The Gauge Set includes Water Temp, Oil Pressure, Amp and Fuel Level Gauges.
I would think that I should be able to perform a bench top test with a 12 volt source and a multimeter on each Gauge individually. I need a test procedure.
Thanks for any help.
 

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Discussion Starter #3
John thanks for the ref: to wes's stuff. His section on fuel gauges is very good. And I feel confident that my fuel gauge is working fine. It's the other gauges I need help with as far as bench top testing out of the car. Wes's section on Gauges only references the installation of new/aftermarket gauges. I'm very familiar with installing the gauges. Bench top testing of original Factory Gauges is where I need help.
Any more help would be greatly appreciated
Thanks,
Brian
<BLOCKQUOTE>quote:</font><HR>Originally posted by John_Muha:
Take a peak at Wes's stuff first. See if that gets you going a little. Each gage is different. www.chevelles.com/techref <HR></BLOCKQUOTE>
 

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Well, the fuel gage is probably the only one you can check with any confidence on the bench. The others would need an accurate "standard" to see if they properly work. Something to take the place of the sensors. Coming up with something that just makes the meter move really doesn't prove that it works right. There are a couple of places out there with the proper equipment to check out your gage set. If you really want to know if they work correctly, I can dig up some addresses and numbers later and post them.
 

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Discussion Starter #5
John, In fact these Factory Gauges are very general in readout for example...
Water Temp: C//////H (Cold-Hot)
Oil Press: L//////H (Low-High)
No specific numerical dial.
So if I could in fact safely move the general indicator with say a 100 ohm potentiometer, then I would feel confident that the gauge did in fact work.
I understand what you are saying if the water temp gauge had a 100 degree mark it would be important to calibrate the gauge with a known 100 degree output source. But these gauges being general you have to " get to know" your gauges based on the fact that you know the temp is fine and where is it going to land on that specific gauge. If it deviates to far from the "normal read" at a future time then you would assume there is a problem at that time.
I have E-Mailed a couple of repair facilities but noone has offered any helpful procedures. They have only offered repair serevices.
Any other ideas?
Thanks,

Brian

<BLOCKQUOTE>quote:</font><HR>Originally posted by John_Muha:
Well, the fuel gage is probably the only one you can check with any confidence on the bench. The others would need an accurate "standard" to see if they properly work. Something to take the place of the sensors. Coming up with something that just makes the meter move really doesn't prove that it works right. There are a couple of places out there with the proper equipment to check out your gage set. If you really want to know if they work correctly, I can dig up some addresses and numbers later and post them. <HR></BLOCKQUOTE>
 

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Well, even if they move doesn't make them good. If there is a "down and dirty" way to check out gages, one of the best guys out there is Elree. Don't know if he is around.
Elree. Have an easy way to make these move around?
 

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I’ve also just purchased an old factory gauge cluster for my 69. I was about to post the same question you’ve asked. Someone out there must be able to check the gauges before installation. What would a dealer do if they had to diagnose a gauge problem? Could the sending units be hooked up to the gauges and activated?

Why Not:

Take temp unit and submerse it in a cup of boiling water.
Push on the oil pressure sensor with a known force. Pressure could be calculated based on area.
Use a resistor and Ohmmeter. Run a known current through the amp meter and see what it reads.

Would these procedures check out both sending unit and gauge, or would It just screw things up?

I’m not good at electrical problems any help would be greatly appreciated.

Thanks for the post fastss396man.
 

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Discussion Starter #9
Mike,

It has been a couple of a days as you can see since my first post. I have not received any tech help from the repair vendors I have contacted outside of this site. I have started developing my own bench test and so far I know that my Fuel Gage is properly working and that my Temp Gauge is properly working. One good find I made this morning was in an old "Chillton's Repair Manual". Under "Unit Repair" section U387 I found some very valuable info. It explains the basic difrent types of Gauges, such as Bouron Tube, Bi-Metallic, Thermal and Magnetic along with Warning Lights.

