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General Discussions => The Lab => Topic started by: SSLtech on October 11, 2004, 11:38:29 AM

Title: Wiring up a Cobra
Post by: SSLtech on October 11, 2004, 11:38:29 AM
A friend has asked me to wire up a kit car from the ground up. All new components, all new wire, not a purchased harness.

I'm thinking of everything that I'd have to wire to: The car will have no air conditioning (as far as I know!) so here's an attempt to list everything that I can think of.

'Hot' with Ignition in ?Run? condition:
Windshield washer motor
Windshield wipers
Headlights
Sidelights
Taillights
Dash illumination
Dash Indicators (lights, main beam, Battery)
Side markers
License plate lights
Ventilation fan
Direction turn signals
Reversing lights
Starter Switch
Starter/Solenoid
Ventilation Fan
Ignition/engine components (coil, auto choke heater, etc.)
Stereo enable line

Permanently Fed 'Hot'[/b]:
Radiator Fan
Dome Light/Door Pin Switches
Brake lights
3rd Brake light
Hazard lights
Stereo main power/'keep-alive'

-He wants a "start" button on the dash instead of on the ignition key, I'm thinking that it might be wise to put an "Engine running" sense in there to lock out reactivation the button until the engine stops again... anyone got any bright ideas about how to do it simple using a circuit running on 12V?

The engine will be presumed to be a new Ford crate motor (466 cu. inch)with an alternator... Carburettor-fed- not sure about sensing "engine running" from either the ignition trigger (I haven't much of a clue how it's done on modern Ford engines!) or the alternator field coil, I suppose...?

Anyone got any ideas? -PRR? Any great ideas you'd like to see incorporated?

Keith
Title: Wiring up a Cobra
Post by: VacuumVoodoo on October 11, 2004, 12:31:59 PM
How abour a simple nifty antitheft device ?

I made one a few years ago, takes 1 relay and 1 diode. The way it works is that the relay is normally open and cuts power to the ignition coil. You have to activate some other electrical part to latch the relay via the diode. In my case you had to have rightturn indicator on to start the engine.
Title: Wiring up a Cobra
Post by: Gus on October 11, 2004, 12:35:40 PM
One idea is a voltage comparator than switches out the start button when the battery voltage is >13.somethingVDC.  A car not running should have a battery voltage of under 13.00VDC IIRC

Sitting lead acid about 2.0VDC

charging lead acid 2.2DC

topping off in the 13s

Please check the above voltages I am going from memory.

Engine vacuum with a presssure transducer or mecanical switch
Title: Wiring up a Cobra
Post by: SSLtech on October 11, 2004, 01:03:15 PM
Antitheft was something that I was thinking about. -Back in the UK I wired up a beetle (with generator, not alternator) and wired a cut off with a kill to the coil feed, but also a secondary short across the points... that way if anyone tried to hot-wire past the kill switch by clipping straight to the coil, they'd still have no fire...

I'll start looking for a new general purpose fuse panel. I think I'd like to use the modern blade type fuses... If I get one with the hot sides already banked together, I might take a look at it... The guy who wants the project done is adamant that there be NO junkyard part used if at all possible...

I think Skycraft had some NOS motor boat fuse panels for sale... I'll take a look!

Keith
Title: Wiring up a Cobra
Post by: SSLtech on October 11, 2004, 01:32:35 PM
Anyone got a simple logic circuit for that wierd "brake-light-used-as-turn-signal" setup? I don;t know if this car will have seperate turn bulbs at the rear or not... or if it's a red/amber cluster or a single red bulb...

The logic for that always made me wonder... how do they do it in American Cars?-It's not legal anywhere else I don;t think... certainly completely illegal in Europe, and darn it, it's confusing over here if anyone modulates the brake pedal while signalling a turn... Specially if the vehicle has no third brake light...

All the same, if it has to be done for this car, I wonder how it's traditionally done. -In the '60's, did they use transistor logic, or relays? -I always wondered!

Keith
Title: Wiring up a Cobra
Post by: PRR on October 11, 2004, 01:36:55 PM
> not a purchased harness.

That is insanity. Even by audio-tech standards. You will be very sorry.

