Episode 9 of Retropower’s Gordon Murray Mk1 build marks the end of the metalwork. Before the shell goes for paint, the team designs a custom dry sump tank and plans every pipe and wire so the painted shell won’t need new holes. Then the shell is blasted, zinc sprayed and primed.
Video: Retropower on YouTube · watch “Gordon Murray's Mk1 Escort - Retropower Build Episode 9” on YouTube
What happens in Episode 9
Metalwork complete (0:50). After a long run of small final details, the metalwork is done. The shell has been blasted and zinc sprayed underneath, and the outside is in epoxy primer. It’s now with the bodyshop for seam sealing and paint prep.
Designing the dry sump tank (2:10). The tank couldn’t go on the other side of the engine bay because of the airbox, and the team didn’t want it in the boot. Hot oil lines through or under the cabin aren’t ideal on a road car. So it goes in a front corner, partly recessed into a reshaped inner wing that still clears the wheel on full lock. The team made a CAD model, then a steel mock-up. The final tank will have a billet machined top and base with fabricated sides. Oil returns from the engine through the cooler in the front panel. It enters a swirl tube built into the top, then drops through baffles with aligned holes, so you can look down to the bottom to check the level or clean it out. The base has mounting bosses, an outlet, a drain and two sensor holes (one for the gauge, one for the engine management). The Cosworth engine’s scavenge pump is internal, so a single feed runs from the tank to the sump. A breather tank sits in a spare space behind the headlight.
Plumbing and wiring planned now (10:05). All fuel, brake, oil and coolant lines and every wiring route are planned before paint. Nothing passes through rubber grommets in the bulkhead. Pipes use aluminium bulkhead fittings, and the engine loom separates from the car at motorsport-style bulkhead connectors. Rivet-nut holes and welded studs carry the clips. The fuel pressure regulator sits low in the engine bay. For symmetry, the screenwash reservoir in the bay matches the brake and clutch reservoir, but it feeds a larger tank that doubles as the passenger’s footrest.
Rear of the car (14:12). There are mounts for the battery tray and the fuel tank, plus inserts for the fuel pump and filter, which a trim panel will hide. Bonded aluminium panels separate the boot air from the cabin air, because the fuel system lives in the boot.
Lead loading (16:17). The original factory joints at the scuttle and pillars are lead filled and shaped. One scuttle seam is leaded, then the seam line is cut back in, so it looks original but can’t crack or let rust creep out.
Zinc spray (17:49). The underside is bright silver from molten zinc sprayed by an oxy-propane gun fed with zinc wire. The same kind of process is used on offshore structures and bridges, and it protects the steel even where it’s scratched. It will be covered with a tinted urethane coating. The team prefers blasting to dipping, because dipped cars tend to trap rust between closed seams. Cavities will be wax injected at the end. The team also explains that every seam was TIG brazed before blasting. Brazing is a little softer than welding, so it’s less likely to crack, and the TIG torch keeps heat and distortion down.
Colour and a postcard (21:24). The car will be painted an original Ford white, a fairly creamy shade. After his last visit, Gordon sent a handwritten postcard saying he enjoyed it.
Parts, tools and suppliers mentioned
- Custom dry sump tank (CAD design, billet top and base, fabricated body) and breather tank
- Cosworth engine with an internal dry sump pump; oil cooler in the front panel
- Aluminium bulkhead fittings and motorsport-style bulkhead wiring connectors
- Rivet nuts, welded studs, threaded inserts
- Thermal zinc spray, epoxy primer, seam sealer, lead loading, TIG brazing, cavity wax
Lessons for your own Mk1
- Plan every pipe and wire before paint, so the finished shell needs no drilling.
- Bulkhead connectors make engine-out jobs easier than looms pushed through grommets.
- Think about access to the dry sump tank. Being able to see the bottom helps after an engine failure.
- Separate the boot from the cabin if the fuel system lives in the boot.
- Closed seams trap moisture. Seal them and wax inject the cavities.
Mk1 context
Escorts usually carried a dry sump tank in the boot when they had one. Retropower moved it to the engine bay here, which is unusual on a Mk1.
Related
- Series hub: all Retropower Gordon Murray Mk1 episodes
- Background: the complete history of the Mk1 Ford Escort
- More builds on video: Mk1 Escort build videos