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Creating a new trailing ign harness. Questions.

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Old 06-15-11, 11:41 PM
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Jolly Green Giant

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Creating a new trailing ign harness. Questions.

1st of currently have whats left of the RX-7 interior out along with the massive expanse that is the wiring harness itself and while this weekend will be dedicated to depinning connectors and repairing any re soldering the FC fuse block back into the harness I have a couple of modifications I'm making to the harness and would like to get some consultation before they are attempted.

I'm going to be adding relays to a few much needed areas of the car mainly the fuel pump, ignition, and possibly obtaining the Black Dragon headlight kit after seeing much success with it's improvements.

As far as ignition is concerned my current setup is an MSD 6A and Stock trailing, now the trailing would not be an issue if it weren't for the fact that at some point the wires leading to and coming from the trailing coil were hacked and 'repaired' 3 times and I've had issues with it's stability since I got the car and since I'd like to run a switch panel to be able to turn the ignition off in 1 flick I'd like to create it's own harness or re-wire it so that I will be able to control it independently of the ignition switch.

My question lies within the wiring diagram...well specifically my lack of understanding how it's actually wired. Would anyone be able to either in words explain how the ignitor is wired up in conjunction with the coil or draw a different picture because in the FSM diagram it shows the power and ground wires overlapping for part of the diagram which just turns the entire thing into a mindf*** of nothingness.

The way it looks to me:
(Battery +) ----> (Coil +) ----> (Ignitor) ----> (Condensor) ----> (Ground)

If this is correct then great, I'm going to fuse and relay the trailing ignition as well as the MSD box given the open slots I have on the FC fuse block.

And then of course I plan to fuse and relay the Holley Blue Fuel Pump I'm going to order and possibly get the Black Dragon Headlight Harness.

A few pics of the current progress




Never again....

My entire interior sans seats

Before major stripping weighed 25lbs HVAC and Heater is all off to the side but estimated another 30 or so lbs.

Now, it weighs 8lbs

Template for center console arrangement

Ehhh ehhhh ehhhhhh???? lol not yet.
Old 06-16-11, 04:43 AM
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Round and Round

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Stock ignition wiring is very simple.

Green/yellow wire from trailing ignitor negative to trailing coil negative.
Green/blue wire from leading ignitor negative to leading coil negative.

Black/white wires for positive terminals of all coils and all ignitors are connected together and supplied with switched 12v from ignition switch.

Direct fire MSD is a little different of course. MSD box doesn't need a relay. Has a heavy gauge power wire and a smaller wire for switched 12v, so a relay is built into the box.

BD headlight relay kit wiring is fine. Relays are not sealed. They rust inside. Cheap ones from local parts stores are usually sealed.

Very impressive getting the main harness out. Did you have to cut any of the wires?
Old 06-16-11, 06:48 AM
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I need a cheaper hobby...

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so your dash with all the HVAC stuff weighed 30 lbs and now your down to 8? thats awesome! before i got my second fb, i was restoring my 83 which is halfway done with its turbo setup, but since I got my 82 decided i dont need all that fancy stuff and am stripping it. Im still keeping a full interior though.
Old 06-16-11, 09:30 AM
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Welcome to my hell... I'm doing the wiring on my 81 right now. Needless to say it's not my most favorite thing to do. There is a post on here that I contributed to the was called 12a minimalist wiring, might be useful.
Old 06-16-11, 12:36 PM
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You don't need trailing, ditch it
Old 06-16-11, 06:16 PM
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Jolly Green Giant

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Originally Posted by 74RX4
Stock ignition wiring is very simple.

Green/yellow wire from trailing ignitor negative to trailing coil negative.
Green/blue wire from leading ignitor negative to leading coil negative.

Black/white wires for positive terminals of all coils and all ignitors are connected together and supplied with switched 12v from ignition switch.

Direct fire MSD is a little different of course. MSD box doesn't need a relay. Has a heavy gauge power wire and a smaller wire for switched 12v, so a relay is built into the box.

BD headlight relay kit wiring is fine. Relays are not sealed. They rust inside. Cheap ones from local parts stores are usually sealed.

Very impressive getting the main harness out. Did you have to cut any of the wires?
Ahhh ok makes sense now, I figured as much with the MSD box as that's how it was setup before just wanted to be safe. Good to know about the BD kit.

Actually the harness came out pretty easily sans the headlights because the screws stripped holding the tops on and the 2 large connectors that go from the chassis harness to the dash that are pinched between the steering column and the firewall support, that took about 20 minutes, a screwdriver for prying and a few curse words to get out. Getting the actual dash out was the hardest part mostly because I'm 6'7" and sized like a brick house so getting up under the dash even with the seats out took some...careful maneuvers lol.

Originally Posted by cshaw07
so your dash with all the HVAC stuff weighed 30 lbs and now your down to 8? thats awesome! before i got my second fb, i was restoring my 83 which is halfway done with its turbo setup, but since I got my 82 decided i dont need all that fancy stuff and am stripping it. Im still keeping a full interior though.
Without the Gauge Cluster and Glovebox the dash weighed 25lbs but the other stuff taken out was the actual blower motor, heater core, HVAC tubing and the blend/mixing door console which I'm assuming weighed another 20lbs or so, so in all I imagine we've lost about 40lbs from that and losing the carpet and padding, what we lose from the harness is gonna be negligible but I mostly did that to tidy up the engine bay.

Originally Posted by 81WideMariah
Welcome to my hell... I'm doing the wiring on my 81 right now. Needless to say it's not my most favorite thing to do. There is a post on here that I contributed to the was called 12a minimalist wiring, might be useful.
Sounds good Yea I consider myself fairly proficient with wiring and automotive electrical but some of the stuff Mazda decided to do is just mind boggling sometimes

Originally Posted by t_g_farrell
You don't need trailing, ditch it
That's what everyone says and during the time I had it disabled there was a noticable difference once I hooked it back up especially in low end...dunno if it's because I'm only using stock coils instead of MSD Blasters but it was quite noticable, that and I'm running 26° Advance as set by the PO something I haven't and would prefer not to mess with. But it would make my life ALOT better

Now that I'm thinking about it I might actuall extend and run the alternator and dizzy wiring ontop of the motor back to the firewall with the transmission harness so I don't have wires jumping from the fender to the motor as that was one of my biggest peeves about how it looked before.

Here's how it looked before for reference.
Old 06-17-11, 07:57 AM
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Waffles - hmmm good

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Originally Posted by DarrenTRS
That's what everyone says and during the time I had it disabled there was a noticable difference once I hooked it back up especially in low end...dunno if it's because I'm only using stock coils instead of MSD Blasters but it was quite noticable, that and I'm running 26° Advance as set by the PO something I haven't and would prefer not to mess with. But it would make my life ALOT better
Its actually the ignitors AND the coils that determine how strong your ignition will be.
I run a Dell as well at about the same advance @4000 rpm. I didn't put the trailing
back in because I honestly couldn't fell it or hear a difference one I went with my
current ignition setup. See https://www.rx7club.com/1st-generation-specific-1979-1985-18/tfidfis-894669/ for
details.

Heres pic of how I routed my wires:

Old 06-17-11, 07:30 PM
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Hmmm, I'll look into it getting a pair of MSD Blaster 2s should do the trick but I'd also like to move the coils down closer to the plugs to shorten the wires...hell I remember seeing a guy build a coil on plug setup using bike coils and some crafty fab, looked very cool but can't for the life of me remember where I saw it. But anyway, I will have progress this weekend and I'll post pics, looks like I will just delete the trailing and I can always make a seperate harness for it later and tie it in.
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