Need help selecting relay/design

[Sleeperbee]

Hello resto folks. I've added some components to my 1969 Coronet that aren't original such as Holly Street Avenger carb with electric choke and Delta PAG electric fan. The controller and electric choke need 12 volt juice only when the ignition is on. My fuse box is stock and pretty booked up. I want to run a wire from one remaining accessory blade in the fuse box to a relay that will handle two connections (fan controller and ele choke) - like the relay for the stock two horn wires? Can someone recommend a specific relay item? Its my last item on this build!!! and I can't get over the hump. Thanks

 

[70chall440]

I would not pull the power from the accessory pin in the box, I'd pull it from the battery directly (with a fuse). You can then activate the relay via a switch using the accessory pin or somewhere else (lighter connection, etc)

Pretty much any type of relay will work, if you want to do it cheaply you can get some relays from your local parts store.

If you want a really good relay system, check this out.

MSD 75643 Stand Alone Solid State Relay- Black

 

[1 Wild R/T]

Since both items you want to power are located under the hood and the alternator/battery are under the hood it makes zero sense to try to tie them to the fuse box... Not to mention the fuse box will never live if your trying to power a fan off of it.. To many amps...

After looking at Delta Pag it looks like the kit comes with a relay... And a temp sensor/switch...

Place the relay in the area of the passenger front corner of the engine compartment, feed the main power from the output stud on the alternator, trigger the relay with a jumper off the blue voltage regulator feed wire... Ground the relay with the temp sensor....

 

[gkent]

That's a VERY expensive relay system and a waste if you only need one or two relays. Holley/MSD offer these at a much lower cost and available in one, two or four relay configs. I have two of the four relay units and I'm impressed !!

MSD 7566-2 MSD 2 Channel Relay Module

MSD relay modules are designed to be easily installed in most automotive electrical systems where a high amperage relay is needed. These relay modules are perfect use with high amperage electric fuel pumps and high CFM electric cooling fans. Each relay comes with a 40amp fuse, however lower amp...

www.holley.com

Available from Summit, Jegs, etc

 

[Don Frelier]

I've never used a relay for an electric choke.
I just pull it from the run wire on the ballast resistor.

 

[Sleeperbee]

I've never used a relay for an electric choke.
I just pull it from the run wire on the ballast resistor.

I've never used a relay for an electric choke.
I just pull it from the run wire on the ballast resistor.

I've never used a relay for an electric choke.
I just pull it from the run wire on the ballast resistor.

I need schooling and I need to add a few more facts. Stock ballast resistor and regulator removed b/c of MSD rtr distributor. I have installed a distribution block fed by a cable from the pos side of battery and am using that as a clean, non-switchable source of power for fan, Vintage Air, and horns. I need a switchable 12 volt source for electric choke and a control module for the Delta Pag fan (allows you to program when and at what speed the fan will run).

I probably don't know how a relay works. I thought I could activate the relay with the switchable voltage from the accessory blade (thereby using very little voltage) and the relay would then send the twelve volts from my battery cable/distro block that i installed.

 

[gkent]

I thought I could activate the relay with the switchable voltage from the accessory blade (thereby using very little voltage) and the relay would then send the twelve volts from my battery cable/distro block that i installed.

I think you misread the first reply. He's saying you can use that blade to trigger the relay.

You can then activate the relay via a switch using the accessory pin or somewhere else

 

[1 Wild R/T]

I think you misread the first reply. He's saying you can use that blade to trigger the relay.

Accept what the OP wants to do is straight up use that terminal as the trigger.. No other switch.... And he car 100% do that.... Essentially creating a switched power buss...
But my earlier point was why use a terminal inside the car to trigger a relay in the engine compartment when there are points under hood to get that switched signal... And there is a high current power source close by..

 

[bearman]

I'm missing something wants the electric choke via relay. The relay after powered up will either hold the choke closed or open depending how it is done. Shouldn't the choke be on a momentary switch. So once it starts you release the switch and drive away.

 

[Don Frelier]

I'm missing something wants the electric choke via relay. The relay after powered up will either hold the choke closed or open depending how it is done. Shouldn't the choke be on a momentary switch. So once it starts you release the switch and drive away.

An electric choke takes a little current to heat up a bimetallic spring.
As it heats the choke opens similar to the old stove in the cast iron manifold.

 

[1 Wild R/T]

As Don said, choke has a bimetallic spring... For those not familiar with the concept of a bimetallic spring as the name implies there are two dissimilar metals bonded together, one metal is selected due to it's property of expanding rapidly when heat is applied, the other metal is chosen because it isn't effected much if at all by heat... So when heat is applied in this case by a small electrical current passed through a resistance heating element the two dissimilar metals which are already in a coil react by tightening the wrap of the coil... The one end of the coil is attached to the choke, the other is anchored to the carb body... So that acts on the choke shaft and slowly opens the choke...

Be varying the voltage to the heating element you can tune how quickly the choke opens...

 

[bearman]

Never much of a choke guy. Living in az not much need for it. But learning something new is always worth the knowledge.

 

[bearman]

So next question po wants to run a fan and choke so why not just use a double throw relay. Wire one to 87 and the other to 87a on the relay just wondering.

 

[1 Wild R/T]

Never much of a choke guy. Living in az not much need for it. But learning something new is always worth the knowledge.

What, with the coming Ice Age you might need this useless knowledge

 

[1 Wild R/T]

So next question po wants to run a fan and choke so why not just use a double throw relay. Wire one to 87 and the other to 87a on the relay just wondering

Once the car is running he'll want to keep the choke heater running or the choke may close gain.. And he'll want to be able to cycle the fan based on coolant temp..

He could trigger one relay that powers the choke and powers the trigger circuit of a second relay... Then once again ground the trigger side of the relay through his temp sensor...

 

[bearman]

Once the car is running he'll want to keep the choke heater running or the choke may close gain.. And he'll want to be able to cycle the fan based on coolant temp..

He could trigger one relay that powers the choke and powers the trigger circuit of a second relay... Then once again ground the trigger side of the relay through his temp sensor...

It seems to me the way to go.

 

[1 Wild R/T]

It seems to me the way to go.

Not a bad choice... Though honestly as Don suggested earlier chokes have simply been tied to switched power at the ballast resistor for the last fifty years...

Use a HD relay to power the fan & don't worry about the choke..

 

[1 Wild R/T]

On my red Challenger I powered my twin two speed electric fans with a pair of HD relays rated for 100 amps each, necessary? No... But I've seen to many fan relays smoked to risk my engines cooling on undersized relays...

Tyco 100 Amp 12V Relay / Contactor / Solenoid LEV100 KILOVAC - LEV100A4ANG (3-1618389-7)

Tyco 100 Amp 12V Relay / Contactor / Solenoid LEV100 KILOVAC - LEV100A4ANG (3-1618389-7)

evdrives.com

 

[bearman]

That will handle the fan.

 

[DGE330/NC]

I've never used a relay for an electric choke.
I just pull it from the run wire on the ballast resistor.

i second the electric choke control from the Ballast resistor . champion radiator has a fan relay kit with temp switch ,