There's at least 160 mph and 0-60 in 4.2 seconds in there somewhere..!

 This section deals with all things Wiring:

  1. Main Loom
    1. Loom Configuration
    2. Engine Bay Wiring
    3. Relays
    4. Fuses
    5. Ignition switch Configuration
    6. Boot Wiring
  2. Dashboard
    1. Layout & Loom
  3. Wiring, Connectors & Terminals
    1. Loom Cable
    2. Connectors
    3. Terminals
    4. Solder
  4. Power Distribution
  5. Fixing & Fitments Comments
  6. Wiring Modifications

1. Main Loom

I've worked through the two looms; the dash' and the main loom, and I have identified and labelled all the wires. Depending on how I design my dash' or some other bits, I might have to extend some wires. This will not be an issue as long as I use the correct type of wire [ampere wise.] I'm not going to buy a multitude of reels of different multi-coloured wires to colour-conform with what I'm extending, I'm only going to get a reel each of black and grey. Black being the common for ground (gnd) and grey being a colour not used as a primary identifier for anything. So anything grey will trace back to the feeder colour, and black is black.

For neatness and safety I've also invested in the correct size terminals and heat-shrink for the different wire sizes. This to ensure a proper connection and to neaten everything up and to make sure there is no exposed metal or wire. 

I've measured the various diameters of the clusters of wires on the looms and have bought a selection of stainless steel "P" clips. I went for 6 mm, 8 mm 10 mm and 16 mm clips. Also, As I'm going the Speedhut, not the Smiths route for my gauges, some of the dash' loom will be redundant as the Speedhut gauges us a series, feed-through power and ground and lighting set-up. But first I'll have to do some amperage/wire spec' calculations... Don't want a melt down when on a run.

As previously stated I'm going the MSD Atomic EFI route for my Ford 302 (not the carb' route,) and I've been thinking about how to hook up the sensors; but in reality the sensor-to-gauge hook-up principles will be the same no matter what engine or gauge type I use, so the amount of head-scratching and fiddling and tea drinking should be about the same.

i. Loom Configuration: There are three [functional] parts to this loom. The main demarcation being the big rubber engine bay grommet. The three loom parts being:

  1. Engine bay wiring
  2. The wadge of wires feeding the bank of relays, the fuse box and the plugs that join everything up
  3. The wires that go into the boot

(More detailed views are in the Electrics - Looms Album) 

ii.  Engine bay wiring: I've seen many ways of routing this line of wires, and I've fixed mine to the inside edge of the engine bay, mostly tucked away under the bonnet lip. Then, fixing the remaining o/s wires to and across the bonnet hinge retaining bracket. For this, I used a combination of 6 mm, 8 mm, 10mm and 16mm steel "P" clips.


iii. Relays:

First I fixed in place the bank of seven relays. But, I wasn't happy with just self-tapping these to the bulkhead as it wasn't flat, so I mounted them onto an aluminium back-plate. This back-plate being secured to the bulkhead by two mounting brackets and a couple of M5 bolts. A very generous half a day's work but it was worth it as it is now easy to detach the whole bank of relays 'as-one' (if I need to.)

I toyed with the idea of having a bank of 8-10 relays but there is only enough room for seven [comfortably] in a row. I will need at least a couple more; one for the Pilgrim starter button and one for the heated seats. I do, however, have a spare in the supplied bank of seven as I won't be using the amplifier relay (relay nr 1.) So am undecided what to do at the moment with this one.

Made the mounting brackets from a steel bar. A piece of square steel tube would have been perfect, but I didn't have any. Each bracket consisted of a couple of 10 cm lengths of steel. The first having an M5 thread tapped into it, and the second an M8 hole. The second piece to provide a bit more distance from the bulkhead as it is slightly concave. The two individual steel bracket elements were epoxied together and fiberglassed onto the bulkhead, and the relay back-plate was bolted in place (with the relays bolted onto it.) Everything ended up flat and level and secure, and is now easily detachable... job-dun.


I also made another relay bar to takes four extra relay units. This for the 40 amp starter button relay and maybe the heated seats relay; which leaves a couple for future use. Notice also the 50 amp master fuse holder is on a metal backplate. Am really not a fan of having electrical weak-spots in direct contact with GRP or plastic.

The two bus bars (just below the heater outlets) are for common distribution of 12v live from the battery and 12v switched power from the ignition cylinder. This keeps all the 'same' in the same place. And finally I've installed an additional eight unit fuse block. This single provided block of eight really is not enough.

