As previously stated, I really didn't want a carburettor perched on my Ford V8 as I didn't want the hassle of babysitting it. But I did want to retain the traditional 60's look whilst taking advantage, and having the benefits of a hi-tech fuel and engine management system.
So with the criteria set in stone, I opted for the MSD Atomic ECU/EFI unit. This is a square-bore carb' lookalike unit that sits where the 'traditional' carb' sits, and it contains all the sensors and gubbins to provide total electronic fuel management.
The package comes with everything you need: i.e. the main square-bore bolt-on EFI unit; fuel pump; fuel filters; high-pressure fuel pipe, an SD card to update from the web, and all the fixings. It also has a very nice looking Power Controller Unit "black box" [which is red] and a plug-in hand-held controller which allows you to alter and tweak things without a laptop. I also don't need to relay or fuse this as it's all taken care of internally.
And, as I didn't want to hide the Power Controller Unit away, I put it on the firewall next to the fuse boxes... If you've got it, show it.
The ECU/EFI (MSD Atomic PN2900) Kit:
- Electrical Connections:
- Engine Coolant Sensor
- MSD Power Module
- Fan (ECU (pink) wire to Fan relay)
- 12v Switched Ignition
- 12v Live (battery)
- O2 Lambda Sensor
- ECU to fuel pump (Power)
- Fuel pump to gnd
- No fuel return
- A ‘soft’ fuel line is required (so as I didn’t need to use the fitted GD copper one I took it out)
- Tachometer hook-up from HT coil
A GD placement for their fuel pump and filters is just behind the diff’, and they [GD] can provide a very nice laser-cut plate to mount them on. However, I’m not going to use this position because, as my MSD fuel pump and filters have compression fittings and run ~38 psi on idle, and in excess of 70 psi when I’ll have a wide grin on my face and blood rushing to my right foot, I won’t be comfortable having this kind of fuel pressure in a high-pressure rubber hose with six compression joints sitting in close proximity to a couple of very hot exhausts. And also I don't want the pump exposed to the elements.
So I’ve mounted the pump and filters in the boot. This also provides good access and keeps all the potential weak points centralised.
My MSD configuration is for ‘no return, and as the pump is of the “Pulse Width Modulated” type I cannot have hard (copper) fuel lines. Apparently, because of the pulse-on-demand control, the rubber hose ‘cushions’ each pulse thereby not stressing the pump. (Something similar to the condition of “Water Hammer” in domestic plumbing systems.)
Fuel Hose Pipe: The high-pressure hose-run is from the square-bore throttle body, along the top of the chassis frame and into the boot; the entry point being at the same place as the GD configuration.
The fuel hose is a single run of ⅜ inch, 225 psi rated Nitrile rubber, but the tank outlet is an AN-8 (½ inch) male union. So I need an AN-8 (½ inch) to AN-6 (⅜ inch) in-line converter, about a foot of ½ inch pipe, and a couple of AN to barbed compression unions to make it all work.
To further protect the hose [that being the hose-run directly above the drive shaft] from any muck or flying debris, I’ve encased it in a larger 24 mm O/D, 4-ply, reinforced silicone hose. I did consider a steel braided sleeve, but, as any impact from flying debris could cause the impact point-of-contact area to directly absorb the majority of the energy, the extra 4 mm of reinforced silicon shielding surrounding the fuel pipe in my humble opinion is a better solution (in this instance).
Fuel Pump & Filters
I fashioned a 2 mm mild-steel platform to mount the filters and fuel pump on. This platform also ensures the pump is in line with the bottom of the tank (as per the MSD recommendation).
Power and Triggering: Power and [fuel-on-demand] pulse triggering is achieved by a direct single-cable connection to the ECU controller.
Positioning: Trial fitted the fuel tank in the boot, and I decided to reposition the two retaining straps to the outer edges of the raised centre part of the floor. A total move [inwards] of about 5 cm for each strap.
Insulation: I used 25 mm x 10 mm foam strips for the bottom and 25 mm x 6 mm strips on the back of the tank. I also stuck some 2 mm rubber sheeting on the underside of the straps to insulate those from the tank too.
Retaining Straps Positioning: When I measured up for the retaining bolts, I had a concern with the positioning and proximity of the securing bolts, as they would have been virtually touching the top of the silencers. There was only ~0.5 cm clearance for the nyloc nut and load-spreading washer which really wasn’t enough for my liking. Moreover, I was not happy with the nyloc being so close to the heat source.
