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In 1998 I bought a Triumph Herald 13/60, here you can read about it's restoration and share in a few photo's from it's travels. Please feel free to leave comments to any of the posts, of even email me if you want to.

Sunday, February 26, 2017

Converting a Triumph Herald to EFI (Part 3 - Fuel)

Depending on your fuel tank arrangement, you may have to add a swirl pot (or similar) to stop fuel surge. Fortunately a Herald/Vitesse tank is tall and thin and its base dips downward towards the rear, this allowed me to avoid any major modification. All that was needed was to remove the drain and replace it with a 3/8" NPT bung/barb which would exit into a strainer/pre-pump filter, then onto the high pressure pump, both of which were to be mounted on the boot outrigger.

Tank modification
I added a spread of epoxy/chemical metal to help seal up any pin holes around the area which had been welded.

Welding tidied up and barb fitted
The tank was then treated to a sealer kit from www.frost.co.uk as belt and braces against any leaks, then painted.

Tank painted prior to fitting
The fuel feed follows the original routing along the chassis into the engine bay and through another filter and onto the Fuel Rail.

Filter on the supply side
The Fuel Rail extrusion is available in 2ft lengths from various suppliers. First this was to cut down to roughly the right length, which from memory was around 11". The spacing's for the injector holes in the rail need to match those on the inlet manifold, so after measuring carefully several times I marked where they needed to be.

I used a 13.5mm drill for the injector holes and a 11mm for the step within, this was done on a friends pillar drill. Trying to get the drills not to wander was tricky, but after much experimenting with various pilot drills, we finally got there. If I were to do it again, I think I'd use a local engineer with the right equipment.

The internal bore of the rail was 0.5", so it needed tapping to 9/16" UNF to take a suitable AN-6 fitting. No room for error here, so I entrusted this to a local engineer who machined the ends to ensure they were square and flat, he then tapped the thread.

Fuel Rail
Correct fuel pressure is vital, around 3 bar is needed, so a regulator was fitted on the return line. I was struggling for suitable locations so ended up mounting it on the heater box. This makes removing the oil filler cap a bit fiddly, but to maintain bonnet clearance I couldn't raise it any more.

Fuel Pressure Regulator
The original fuel line was replaced with 8mm pipe and acts as the fuel return. This was still connected to what was originally the fuel pick-up, as this is low down in the tank it was ideal for the return entry and would minimise any air bubbles in the fuel.

So once all the pipes and hoses were in place and all unions tight, it was time to power up the pump, adjust the fuel pressure (this should be done with the pump on but not with the engine running) and check for leaks, fortunately all was fine.

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