This unit refers basicaly to "in vehicle" testing and trouble shooting. However if you read between the lines and don't mind experimenting a little. It's amazing what one can do with a Multimeter a simple power source such as a "C" or "D" cell flashlight battery, a $3.00 to $4.00 100 ohm, linear taper Potentiometer (Radio Shack) an old/new Temp sending unit and some jumper wires.
I'm not talking about calibrating or repairing these gauges that's what the Pros would be for. I just want to know if they are working.
The Tach should actually be one of the easiest units to test as you can hook it up under the hood just as if you were hooking up a Dwell/Tach meter. The back of the gauge if you look real close is marked "Coil" and "12V" (volts). So you run a 12 volt source to the "12 V" connector and a lead from the - Neg side of the coil to the "Coil" connector. Start the motor and observe the Tach, You can run this test in parellel with your Dwell/Tach meter to compare readings. Just be very careful with the connectors to the other gauges not being tested.
The info from Wes's artical (see above) told me that the fuel gauge works from 0 ohms to 90 ohms. Thus the reason for the 100 ohm potentiometer. 0 ohms = empty, 45 ohms = 1/2 full, 90 ohms = Full. You can use about 4 "C" or "D" cell batteries connected end to end for your power source. The potentiometer is "linear" which means at the closed position it is 0 ohms at full open it is 100ohms and at half the turn from closed to open it is exactly half or 50 ohms. So + or - 5 ohms is close enough to see it working.
The water temp gauge is a little trickier I'll follow up later.

fastss396man

<BLOCKQUOTE>quote:</font><HR>Originally posted by mike69ss:
One more question. How would you test the Tach. I have no idea.<HR></BLOCKQUOTE>
 

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fastss396man,

Thanks for the info, it’s very helpful. I’ll have to look for my old Chillton's. I can't check the Tach like you suggest because I'm planning on putting the dash in the car before the engine goes back in. The fuel gauge check is great. I’ll try that one first. How did you check the temperature gauge?
 

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Hey guys,

I initially would have opted for you guys to send your stuff to the pros--but after reading your posts, it seems you just want to 'check them'. I have no problem with that, the only reason I suggest going to pros (and Brian, of course they won't let you in on there "secrets",--I don't reveal my restoration secrets on vintage radios since I was the one that worked on them so that is understandable) is they can virtually over-haul them.

For example guys, if you are not familiar with the tach's, the solder connections like to go on them causing intermitten/crazy/or no operation at the worst time. You can't just simply resolder them because the old materials actually "reject" solder--one must actually use little wires or jumpers and carefully reconstruct the circuits.

It's all about reliability--that's why I suggest pros.

BUT, I can respect just checking them.

You can check the gas guage as you mentioned, I always tell people to go to radio shack and get (2) 100 ohm resistors. (1) 100 ohm in series with the sending wire to ground will make the guage go past full, (2) 100 ohms in parallel will yeild 50 ohms, this in series with the sender connection on the gauge to ground will make it go to about 1/2. Ground the sender connection for EMPTY.

Temp gauage, same basic idea--but I do not know the proper ohmic range for a '69 temp gauge or whether or not the resistance increases or decreases with temp.

AMP guage does NOT register AMPS!!! in the factory guages. They are actually tiny voltmeters.

The amp guage recieves a voltage via the voltage drop found in the length of wire between the battery junction block and the horn relay. I don't know about the '69's, but for the '70-72's, about .5 volts across it will indicate 40 amps of draw thru the main 10 ga wire in the front of the vehicle that links battery power to the horn relay and all the other circuits.

Per Elree Colby:

Go to Radio Shack and get (3) equal value resistors around 500 ohms. Connect them in series to a 1.5 volt battery (C battery is fine). Connect the connections on the AMP gauage to the legs of the CENTER resistor--which will have approx. .5 volts across it. The guage should deflect to one side, reverse the leads to the back of the amp guage and it should deflect the other way, indicating a good guage.

Tach--my favorite!!