Making the Retaining Straps: Bending and fitting the steel retaining straps was interesting, and I became aware very quickly about “bend radius” and how the straps needed to follow the angles of the tank. The strap shape at the edges had to be a proper fit otherwise the majority of the holding force would have been on the corner point of contact... Not good.
Made an aluminium strap template and marked up where the bends were to be (allowing for the radius,) then I bent the lower bend and got that to fit properly with some judicious use of a club hammer. Then I re-verified the upper bend location and judiciously bent and bashed (on the workbench obviously) to obtain the correct fitting.
Bending the steel straps was done by clamping the strap in a homemade jig. Essentially the jig was a couple of pieces of angle iron with bolts at each end. Bend procedure was: heated up the area to be bent, then, by further clamping the piece between two additional metal plates to keep it as flat as possible, I made the bend... Then I finished the finer detailing with the club hammer.
Fittings were socket-head bolts, nylocs and large load-spreading penny washers.
So the tank is fully insulated from any contact with metal or GRP and it is firmly and snugly cushioned and positioned, and there is nothing protruding into the boot area or in close proximity of the silencers... Am happy with this.
Fuel Filler Pipe: The filler pipe is a very nice 50 mm Nitrile rubber hose with a wire spiral inside the wall to allow it to be flexible enough to bend to the optimum angle without creasing. I also put a very thin smear of Permatex fuel-proof gasket seal in both ends of the pipe. Securing was with a couple of jubilee clamps at the tank end and one at the filler end.
Earthing the Tank & Filler Cap: The tank and the filler cap needed to be earthed (IVA requirement.) This was achieved with a direct wire connection from the gnd-bus. Securing was to the base of the tank filler inlet (via a clamp), and then on to one of the filler-cap fixing bolts.
Fuel Tank Sender
Fuel Tank Sender Wiring: The fuel sender is of the ‘resistance’ dip-stick type (Speedhut), so the power, gnd and sender terminals are all located on the top plate. And because of this, a wiring modification was needed so I extended the 12v switched ign’ feed wire (dash’ loom L17 (green)).
Also, the gauge wiring, i.e. the sender and gnd wires (white & black) are connected directly to the dashboard loom sender and gnd wires (L17 Green/Black and Black). So now, all the GD loom L17 sender and power wires are remoted to the boot.
Accelerator Cable Throttle Stop
Requirement: I needed an accelerator pedal stop... As I’m ‘driving-by-wire’ a pedal stop is important as it takes all the strain off the throttle linkage if and when your foot goes to the floor. In the case of a carb’ or as in my case the MSD square-bore EFI, putting your foot to the floor would cause strain on the linkage end. This is because the pedal box 'travel' is deeper than the necessary amount of pedal travel.
Production: My solution was to make an adjustable accelerator pedal-stop out of an M10 bolt, a couple of nuts, a large penny washer, some sheet rubber, and a piece of steel plate… The throttle cable is a bicycle brake cable, and the outer sheath is a bright yellow to match the HT leads and heater control cable.
Specifically, I fashioned a small backplate, welded an M10 bolt to it and drilled the plate for an M6 [bulkhead] securing bolt. The long M10 bolt being the functioning and adjustable ‘stop’ which is secured with a locking nut. The pedal stop backplate sits directly behind the pedal, high’ish up the lower arm so as to be out of the way.
Adjustment: I needed to facilitate a throttle cable travel of 5 cm… But! The throttle pedal armature only allows for a throw of 3 cm. This is because the length of the accelerator pedal arm (above the fulcrum point) is shorter than that of the below armature (this being the distance from the fulcrum point to the pedal.) So, with this differential to deal with, measuring the pedal travel to create a 5 cm cable travel worked out to be, I needed it to depress 7 cm... Not concerned with this difference as it means the car will be less twitchy.
Lastly, the accelerator pedal's resting position will be 4 cm lower (further forward) than the clutch and brake pedals. This is how it is on regular cars so that’s good enough for me…
Below is a nice view of the Power Controller and MSD Air Cleaner and Coil. You can also see the throttle cable running from just below the high-pressure brake & clutch hoses, around the back edge of the engine bay, to the carburettor.