30amp single pole double throw 12v DC relay

[74 360 dart sport]

Msd addendum for run ready distributor the relay from msd is 36.99 I dont know what the single pole double throw high energy means but wouldn't a guy be ok with a Bosch relay for 10.99

 

[Dana67Dart]

single pole double throw

Single pole= one common contact
Double through = one contact is normally closed and one is normally open.

Double pole = two common contacts (like two switches in one)
Single throw = only one output contact either normally open (NO) or normally closed (NC)

 

[Mike69cuda]

Single pole means it can only switch one circuit.

Double throw means it can connect the input to either of two outputs.

Any 30 amp Single Pole Double Throw (SPDT) relay should work, providing it operates off 12V.

You can probably get a better explanation by searching on the internet.

People love to sell you the $5 part for $50 because it says MSD on it.....

 

[Dana67Dart]

What mike69cuda said.

He explains it MUCH better then I did.

 

[67Dart273]

Why do you need such a thing? Ignition should be either on or off

 

[70 Buster 340]

I think the MSD concern is 'run on' if using an alternator

 

[67Dart273]

An MSD will not run on in a Mopar if properly wired IT IS sometimes a good idea to put a relay---fired by the ignition switch "run" line......and used to feed underhood loads like the VR and ignition to avoid drop problems

 

[74 360 dart sport]

Yes msd says with the relay it will always have 12 volts with no surges up or down

 

[67Dart273]

Yes msd says with the relay it will always have 12 volts with no surges up or down

Well if you are running an MSD CD ignition box that makes absolutely no sense. The MSD CD box has a "big black" and a "big red" which are the main power and are to be run directly to a full time battery power. The "small red" switch lead already works much like a relay--it triggers the unit on, and requires very little power

Where exactly are you getting this information, link to a document, etc?

 

[BillGrissom]

Surely a standard 30A Bosch relay suffices to power the ignition module. I do that. In all 3 1960's Mopars, I installed an underhood fuse/relay box from a late 1990's Jeep, as you can see on the L firewall of my avatar (1965 Dart). One of the many relays is for "IGN" power, which has several consumers in the engine bay (Vreg, HEI module, EFI controller, ...). It routes via a screw terminal for easy distribution and trouble-shooting. The other relays are used for things like starter, horn, headlamps, fuel pump, ... which replaces the OE clutter of special relays on the firewall. I was also able to run slim 20 awg ribbon cable from bulkhead connector to the relay box for most wires.

 

[74 360 dart sport]

I am not running a box the info I got from a msd tech

 

[67Dart273]

Oh **** I see now. All you need is a generic Bosch relay. Cut (electrically) the dark blue IGN1 "run" line where it comes out of the bulkhead. Take the firewall end and key a Bosch relay. Pay attention to coil polarity as some (most) relays have a spike diode across the coil. Feed the power contact from say, the starter relay stud, with some sort of protection, 20-30A fuse etc.

Now feed all underhood loads off the switched contact, the VR, the alternator field, and your "ready to run" power. Get rid of the ballast if so recommended. If so, take the IGN2 (brown) and hook that over to coil+/ and the MSD power