So... all the electrical safety and distrubution gubbins are located high up in the passenger well. Am happy with this. Now I can get cracking and join it all up...

iv. Fuses: I've put in an additional 8 Way fusebox. This is a stand alone unit similar to the one that came with the loom. Eight fuses are really not enough, so having a second unit in the same place as the original makes it easier to electrically manage things; and any future additions will be easier to incorporate into the system.


v. Boot Wiring: The wires for the boot i.e. lights, number plate etc. are fed in from the tub. And Luckily I didn't need to cut a chunk out of the [passenger side] cockpit back panel to feed the wiring into the boot as there was a small hole going from the boot into the cockpit area at the perfect position. This was where the body was joined to the tub. There was a small gap where there was no fiberglass. Not sure if this was an intentional gap, but it worked for me.

So, from within the boot, I filed and smoothed the rough edges of the hole and made it a bit bigger. Then I fed the wires through from the cockpit side. It was a bit of a squeeze getting the fattest bit of the loom through i.e. the bit where all the wires congregated at the widest "Tee-off" point, but a few well-chosen expletives on my part got the job done.

This picture shows all the boot hook ups for my installation. Notice the double-earth reverse and fog lights [blacks] plugged into an unsued earth. The bunches of wires (top left) are all surplus to requirement. Also, I've no need to use the offside fog and reverse lamp (RY & BN) connections as these are just extensions from the near side cluster.

v. Ignition Switch (Configuration): I've sourced a proper (female) connector plug for the Vauxhall (male) terminal plug on the ignition switch. And I've worked through the switch terminals with an ohmmeter to see what's really happening.

The 'proper' plug was sourced from my local scrappy (best fiver ever spent)

The colour coding, and indicated use, is from the GD documentation

(Plug 'A' (Ign switch plug) on the main loom)


It seems the only terminals I need to be concerned about are terminals 3, 4 and 5. These being live for key position 2. This being the return position after crank (which I won't be using.)

Three options for connecting things up (as far as I can make out):

  1. Connect up all up and wing it
  2. Distribute the load over the whole ignition switch
  3. Have a bus bar in place to distribute the 12v switched live from a relevant ignition key position

Option two is doable but I like option three as it will feed all the dependent 12v switched devices at the same time, and from the same place. However, I will be putting the ECU on its own 12v ignition feed. This is because if the ignition is off, and the fan kicks in, the fan motor will create [induce] a back current which could (according to MSD) burn out the coil if they [the fan and ignition] are both on the same circuit. So I'll be directly connecting the 12v switched ECU power wire to its own feed terminal on the ignition switch.

2. Dashboard - Layout and Loom

As the dashboard is the life-support monitoring and awareness centre for nearly everything, I've documented all things "dash" within a separate and specific Electrics - Dashboard page. There is some overlap e.g. steering colomn and fitting, but essentially the dashboard needs it's own separate documention as it' brings everything together.


3. Wiring, Connectors & Terminals

i. Loom Cable: The majority of the loom cable consisted of just two sizes:

  • 16.5 Amp Thin Wall Cable (30/1.93 mm (best estimate))
  • 25.0 Amp Conductor Spec (28/2.46 mm (best estimate))

I needed to source a supply of cable for my modifications and extensions. Black for gnd (16.5 & 25.0 Amp sizes); and gray (also 16.5 & 25.0 Amp sizes) for everything else. Gray being not a primary colour on any of the looms and of which can be traced back to the original it's joined to; and black is black... I could have bought a selection of colours to match things up, but as I didn't know how much I would need of each colour and wire size, it made sense to just get a good length of a single colour in the sizes I wanted...

ii. Connectors: A pack of Lucas style bullet connectors came with the main loom. Also, the lights and some of the loom endings had brass bullet fixings already crimped on the ends. And having seen how these function I was not happy as they are very exposed and susceptible to all sorts of environmental influences; and during my effort to fit them (before I made the decision to consign them to the bin) I had to bend some of the connector sockets to make the bullet end fit... I really was not impressed with these so I changed them for more robust spade connectors.

iii. Terminals: It might seem a bit of overkill to write about terminal sizes, but I found that if the wrong size was used i.e. if the bit you crimped was too big with respect to the wire size that was being connected, I found the hold on the wire was doubtful to say the least. So I bought the correct terminal size for the wire size I was using... I had no idea you could get different sizes depending on wire diameter, but I'm glad I discovered this early on:

