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Relay conversion for top operation & electric choke Q
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Author:  wjajr [ Wed Mar 26, 2008 6:12 am ]
Post subject:  Relay conversion for top operation & electric choke Q
76 Dart GT Convertible:
To lessen the load on the original top switch I have decided to instal a relay system.

What circuit would be best to tap into to operate the low power side of the relay, perhaps orange?

This car has an electric choke, that was not the case when she was built. Which ignition switched circuit would be best to feed the choke. I don't know the what the current draw is for this device, but I do know it is continuous when the car is running.
Author:  Sam Powell [ Wed Mar 26, 2008 6:45 am ]
Post subject: 
On my '69, I think the orange is the dash light circuit. I would come off the high side of the ballast resister to power the choke. If you want to raise and lower the top without the ignition switch on, then power your relay with the yellow, which is the dome lights, or red which is the cigarette lighter. These are '69 colors, but I suspect they are the same. Do you have afactory service manual, or at least a chiltons or Haynes manual?
Sam
Author:  RedFish [ Wed Mar 26, 2008 7:00 am ]
Post subject: 
The original switch and its power supply shouls connect to the signal side of the relay/s.
The choke power at switch on will be routed through the same components or fault points as everything else beyond the fusable link so may as well connect it to such as blue at altenater.
Author:  SlantSixDan [ Wed Mar 26, 2008 7:24 am ]
Post subject: 
Good idea to put in a relay. Use a good-quality SPST (normally open) relay from the likes of Bosch/Tyco or Potter & Brumsfeld. The relay will have four terminals, numbered 30, 85, 86, and 87.

30 is your power feed. Connect it via an appropriate fuse to a source of +12v. It would be easiest, I think, to use the ammeter input stud as your power takeoff; the top motor/pump is a high-current device. Place your fuse as close as possible to the power takeoff.

85 and 86 are the relay's trigger terminals. #86 is positive, and #85 is negative/ground. When you apply +12v to #86 and ground #85, the relay will close (complete the circuit). So, #86 gets the wire from the original top switch, that originally went directly to the motor/pump. #85 goes to ground.

87 is your power output. Connect the wire to the pump/motor here.

The choke can be connected to the input side of the ballast resistor. That's the one that gets +12v when you turn the ignition switch "on". You do have a thermal modulator on this electric choke, right?

(I bet your Dart GT is a '67, rather than a '76. ;-) )
Author:  wjajr [ Wed Mar 26, 2008 8:00 am ]
Post subject: 
Dyslexic dept:

76-67 what's the difference?

Thanks, I understand how the relay is wired, just wanted to check on orange (dash lights) curcuit being a good switched feed for the low current side.

Presently the switch is protected by a 30 amp circuit breaker, and powered directly from the amp gage. There won't be much to do to rewire this puppy.
Author:  wjajr [ Wed Mar 26, 2008 8:18 am ]
Post subject: 
Hummm, thermal modulator...

I'm not sure what kind of a device a thermal modulator is, looks like, or where one would fid it.

This is a Holley 4160, and the install & adjustment instructions (found on line) recommend fusing the choke at 10 amps. What I have looks like the carb in the instructions.

I will feed from the 12 v side of the ignition ballast as advised, and pop in a 10 amp inline fuse.
Author:  SlantSixDan [ Wed Mar 26, 2008 8:52 am ]
Post subject: 
Quote:
76-67 what's the difference?
Nine. :mrgreen:
Quote:
Thanks, I understand how the relay is wired, just wanted to check on orange (dash lights) curcuit being a good switched feed for the low current side.
Not sure how you envision using the orange (dash lights) circuit here. The low-current side of the equation is taken from the car's original top switch circuit. I don't have a wiring diagram in front of me, though, so it could be a little more complex — if the top switch sends power of one polarity to raise and opposite polarity to lower, you may need to use two relays.

The choke modulator is a device that senses the engine's temperature and modulates power to the choke heater. If there's no such modulator in series with the choke heater, the choke heater comes on whenever its circuit is live, which works OK but not great — it means constant current draw you don't need to be supplying, and it means the choke plate follows a set opening-over-time curve that does not account for the engine's needs...and if the engine doesn't happen to start immediately (either because something's the matter or because you wait between turning the ignition on and cranking the engine) then the choke begins to slack off before the engine starts.

