Electrical genius needed

[jbearden]

And I fat fingered the the keys on the title.Didn't catch it til I hit enter.GENIUS****


How can I keep my factory gauges working in my 66 Charger with a 5.7 hemi and 545 trans and keep everything in one piece while running a Hotwire harness?I don't want to burn up my EL or any gauges because it's a brand new instrument cluster, plus I just spent countless hours making an under dash and engine compartment harness.

 

[747mopar]

Your probably going to need to be more specific about everything but I wouldn't see why you couldn't install the factory oil pressure and water temp sending units in the 5.7 to get those working. I'm assuming the trans doesn't have a place for a cable driven speedo but there are boxes out there that convert the signal for these kind of conversions to make your original speedo work.

 

[dpstark2]

I don't know the new Hemi, but I know the first gen Charger wiring quite well. If there are ports on the motor that can be used with the stock sending units, you can easily make the oil and temperature gauges work. Just use the stock sending units on the new motor and retain/remake the original wiring from the cluster through the bulkhead to the sending units. I don't know what you're doing for a fuel tank, but if you can get a stock type sender in it or a Mopar-type sending unit (10-90 ohm, full-empty), the gas gauge will still work. For your speedo, you'll need to see if there is a mechanical speedo adapter for your trnas. I really don't know anything about that. You'll probably need to bypass the ammeter. There are ways to make it "do stuff" and move around, but it's kind of pointless with your new engine and alternator.

To power everything: You will need a switched 12V source going to the voltage limiter in the gauge cluster. Whether you're using the original style limiter or a new solid state one, you just need to tap switched 12V and feed the limiter, then run its output to one side of each of the temp, oil, and gas gauges. The other side of each gauge goes to the sending unit. Which side you use doesn't matter. You can reuse your original wiring here, or remake it.

Your dash light output from the headlight switch, which comes off the dimmer, goes to the AC power pack under the dash (orange wire). The output of the power pack (white wire) goes to the EL dash and anything else EL you have. I'm pretty sure they have a specific smaller connector that doesn't work with anything else.

Your tachometer will have an external sending unit. It also, I believe, takes 12V switched that you'll need to hook up. I do not know how to make this work with your new Hemi, but if you swap out the sending unit guts for a solid state one, you can probably feed it from the computer's tachometer output, and run the sending unit output to your stock tach. If you have a '67 tach, it is different and has an internal sending unit.

That's about it (ignoring all the holes in my post). 12V switched to tach sending unit and voltage limiter. Dimmer output to power pack. Power pack output to gauge cluster. Hook up original sending units. Wire voltage limiter to gauges. Mechanical speedo conversion. Hook up fuel sending unit. Bypass ammeter.

Good luck. More details would be helpful.

 

[Icecobra]

Fuel gauge is easy,
Temperature add the stock sending unit to the new motor
Oil pressure use the stock sending unit to the new motor
Change the amp gauge to a voltage meter this will require a bit more wiring but is easily do able
Tach use the white wire on the computer control and tap in to it and it will work
Speedometer is going to be the hardest its input to the gauge is completely different than the new trans output your going to have to find a conversion unit they do exist. Probably going to have to do some type of electronic to mechanical system...
The hot wire system is pretty straight forward your going to need to put a bulb for check engine light somewhere if you want that.

 

[jbearden]

Thank you guys.I figured that The water temp, oil, fuel and speedo would be pretty simple but I was really worried about the tach and new alt.I have done some reading about the tach and with the use of an MSD tach signal and a Dakota Digital signal interface it can work.It does somewhat confuse me still because there is only one wire going to the tach on the factory harness and I am unsure what will need to be rigged to make it work.
The fuel tank will be my stock tank with the sending unit(maybe used as a return line?).It will have a tank mounted
Aeromotive pump with a Corvette filter/regulator/return mounted in front of it.
Oil and temp should be simple enough and the speedo will more than likely use an electronic to cable converter.The alt has me really worried.After all the money and time spent on building this harness and a brand new set of gauges, I would be sick if I fried them.As for the check engine light, I was contemplating using my cars existing parking brake light for it.
Thank you guys.I will take plenty of pics during the swap with as good of a write up as I can give.This swap will take place next month so hopefully everything will be figured out by then.

 

[dpstark2]

In '66, the tach had a remote sending unit. It took the flyback off the coil and converted it to a DC voltage that fed the tachometer- this is the one wire you're referring to. The sending unit is a hockey puck shaped metal can under the glove box. There is a solid state replacement made for it that would allow you to directly use any 1-pulse-per-ignition event output like your computer probably has and still drive your tach correctly.

I'm unaware of anyone that has converted a '66-67 Charger ammeter to a voltmeter, but that would be awesome. You will not be able to have a fully functioning ammeter because your alternator puts out way too much current to feed it all through the ammeter. If you have wired up your car that way, change it before you install the engine. You will fry your ammeter. If not, all you can really do is feed the factory accessories off the negative side of the ammeter and wire the constant hot line to the feed side. This way, your ammeter will show discharge all the time and show any loads you are activating. I repeat: Do not wire your new hemi's alternator charge wire through the ammeter. You will fry it.

Also, you can only feed the factory accessories this way- not your computer, a stereo, etc. That will pull too much current through the ammeter and also fry it. Overall it is safest to bypass and ignore the ammeter. Sorry- it's just the way it is. It'll still light up and be pretty!

 

[gibber]

As we discussed, as the builder of your new gauge cluster, the ammeter issue needs to be addressed. Bypassing it would be my recommendation as well. Wish I could come up with an ammeter to voltmeter conversion for the first generation Chargers, but it is right now beyond the scope of this hobby business. I know someone on the 66-67Charger.com website had done some work on this conversion if you want to look thru the archives.

Mark
www.thegaugedoc.com

 

[66383charger]

Hi There,
This is a link to my voltmeter conversion. PM me if you need any more info.
Jeff

http://www.forbbodiesonly.com/moparforum/showthread.php?66671-Custom-volt-meter-conversion

 

[jbearden]

I did talk to Redline today and they turned me down because they refuse to touch anything 1st gen.Wanted to sell me a whole new set of gauges instead.While it is tempting to go with what they offer I would rather keep the EL.
66383Charger, I would be very interested to know more about what you have done so that the best of both worlds is possible.I will send a PM with my email info.Right now I am really starting to think that it would be best to use another car I have for the 5.7 Hemi swap.

 

[66383charger]

Send me the 5.7 and I will send you a first gen voltmeter conversion...lol
Check your email!!

Jeff

- - - Updated - - -

Link and more photos at the other site hang out at.

http://www.66-67charger.com/forum/ubbthreads.php?ubb=showflat&Number=147076&page=1
Jeff