If you can't buy a harness, there are outfits that will make you a semi-custom. Pay what it costs: it's worth it. Anyway I don't think you can buy all the switches and connectors one-by-one for the price of these kits.

http://www.painlesswiring.com/
http://www.hotrodwires.com/
http://www.ezwiring.com/
http://www.centechwire.com/catalog/rods/rodharness.html
http://www.hotrodders.com/t10988.html

As for starter lock-out: we never do this on key-start, why do it for button-start? Hitting the starter while the engine is running is not fatal, doesn't even do much harm. I did it all the time when the T-Bird's muffler worked and I was not always sure if the engine was running. I retired it (230K miles) on the original starter.

The usual way to sense if engine is running is to check the oil pressure idiot light sensor. If you run a gauge, put a Tee on the oil port before you drop the block between the fenders.

BTW: I think the electric choke should be wired from the oil switch. If the engine starts, stalls, and ignition is left on, you don't want the choke to hot-up. Ah, wait: they wire it from an extra terminal on the alternator: one that is only live when the alt is spinning, to avoid false-heat and also so it won't drain the batter in a start-stall event. Check the factory diagram for a similar model, or ask the choke company. Anyway you don't need a choke in your mild clime. Stomp the pedal 2-4 times, keep yout foot on the pedal, it will start and keep running long enough to get warm.
Title: Wiring up a Cobra
Post by: PRR on October 11, 2004, 01:45:42 PM
> that wierd "brake-light-used-as-turn-signal" setup?

What's strange about that?

Battery, brake-switch, to turn signal switch. When centered, brake feeds to both rear lights. When turning, the brake feed to that side is broken and switched to the flasher unit feed.

Unless you are restoring a pre-1980 car *exactly*, I do agree that you want amber turn and a 3rd-eye brakelight. I know my T-Burd always confused tailgaters because it didn't have the 3rd light.
Title: Wiring up a Cobra
Post by: PRR on October 11, 2004, 01:51:56 PM
> 'Hot' with Ignition in ?Run? condition:

You need an AUX feed. You should be able to run the radio or wipers with ignition off.

Headlights, taillights, and some other things must NOT be fed from the switch.

BTW: headlights have a rather special circuit breaker, not a fuse. It is self-resetting, so it always tries to give you light in an emergency, without starting a fire.

Ford gauges (different from GM) need a voltage regulator.

If you run non-electronic ignition on a 12V system, you must have a resistor in the coil feed, usually switched-out for starting (this bypass is not essential on all engines, but may be critical on a monster-mill).

That's another reason to buy the kit. They have checklists of all the things you haven't thought about, and how they are normally done.
Title: Wiring up a Cobra
Post by: PRR on October 11, 2004, 02:04:14 PM
> Any great ideas you'd like to see incorporated?

LED tail-lights

You have enough problems running a 466 in public without cops pulling you over for a dead tail light. Note how fast 18-wheel truckers are going to LED lamps in all required locations: they are expensive, but much cheaper than a citation.
Title: Wiring up a Cobra
Post by: SSLtech on October 11, 2004, 02:21:38 PM
Excellent input!

Of course, the turn-signal thing is easy once yo know how it's done....-I was thinking there was a box of relays with logic if/and/or/not feeding it... There I go, overthinking it yet again! :roll:

That settles it, I like the starter harness idea a lot! -Looks like you bolt in the fusebox and just string it out from there... looks a lot easier than when I wired up that Beetle... (which really was from scratch.. only thing that was original was the fusebox)

Of course there's always something else you think of later... like a horn for example...  :oops:

I'll ask about LED turn/brake signals... he might have a religeous objection, but I've even considered putting them on my own car for the exact reasons that you mentioned! (I'd have to come up with a mod to stop the flash rate from skyrocketing, you know the "you've got a bulb out" indication...)

Yes, there will of course be an additional switch position to drive the radio etc... Interestingly, the recent VW stereos will run for an hour without the key in the ignition, then turn itself off in case you've wandered off and forgotten that you left the radio playing... a nice feature, but yes you're correct, it actually "arms" from the "aux" and not the "run" position of course.