If your not set up for this forget it! Some people have gone to the trouble of getting a junk distributor, a power drill, and a battery! Spin the distributor shaft with the drill (you need to know the speed of the drill) and the Tach should inicate that speed if you EXACTLY REPRODUCED HOW IT IS CONNECTED IN THE CAR.

If you have test equipment like a signal generator, you can carefully hook it up to the tach and use that (I have not done this--another member had).

I'm actually building a circuit for bench top testing of tach's, but it is NOT ready yet.

Bottom line, if you are in doubt, send it to a pro!

Brian, Welcome to Team Chevelle!

P.S. guys, I'm only covering for John Muha while he's away on business so I won't be around too much again.
 

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Discussion Starter #12
Mike and Coppertop,

This is getting fun!

First I forgot to mention which side of the fuel gauge to use the potentiometer, but Coppertop touched on it. It should be the signal wire to ground. Also I know for a fact the Pros will actully use an actual fuel sending unit on the bench.

Second, to answer the resistance to temp question. The answer is, As the engine temp increases the resistance decreases.
I proved this by running the 12 v side of the temp gauge to a single "c" cell battery. Then ran the signal side of the gauge to the insulated side of an old temp sending unit. Then run a jumper wir from the "body" of the sending unit to the neg/ground side of the battery. You should also have a jumper wire from chassis of the gauge set also to the neg/ground side of the battery. This will move the gauge reading to "Cold". Now take the signal wire attached to the insulated side of the temp sending unit and touch it directly to the neg/ground side of the battery, the gauge will now move to "Hot". NOTE: only hold to neg/ground momentarily do not bury the gauge at the "H" side of the meter as this could damage the gauge. Just hold it ther long enough to see it move to the "Hot" position. This note should also be followed for the gas gauge test also.

Mike, in regard to the Tach, you can do the test I mentioned earlier by hooking the tach to any vehicle. Even an HEI car has a NEG coil terminal. So you don't have to test it on the particular vehicle that it will be installed in.

Coppertop, looking forward to testing out my Oil Press and Amp Gauges next. I'll let you know how it goes. I don't have any idea what the resistance range of an Oil Sending unit is but I'm sure I'll figure somethig out.

Also I want to do some further experimenting with the Temp Gauge by puting the Send Unit in boiling water with a baking thermometer. Once it gets to an aproximate temp maybe around 200 degrees then I can put it back into my test and hopefully get a mid gauge reading.

Have fun,

Fastss396man <BLOCKQUOTE>quote:</font><HR>Originally posted by Coppertop:
Hey guys,

I initially would have opted for you guys to send your stuff to the pros--but after reading your posts, it seems you just want to 'check them'. I have no problem with that, the only reason I suggest going to pros (and Brian, of course they won't let you in on there "secrets",--I don't reveal my restoration secrets on vintage radios since I was the one that worked on them so that is understandable) is they can virtually over-haul them.

For example guys, if you are not familiar with the tach's, the solder connections like to go on them causing intermitten/crazy/or no operation at the worst time. You can't just simply resolder them because the old materials actually "reject" solder--one must actually use little wires or jumpers and carefully reconstruct the circuits.

It's all about reliability--that's why I suggest pros.

BUT, I can respect just checking them.

You can check the gas guage as you mentioned, I always tell people to go to radio shack and get (2) 100 ohm resistors. (1) 100 ohm in series with the sending wire to ground will make the guage go past full, (2) 100 ohms in parallel will yeild 50 ohms, this in series with the sender connection on the gauge to ground will make it go to about 1/2. Ground the sender connection for EMPTY.

Temp gauage, same basic idea--but I do not know the proper ohmic range for a '69 temp gauge or whether or not the resistance increases or decreases with temp.

AMP guage does NOT register AMPS!!! in the factory guages. They are actually tiny voltmeters.