I'm not sure if there's some kind of ambient temp sensor or other thermo-time switch built into the Holley electric choke housing, but my vague recollection is that there is none. If you look at the Electric choke kits post, you can see the thermo modulator in the picture. It's the potted black box about 1" by 1½" with a copper mounting tab and a wire lead. It gets mounted somewhere near the head/manifold (one of the engine lifting boss bolts is a good pick on a slant) and modulates the choke heater circuit ground resistance in response to sensed temperature.
Author:  wjajr [ Wed Mar 26, 2008 9:44 am ]
Post subject: 
There is no provision for a heat modulator that I can see:
http://www.holley.com/data/Products/Tec ... 8108-2.pdf
page 3. Perhaps it is internal as the instructions say to feed it with 12v's.


As for the top motor wiring, there are presently no relays used. The switch is feed from the amp gage post, and direct to the motor using two conductors, one for up & one for down.

I'm going to use two relays one for up & one for down using the existing dash toggle switch to operate the low amp side of the relays from an ignition switch feed.

Looking at the wire diagram I just feed it from the fused side of the radio circuit.
Author:  RedFish [ Wed Mar 26, 2008 3:23 pm ]
Post subject: 
Point to ponder...
Polarity is reversed in the switch and either wire will become the ground side of the circuit. Basiclly the same or more current passing thruogh the OEM switch after relays are added.
Author:  SlantSixDan [ Wed Mar 26, 2008 4:16 pm ]
Post subject: 
Quote:
Basiclly the same or more current passing thruogh the OEM switch after relays are added.
How do you figure? The relay handles the high current drawn by the top pump/motor; the switch just triggers the relays.
Author:  RedFish [ Wed Mar 26, 2008 5:06 pm ]
Post subject: 
The switch in question is a 3 position switch. The pump motor doesn't have 2 windings. it runs 2 directions on 2 wires. The switch contacts control polarity. May be just a more complex type relay/s and additional wiring required to get the factory switch isolated from motor current.
I'm thinking out loud again.(sorry) I'd have to see the schematics.
Author:  Joshie225 [ Wed Mar 26, 2008 5:32 pm ]
Post subject: 
It's a 3-position switch, but it's center off. Up provides +12V from a 30 amp circuit breaker to the Up wire/terminal of the pump motor and down provides power to the down terminal of the motor just was wjajr described. The 3rd wire from the motor is ground. This comes straight from my reprinted FSM.

RedFish,

Please have a firm basis for any advice you provide. If you don't know an answer you are best off not posting.
Author:  wjajr [ Wed Mar 26, 2008 6:05 pm ]
Post subject: 
The switch that presently operates the top is a three position intermittent toggle. When it is centered nothing is energized, push it up to rase the lid and a full thirty amps flow down a # 12 wire yellow to the pump. release the switch and it returns to off, push it down and the lid goes down with 30 amps flowing down a brown #12 wire.

What I am going to do is replace the up contact with relay "A" yellow, and the down contact with relay "B" brown.

I will utilize the old existing toggle switch proudly mounted on the dash adjacent to the headlight switch to activate each relay as needed to either rase or lower the top. Anyone operating i the top will never know relays are doing the heavy lifting in place of having the 41 year old switch carry 30 amps. By doing this I will reduce the current draw through the old switch by huge amount, and won't need any fire permits for out side burning before lowering the top.

All that is simple. My concern was which circuit to tap into to feed the low draw side of this set up that was only energized when the ignition is on. I have decided that the same circuit the radio is feed from will do just fine where there is little draw, and not constant, rather a very low duty cycle.
Author:  RedFish [ Thu Mar 27, 2008 4:41 am ]
Post subject:  I dont like to argue
In your plan discription you have current flowing down wires like water. It wont flood the truck friend. Current travels in a circle. Same current will flow upstream on the oposite wire seeking a ground. That ground is in the switch. Relays that will ground the line out wire when open would work.
Author:  Charrlie_S [ Thu Mar 27, 2008 5:54 am ]
Post subject:  Re: I dont like to argue
Quote:
In your plan discription you have current flowing down wires like water. It wont flood the truck friend. Current travels in a circle. Same current will flow upstream on the oposite wire seeking a ground. That ground is in the switch. Relays that will ground the line out wire when open would work.
The switch does NOT provide a ground path. The switch only has three wires, 12v feed, up, and down. The ground path is the third wire on the motor, which is a "body" ground connection.
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