The chap in question actually has an original Shelby Cobra at the moment, but will be getting rid of it, for something that he can "play about with" in terms of mods and hopping-up... It'll be interesting how much he wants to keep as original (probably most of the outside stuff, for appearances sake) and how much he'll allow from the 21st Century... LED taillights are an interesting proposition... he might even want a slight "slug" on the turn on/off, so it's not quite as sudden...

Great thoughts!!!

Keith
Title: Wiring up a Cobra
Post by: PRR on October 11, 2004, 02:59:50 PM
> the "aux" and not the "run" position of course.

Apologies. Car electricians call this the "ACC" (accessories) position, not what I wrote.

If you are correct, that 1960s UK cars did not use the shared brake/turn lamp, then there is an AC Ace tail-lamp assembly with amber insert that will drop-on a 289 Cobra (and probably the 427). The Cobra maker will know what options are suitable.

> thinking there was a box of relays with logic

That would be the Rube Goldberg contraption in 1967-68 Cougars, to do the sequential-turn with brake on the same bulbs. This was so problematic that they transistorized it for 1969.

> stop the flash rate from skyrocketing

20Ω 10W resistor in place of each missing bulb. Or get the flasher from the place that sells LED tail lamps.
Title: Wiring up a Cobra
Post by: MikoKensington on October 11, 2004, 03:30:30 PM
Might I suggest wiring for neon.  Cars with neon illuminated undercarriages are sooo classy.   :wink:

Don't forget the 4ga. wiring for the 2000 Watt sub setup.  

Oh!  And the wiring for the LED equipped washer nozzles.
Title: Wiring up a Cobra
Post by: wilebee on October 11, 2004, 03:56:25 PM
Just a thought  are you going to have your friend sign off on all liabilities ?
you just don't want that cobra comming back to Bite ya.

Wil

Wilebee
Title: Wiring up a Cobra
Post by: BYacey on October 11, 2004, 04:22:50 PM
I am not sure if I agree with using a stock Ford Harness. I was involved in troubleshooting wiring in an early '70s mustang which had numerous wierd problems. Park lights would come on when the interior lights were switched on, and the interior light would dimly flash when a turn signal was activated. After tracing out the grounds in this vehicle (why the hell would anyone ever run a ground through the harness instaed of using the chassis? And why would the interior light and rear tailights share any kind of common ground wire within the harness?)  I came to the conclusion that Fords had the most stupidly designed electrical systems out of the 3 north american manufacturers.

If it was me taking on a project like this, I would obtain the stock connectors and make my own harness based on common sense. There are tools available to remove the blades or lugs from the plastic connector housings.
Title: Wiring up a Cobra
Post by: PRR on October 11, 2004, 04:44:15 PM
> I am not sure if I agree with using a stock Ford Harness.

I am assuming he means a Real Cobra, which is a UK AC Ace with a Dearborn engine. Essentially no Ford wiring involved, especially in the clone he seems to be involved in. (If it is a Real Cobra, there may be a lot of Lucas in it....)

> I was involved in troubleshooting wiring in an early '70s mustang

You seem to have hit an especially bad example. (Yes, there were a lot of bad days in Dearborn; but also in Flint and Stirling Heights.) All the 67-68s I worked on would play the radio without a key if you stood on the brake and pressed the 4-way-flash halfway, but your other problems are new to me. Aside from connectors, I've had little electrical problems on vintage Fords. Yes, the connectors got so bad that in the mid-1970s they radically upgraded them and advertized that fact.
Title: Wiring up a Cobra
Post by: SSLtech on October 12, 2004, 09:21:42 AM
Yes, the original is an Ace that Mr. Shelby so kindly shoehorned some muscle into... This is a "take two" so that some different things can be tried, without the feeling of violating or desecrating a piece of history. (sorta like adding a solid-state, balanced sidechain insert to one of the few surviving LA-1's out there... build a clone and modify that if you like, but don't desecrate the original!!!)

Glass-Fibre body (GRP/Fiberglass) means that you either runindividual grounds or start bolting to the tube chassis... Stainless tube chassis in this case...

