I've been accumulating the hard parts necessary to convert my '65 idiot light Elky to factory gauges. Looking at the factory wiring diagram it appears I have to:

Ammeter

Add a Black & Blk/Wh 18ga. from the cluster, through the bulkhead, to the horn relay area
Install the ammeter shunt near the horn relay
Change connections to the horn relay to include ammeter shunt
Temp

Lift/bypass the Dk Grn wire connection to the Ign. switch
Swap sending unit to a guage type.
Oil Press

Simple plumbing
My questions are:

Are there terminals inside the unused "holes" in the bulkhead connector? (I haven't looked yet)
If not, are they available "one'sy two'sy"?
Which firewall dimple does the copper tubing use/go through for the Oil Pressure feed?

64 was the only year the shunt was used. Starting in 65 amp gauge wiring connections are to the horn relay (or close to it) and J-block. How you wire your cluster depends on which cluster you have. The 64 AMP gauge is not the same as a 65. See attached pic, lefthand gauge is 64.

You may have trouble finding the twin-lock terminals used in pre 68 bulkhead connectors.

http://www.chevelles.com/showroom/data/500/64_65ampgauge.jpg

The crimp terminals are called "GM (Delphi) Fuseblock Twin Lock". Sources are wiringproducts.com, part number 1122H, keeferperformance.com, part number 2973915, and jttproducts.com, part number 1122H.

There is a guage conversion kit sold by the popular vendors. It is priced about $250. It is USA made, but very poor quality. I bought one and returned it after one look. Had my gauges restored by Redline.

The oil gauge tubing goes through the hole about an inch below the end of the wiring trough, driver's side. It routes from the engine to the right side of the trough, through the trough, and U-turns into the firewall hole.

John... I forgot to mention that I had my ammeter converted to a volt meter. The needle is mid-range at 12.5 volts. The voltage is picked off the gauge cluster (no need to run a wire through the firewall).

Another tip: replace the black tape that covers the slots between the individual guage backplates (the clover leaf). That tape blocks the reflections from the light bulbs.

I wasn't aware of the change in guages between model years... thanks for the heads-up :thumbsup:

I have the "65 style" ammeter. I was wondering why it had such serious looking windings inside the mechanism... now I know why. This is the diagram I was referencing my work from:
http://i275.photobucket.com/albums/jj319/celba/stuff/WiringCrop.jpg

If the shunt is not used, how does the wiring change? Could you shed some light on this...

The two wires for the amp gauge terminate at the horn relay, black/white, and the J-block, black. The length of red 12 gauge wire, that connects to the same two locations, takes the place of the shunt resistor used on the 64.

Just so I understand correctly:

The ammeter is connected in parallel across the +12/10ga "battery" wire, and the Main output feed from the alternator ("seeing" the difference in potential between the two?)

That's correct, the gauge measures the voltage drop across the main power feed wire.

I'm still missing something here....

Being an original "Light" car, I don't have a J-block near the horn relay. The 10ga. reds from the battery, alternator (siamesed with an 18ga. to the regulator), and bulkhead all land onto one or the other of the two horn relay terminals - essentially the horn relay is one big J-block for the 3 wires. There's no way for the ammeter wires to sense a difference in potential....

Could someone sketch out a simple diagram of how this circuit is supposed to be landed on a '65 gauge car?

John

Not sure why your 56 doesn't have a J-block. The attached pic is from my 65 service manual. As you can see is shows one. If it was me I would add a J-Block. I believe the gauge will work if you were to use a 64 shunt resistor.

If you car has a junction block it will be located by the battery..

http://www.chevelles.com/showroom/data/500/P3230025.jpg

My mistake... I do have the J-block over by the battery. I was under the impression of needing one near the horn relay. So to clarify:

The bk/wh breaks out of the harness & terminates at the horn relay.
The blk continues across the rad support and lands at the J-block.

"The bk/wh breaks out of the harness & terminates at the horn relay.
The blk continues across the rad support and lands at the J-block."


That's correct.

Somthing I failed to mention. While 65 and 66 didn't use fusible links on the amp gauge wires, starting in 67 they were added. It's a good idea to install them at the horn relay and J-block.

Finished the install last night. Thank You Elree!! The terminals worked perfectly, and all the gauges are alive and moving.

I love this place!