Terminal types and sizes used:

  1. Spade (Open Barrel Female): (Clear plastic sleeves were used on these too)
    • 6.3 mm: These for the 25 Amp cable or for when I needed to join two thinner 16.5 Amp wires to the same connector
    • 4.8 mm: For the 16.5 Amp cable
  2. Male Blade Terminals:
    • Blade Width / Cable Size: 4.8mm / 0.5 - 1.5mm²
    • Blade Width / Cable Size: 6.3mm / 1.5 - 2.5mm²
  3. Ring Terminals:
    • 5.3 mm hole diameter for cable size 0.5 - 1.5mm²
    • 5.3 mm hole diameter for cable size 1.5 - 2.5 mm²

ivSolder: Did some practice soldering, and I'm glad I did as this seemingly routine [and background] activity could have turned out to be a major problem area. I had restocked (from e-bay) in readiness for me joining-up my car's electron-providing arteries, and it was absolute rubbish... An utterly crap product. It wouldn't take to a wire like the stuff I was just about to run out of, and when I did manage to get it to wick into a wire using what I considered as extreme heat (this being I had had to hold the iron on the wire for what seemed like an age,) it dried with a milky, hazy surface; not a shiny one as I'm used to.... I was not happy with this at all..!

This milkiness could be attributed to a couple of things:

  1. Lead free solder... This was not the case as it was supposedly not lead free; so I discounted this as being the cause. Note... I didn't go the lead-free route because there is a greater risk of it not creating such a good electrical connection.
  2. Poor quality solder... Am going with this one. It was supposedly a 60:40 tin/lead mix, but as I have no way of confirming this I will never know.... It's in the bin.

So... having dumped the milky stuff, I sourced some nice silky 60:40 tin/lead solder locally, and it was as pleasure to watch it caress and flow around and into the chestnut coloured strands, it, congealing sedately and serenely creating a very shiny and very conductive joint (I really need to get out more!)

Made a very useful pair of helping hands too... 

4. Power Distribution

This is where I am at the moment

5. Fixing and Fitments Comments

  • When fixing the connectors, I used heatshrink (the type with the inner adhesive lining); and I topped this off with a plastic sleeve on the female side. That, after I wicked some solder into the crimped joint... (Total over engineering, but I'm happy with the outcome)
  • As I've routed my front lights wiring and the engine loom along the inside of the engine bay, there is no possibility of the joints getting sprayed with water or muck from the wheels. So the plastic sleeve protected connectors are more than adequate for the job
  • I also put PVC cable sleeving on all exposed i.e. the two wires from the front indicator lights are now all contained within a single PCV sleeve
  • The only exposed connections are the earth bullet types on the front indicator lights. Not sure what I'm going to do to protect these from the elements yet
  • When crimping the ring terminals I found the insulation tended to split. Not happy with this so I replace the insulation with heat shrink. Not too big a job and it allowed me to wick a drop of solder into each joint as an added holder and conductor. Now there is now no confusion as to any colour coding convention with the blue/red/yellow ends (they're all black)

6. Wiring Modifications

'gnd' Wire Modification in Relay nr. 5 (Horn): My first modifcation was to a wire in relay nr. 5 (the two joined purple ones.) This to provide a required gnd [return]. The original configured purple was looped from terminal 30 (12v live) back into terminal 85 (gnd) so there was no gnd return in the relay. Spent ages working out how to do this only to find that, had I taken the cable management tape off first I would have noticed the gnd feeding relay nr. 7 had been fed from relay nr. 6. I assumed [wrongly] that each relay had its own gnd wire.

Snipped off the surplus-to-requirement purple wire and replaced it (in terminal 85) with a gnd extension from relay 6; which I continued and looped it into the gnd terminal of relay 7 to complete the modification. Bit of tape to neaten it all up and job done.



MSD ECU Fan Control: I modified the GD fan relay wiring (relay nr. 4) by replacing the black/green (gnd (85)) with the ECU fan control gnd wire (the pink wire.) The ECU takes care of the fan implementation as it also has the feed from the water temp' sender.

There is also a facility to control a second fan or a booster capability on a single fan from within the ECU, so everything is in place for future tinkering.

Washer Pump: The washer pump was originally configured as a 'switched earth'. With the Vectra steering column this becomes a 'switched live'; so the green wire needed to be replaced with an earth. Took the earth from an unused gnd from the dash loom... Neatened up the wiring a bit too.