Keith
Title: Wiring up a Cobra
Post by: jrmintz on October 12, 2004, 10:00:51 AM
Hey Keef,

What about a DVD player for the kiddies?  :green:

 :thumb:
Title: Wiring up a Cobra
Post by: peter purpose on October 12, 2004, 10:12:43 AM
Keef,
Don't forget the wiring for the trailer hitch..!!

pooter
Title: Wiring up a Cobra
Post by: PRR on October 12, 2004, 03:57:23 PM
> Glass-Fibre body (GRP/Fiberglass) means that you either run individual grounds or start bolting to the tube chassis... Stainless tube chassis in this case...

Standard hot-rod construction. Look in the Accessories pages: most of these kits have an optional ground bus and wiring for plastic cars.
Title: Wiring up a Cobra
Post by: SSLtech on October 12, 2004, 09:11:59 PM
I went round this evening and for reference took a few pics of the Shelby Cobra that he has... Boy it makes a lively racket! -It's been modded up a little under the hood, and the instruments aren't original, but it's a mighty noise when it's fired up, make no mistake!

And that footwell...  :shock:  -it's so far left that youalmost have to sqinch in at an angle, with your knees a little to the left of the steering column... (I'm 6-foot-two) but it's a grin-maker, that's for sure!

It looks simple. there's no dome light, no door switches, nothing like that to worry about. For the time being no stereo either (though I might provide some pre-wiring to the trunk) The battery lives in the back (that was news to me; I'd assumed it lived under the hood, but looking at the size of the motor, and making good and sure that the front remains clear for cooling, there's no easy-access place under the hood, so in the trunk it is!)

This is going to be a lot of fun. -Realistically I'd say give the project a year or so to be finished. I'll post a couple of pics tomorrow!

Keith
Title: Wiring up a Cobra
Post by: PRR on October 13, 2004, 12:14:04 AM
> that footwell...  -it's so far left ....The battery lives in the back

Which is this, the original or the kit-car? I don't recall where the batt was on a 289, though I would have thought above the passenger's feet. With the FE-427 block and rock-grinder tranny where the BMW/Bristol Six used to be, I'm sure there is no room for silly frills like feet or batteries.

What's this clone? I assume it copies the 427, not the 289: nobody seems to want to spend that kind of bucks for another Sunbeam Tiger, they all want POWER and Fender Bulges.

What engine? The 1960s FE boatanchor (best known as 390 and 427 T-Bird mills) or the 1968-1975 cant-valve big-block (made in 429 and 460 sizes)? The FE is authentic (only if side-oiler), but the cant-valve is a lot more practical, being a hair lighter and being in production more recently (while it was dropped from Burds and Lincolns soon after the gas-crisis of '73, it survived as a tow-truck engine until very recently). And also more ultimate power than any FE except the SOHC (and you think an FE or 460 looks big in there, try the SOHC). Though I doubt the 460 needs more than light massaging to totally over-power that chassis to 120MPH.

> It looks simple. there's no dome light, no door switches, nothing like that to worry about. For the time being no stereo either (though I might provide some pre-wiring to the trunk)

Buy a fusebox with several more circuits than you think you need. No dome-light because no dome, but you might want light in the footwell (or under the hood). Radio, if only for traffic-reports so you don't end up with 500 horsepower doing 2.5MPH around the jack-knifed truck. Run wires for the A/C, both fan and clutch: it may seem silly, but this IS Florida (or he might move to, ugh, Texas). You obviously want a radar detector power tap ("just in case"), maybe GPS too. And there is a nifty gizmo you clip on the visor and it reads all your Gee-forces, power and traction. You may have electric fuel pump, you may someday have fuel injection (Holley has a sweet carb-replacement FI unit almost big enough). So unless this owner is very no-frills and sure to keep the car "forever" (i.e. resale value is a non-issue), run lotsa wires. Difference in price for 12-circuit and 18-circuit is small. Difference if someone taps too much crap on one wire and sets the body on fire is large.
Title: Wiring up a Cobra
Post by: SSLtech on October 15, 2004, 12:26:36 PM
A picture for your delectation...

http://img.photobucket.com/albums/v379/SSLtech/Picture029.jpg

I'm actually getting the bug for this... I might actually try and build one myself...