The amp guage recieves a voltage via the voltage drop found in the length of wire between the battery junction block and the horn relay. I don't know about the '69's, but for the '70-72's, about .5 volts across it will indicate 40 amps of draw thru the main 10 ga wire in the front of the vehicle that links battery power to the horn relay and all the other circuits.

Per Elree Colby:

Go to Radio Shack and get (3) equal value resistors around 500 ohms. Connect them in series to a 1.5 volt battery (C battery is fine). Connect the connections on the AMP gauage to the legs of the CENTER resistor--which will have approx. .5 volts across it. The guage should deflect to one side, reverse the leads to the back of the amp guage and it should deflect the other way, indicating a good guage.

Tach--my favorite!!

If your not set up for this forget it! Some people have gone to the trouble of getting a junk distributor, a power drill, and a battery! Spin the distributor shaft with the drill (you need to know the speed of the drill) and the Tach should inicate that speed if you EXACTLY REPRODUCED HOW IT IS CONNECTED IN THE CAR.

If you have test equipment like a signal generator, you can carefully hook it up to the tach and use that (I have not done this--another member had).

I'm actually building a circuit for bench top testing of tach's, but it is NOT ready yet.

Bottom line, if you are in doubt, send it to a pro!

Brian, Welcome to Team Chevelle!

P.S. guys, I'm only covering for John Muha while he's away on business so I won't be around too much again.
<HR></BLOCKQUOTE>



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69' SS396 Chevelle, L78 396/375hp, M-21 Close Ratio, 10 year Resto, It's brand new again!
 

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Discussion Starter #13
<BLOCKQUOTE>quote:</font><HR>Originally posted by fastss396man:
Mike and Coppertop,

This is getting fun!

First, I forgot to mention which side of the fuel gauge to use the potentiometer, but Coppertop touched on it. It should be the signal wire to ground. Also I know the Pros will use an actual fuel sending unit on the bench.

Second, to answer the resistance to temp question. The answer is, As the engine temp increases the resistance decreases.
I proved this by running the 12 v side of the temp gauge to the + positive side of a single "c" cell battery. Then ran the signal side of the gauge to the insulated side of an old temp sending unit. Then run a jumper wire from the "body" of the sending unit to the neg/ground side of the battery. You should also have a jumper wire from chassis of the gauge set to the neg/ground side of the battery. This will move the gauge reading to "Cold". Now take the signal wire attached to the insulated side of the temp sending unit and touch it directly to the neg/ground side of the battery, the gauge will now move to "Hot". NOTE: only hold to neg/ground momentarily DO NOT bury the gauge at the "H" side of the meter as this could damage the gauge. Just hold it there long enough to see it move to the "Hot" position. This note should also be followed for the gas gauge test and any other tests we may come up with.

Mike, in regard to the Tach, you can do the test I mentioned earlier by hooking the tach to any vehicle. Even an HEI car has a NEG coil terminal. So you don't have to test it on the particular vehicle that it will be installed in.

Mike and Coppertop, looking forward to testing out my Oil Press and Amp Gauges next. I'll let you know how it goes. I don't have any idea what the resistance range of an Oil Sending unit is but I'm sure I'll figure somethig out.

Also I want to do some further experimenting with the Temp Gauge by puting the Send Unit in boiling water (Mikes idea) with a baking thermometer. Once it gets to an aproximate temp maybe around 200 degrees then I can put it back into my test circuit and hopefully get a mid gauge reading.

Coppertop could you be a little more specific with the hook-up for the Amp Gauge test you mentioned.

Thanks

Have fun,

Fastss396man

<HR></BLOCKQUOTE>
 

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Discussion Starter #14
Still need help with the Oil Pressure Gauge.

I cannot get it to respond properly.

Any bench test avail?

Thanks.

FastSS396man

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69' SS396 Chevelle
L78 396/375hp
M-21 Close Ratio
10 year Resto
It's brand new again!
 

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Coppertop,

You mention sending gauges to the Pro’s. If I have to part with the cash, this may be worthwhile. Where are the Pro’s? Do you know who would specialize in 69 gauges? I’d like to see what the cost are, so I can decide if I’m going to test on my own and hope for the best, or send them out.

