Switching in voltmeter for ammeter

[Gunner]

I'm interested in switching the standard ammeter for a voltmeter in ERA 707. Has anyone done this in a late-number ERA? I know all the generalities about the change, I'm looking for very specific ERA/Smith gauges info if anyone has it.

If possible, I'd like to get the ammeter feed wires out of the power loop - leave them in place for a refitment, but eliminate the high power running all the way through them. What would I disconnect/cross connect around the alternator to do this?

Also, where's the best switched +12v and unswitched +12v points to tap under the dash?

Thanks!

[patrickt]

Bob created specific instructions for the switch out. Check this thread and his post half way down with the link to the exact ERA sheet.
Any tricks for swapping out the amp gauge to volts?

[Gunner]

Aces. I love this group - I've already found that the collective knowledge posted here over the years constitutes the bible of Cobra ownership...

[RICK LAKE]

Gunner If you are just changing to a volt meter, connect the 2 wires from the amp meter and tape them together. This is the easiest to do. All you have to do with the new gauge is tap into the wires you taped on one side, run a ground wire to one of the ground studs, and tap into the lighting for at night driving. If you drop the steering wheel, it makes this job real easy to do.
You where asking about 12v switching. Are you adding an accessory to the car? There are extra tangs for switched voltage. Here is the thing these switchs are not ment for alot of AMPS going though them It burns out the contacts. Hide and acc board under the dash with a main fuse of 100A's couple smaller fuses of the 10-20 limit. Run a #10 gauge wire (red) to the starter soleniod on the battery side. If any thing like a Fan or Amp for a radio is used, make sure they are running on a relay. There is a BIG differents between steady flow and on and off flow when a curcuit is turned on and off. A coolant fan may use 12-15 amps when running but spike 50-60 amps to get the thing to startup for a split second With the extra electrical I have added to #428, I have gone to a 120a charging system and a voltage meter. Good luck, unhook the battery and take your time, you will be fine. Rick L.

[Gunner]

Originally Posted by RICK LAKE

Gunner If you are just changing to a volt meter, connect the 2 wires from the amp meter and tape them together.

Thanks, Rick, I realize that's the easiest solution and even permits reverting to the ammeter easily. But it still leaves those two wires, carrying nearly all of the electrical system's juice, running through the car. I'd just as soon get them out of the circuit for safety and to make it easier to upgrade the electricals. For one thing, I expect to need to add HD cooling fans for my climate (the car was built and run in the Northeast, and California's central valley is HOT).

I know a lot of classic car owners and shade tree mechanics are terrified of the electrical system - they'll throw a wrench on an all-aluminum engine or suspension or whatever without a second thought, but get the shakes when they have to crimp a terminal. I've got a lot of experience with automotive electricals and have no problem doing anything that needs doing; my concern here is doing it right with respect to this car.

If I didn't hate ammeters so much, I wouldn't bother.

[RICK LAKE]

Gunner if you are not racing and have a splitter or the added small twin fans in the car, you shouldn't have any overheating problem. Bob at ERA has made sure that the raditor and fan with splitter or opitional fans would be more than needed to cool any 427 and up motor in an ERA cobra. If you build a schroud for your cooling fan this will help even more. I run the twin front fans because they look neat. The splitter works better than the fans at speed. Which radiator are you running, copper or aluminum? I started with copper and with racing went to aluminum. Thermostat is another issue with the motor running cool. 180f IMO and I use work about the best. Too much timing or running too lean will also raise the coolant temps of the motor. ERA doesn't recommend rapping headers with header wrap. I have the pipes coated and have them wrapped for 12 years, they are a little rusty but the temps where lowered 15f under the hood.
I think if you check with ERA you will find out if your car has the extra wiring for the second set of coolant fans.
I do agree with you about amp gauges being not the best gauge in the electricial system. Have to remember that in the old days and that ERA's replica car is very close or original cars electric system. I know that my amp gauge would pin when some thing turned on or the starter was engaged. Check for a 2 wire connection on the l/s of the under hood harness by the alt harness, you might be surprised and have them. Rick L.

[Gunner]

Rick, I don't even have the CAR right now. It's on a transporter headed west; I should have it by next weekend. It was so well spec'd by the original buyer and ERA that my list of things to change is real, real short.

It has the splitter and I believe it's an aluminum radiator. At most I expect to have to add the dual front fans, but I won't know until I drive the car next summer. I may be lucky - it's not a super-radical engine and it does have the splitter and extra venting. But all things being equal, 105-degree days will probably mean the booster fans.

Ammeters haven't been a useful gauge since generators went out. I don't know why they keep putting them in new cars. A voltmeter is a one-stop diagnostic for your whole electrical system - better, even, if you keep it powered all the time and let it stay active while cranking. I'm glad Smiths makes a truly old-school one - the one with colored bars doesn't look right at all. There's one that looks exactly like the ammeter.

[xracerbob]

I went with the voltmeter from the start and did something similar to what Rick suggested. I got a male/female covered spade connector and connected them and taped them to be sure nothing came loose. Trying to remove it completely would be quite a chore on a completed car. Once you see how nice the ERA wiring harness is done, I think you'll feel better about just connecting the two and leaving it.

[Gunner]

xracerbob: You're probably right.

Ouch, just found out the voltmeter is about $100 delivered. The other good thing about voltmeters is that they're inexpensive... :P

[PANAVIA]

The removal of the WELDING RODS that constitutes the ammeter wiring is a great leap forward in electrical safety in the car.

We encourage it in all vintage cars where a voltmeter is available. --

Steve