Thanks...
 

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Discussion Starter #16
Coppertop,

I will probably give "American Classic Restoration" a call, (508)278-0020 or contact at www.american-classic.com they have some general pricing at their web site.

Also contacted "The Tachman". E-Mailed him at his web site with a few question. Gary the Tachman asked me to give him a call on his toll free number so we could speak professionaly. When I gave him a call last Tue he was quit rude. I tried to ask a few basic questions to determin if I needed to send my gauges out. He gave me a bucket full of grief if you know what I mean. He said he didn't have time he was so busy. Did I realy need some thing fixed or was I just picking his brain. Then he gave me a lecture about the .13 cent per minuet the toll free line was costing him. I said I know for sure I need my clock repaired if I could get a price on it he said "Send it to the Clock Doc". I couldn't believe the way the conversation deteriorated so quickely.
I definitly know where I'm not sending my oil gauge!


This guy says he's owned 5 69's. Now I know why he's not a member of "The Team"!

Anyhow the "Clock Doc" has the best price for my clock repair $39.00 for basic service. Coils replaced for an aditional $15.00 or Quartz conversion for $89.95 plus add $8.00 for return shipping for any of the repairs.
The Clock Works
1745 Meta Lakes Rd.
Eagle River, WI 54521
PH 1-800-398-3040 www.clockwks.com

Quartz conversion in the long run sounds like a better value. However you lose the original "tic-tic" movement of the second hand. With the quartz movement the second hand will sweep.

American Classic says they will test for free, see their web site. I just hate sending my gauges across the country if there is nothing wrong with them. They were to hard to come by. Hate to have something go wrong in transit.

I'm pretty well convinced at this time that my oil press gauge is bad. When I perform the test sugested in Chilltons the gauge should deflect all the way to the "High" side of the gauge and it won't. I performed the same test with my good aftermarket gauge set and the test proves out good.

Looks like about $89.00 for the oil gauge repair at American Classic.


Going to test my Tach one more time. It seemed to be sticking but after blowing on it to clear out any dust and so forth it seems to be sweeping very nicely now.


Let me know what you find out and decide to do.

Brian
FastSS396man

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69' SS396 Chevelle
L78 396/375hp
M-21 Close Ratio
10 year Resto
It's brand new again!
 

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Brian,

You’ve done a lot of homework and saved me a lot of grief. American-classic is only a 2-hour drive for me. I’m busy with other projects right now, but I’m going to give them a call this week. I agree finding a factory gauge cluster is not easy and certainly not cheap. If things work out I’ll just drive my gauge cluster up. I like the Quartz conversion idea.

Thanks for all your help,

Mike
 

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Discussion Starter #18
Mike, I have another "heads-up". I spoke with Ken at American Classic Resto today, what a nice guy. Now that's how you do buisness!
The heads-up is on the quartz conversion for my clock. After talking to Ken I found out that if the Clock Doc does the conversion my set knob will be rendered useless, I would have to reach up behind the cluster any time I would need to reset the clock.
If American Classic does the conversion, the set knob will be incorporated into the conversion and be used to set the clock like it is suppose to.
American Classic is more expensive but sounds like it's worth it.
Also talked to Ken at Am Cl about converting my Amp Gauge to a Volt Meter. For $89.00 it's a done deal.
They do not change the appearance at all it will just read a little higher on the amp scale.
This will also save me alot of rewiring in the engine compartment. I won't have to change the forward light harness.
I can add in one Brown wire into my existing engine harness for the Tach.
And I will be able to use most of the existing wire I already have in place for my Auto gauges.


FastSS396man

------------------
69' SS396 Chevelle
L78 396/375hp
M-21 Close Ratio
10 year Resto
It's brand new again!
 

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Brian,

I also called American Classic Resto and thought they were great. I think I'm going to visit them in the next month or two and have them resto my cluster.

mike
 
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