21st Century Resto
It’s a mouthwatering combo, one GM should have engineered itself rather than leaving it to a clever chap from Cambridgeshire…
Meet the 3-litre straight-six Manta that should have been.
The Opel Manta, in either A or B form, is a fine machine. Capable, practical and handsome, it was GM’S answer to the
Capri and production ran for an impressive 18 years. There was a problem though, identified by many, even those who loved the car: insufficient fastness. The majority of Mantas, 2.0S included, could only make it to 60mph in around ten seconds. Not good enough.
So when, in 2011, Clive Moss found a rusting Manta B with a seized engine, he resolved to go further than the traditional Weber carb upgrade. In fact, he decided to get rid of the four-pot entirely. ‘It was in a sorry state,’ says Clive. ‘There was so much rust and the engine was completely locked up. I bought it anyway, because
I had always wondered what it would be like to have the straight-six Opel Monza engine in that car.’
With a basket case to start work on, Clive had no hesitation. He began his ‘big six’ experiment with a blank piece of paper. There was precedent, too: ‘Opel did have a notion to make one themselves.’ He’s right. Opel had previously tried a six-cylinder engine layout in a Manta A in the early Seventies, but it was deemed unsuccessful. Then the TE2800 arrived. It was the brainchild of a Belgian company called Transeurop Engineering. Transeurop took a 2.8-litre Cih-type engine from the Opel Commodore 2.8GS and popped it into a Manta 1.9SR. Sound easy? It wasn’t. The entire front end required reengineering. So Transeurop went back to Opel for help, but Opel refused to even allow the plucky Belgians to use their badge on the car. Transeurop Engineering then went to Steinmetz, Opel’s preferred tuning house. They supplied a new glassfibre bonnet with a large bulge on it to
make room for the engine, a set of widened arches, and a special front bumper integrated with the lower front spoiler, all to make room for the dramatic changes that needed to be made to the car’s front end construction.
The 79 TE2800S that eventually reached the road had 142bhp and could hit 60mph in 7.5 seconds. Steinmetz offered a racing version that put out 230bhp, which sounds much more exciting.
Clive agrees: ‘I wanted some of that. So, after lots of thinking and drawing, I worked out that I could make a six-pot fit, but the cooling would have to be squeezed a long way into the nose of the car.’
The theory worked for the TE2800S, but that was a Manta A. It worked on paper for Clive’s Manta B, but now it was time for a bit of practice.
‘Once I had the car’s original engine and box out, I sat it next to the 3-litre lump I had sourced from a scrap Senator,’ he smiles as he remembers. ‘I could see that, with the Monza gearbox, the ‘six’ would fit with some alterations to the main engine mounts and anti-roll bar.’ Clive has the eye of an engineer… he also owns a tape measure. This was employed on
multiple occasions before he finally bit the bullet and started work in earnest.
The shell was very rusty, but Clive is a dab hand with a MIG welder and it only took a few months to get it ready. ‘Once the shell was restored it was time for paint, and there was only one option really. Something close to the yellow used in the Manta 400 rally car livery of the early Eighties – and black stripes and lettering to my own design.’
Once Clive had finished the paint the GT-J, as he had christened it, was ready to receive the new powerplant, so Clive went to look for a good engine. ‘At the time I had a Senator automatic. I also had the Getrag 264 from a four-speed Monza. I fitted them together and then, with some alterations to the gear linkage I discovered that, give or take a few millemetres, the new box would end up in the same place as the original four-speed Opel 2.0 set up.’
Dropping in
All that measuring and thinking time was paying off. New engine mounts were fabricated and the 3-litre, six-cylinder lump and its Getrag ’box were lowered in. The fit was remarkably good, but any radiator would need to be tucked deep into the nose – the rocker cover ended ten centimetres from the slam panel, so it was a really tight fit.
‘Once it was in I could start work on the cooling system,’ sayas Clive. ‘I had to work out what size radiator I needed and where I could add the fans.’
‘I designed and built my own cooling system for the Weber carbs’
Eventually Clive used a radiator from an Audi 90 Quattro. ‘It was shallow enough to fit deep into the nose of the Manta, but was hefty enough to cool the engine properly.’ Clive mounted it into the nose on an angle to make fitting the fans possible… the fit is almost invisible.
Clive’s next challenge was to work out the braking. The rears were simple, as he kept the same set up but removed the load bias valve. ‘The change in weight was all up front, so I made Audi discs fit the original hubs and then fitted reconditioned Monza calipers. After that, I realized I was getting there.’
Clive had the original interior trimmed with yellow piping to set off the body colour. After two years solid work he had a car that was looking great, but needed finishing. Clive was up for the challenge. ‘I designed the decals and found the alloys. Then I realised I needed better springs and found some through the club that were for a Manta 400 rally car – they were perfect for the extra weight.’
The time for start up was approaching, but Clive made a last minute change. ‘I decided I didn’t want the fuel injection, I wanted triple carbs. So I remade the inlet manifold and fitted triple Solex C45s that came from a boat engine.’ Sounds involved, and it was, and to be fair Clive encountered lots of problems getting them to work, so he went traditional and bought three new Weber 40s with standard jets. He didn’t leave them standard though. ‘I redesigned the linkages and suddenly, on first start up, it was almost perfect.’ There were still issues with cooling though.
‘I knew that the tight space and the big engine would generate a ton of heat and that, with carbs, either Solex or Weber, I would be in danger of having and engine that would have trouble fuelling itself in hot weather. So I designed my own carb cooling system.’ Of course he did. Clive is no ordinary restorer. ‘The carb cooler is a 12v boat bilge pump that blows air straight onto each of the Webers.
It is switched on by a adjustable thermoswitch from the heater hose. It works on the same principle as the cooling fans. I made the pipework out of an old exhaust.’ It was ready, so Clive drove it to the MOT station. ‘There I was,’ he says with pride, ‘This was my Q-car. A unique Manta GT modified with a 3.0 Vauxhall Senator six-cylinder lump on triple Webers. And suddenly I was allowed to drive it!’
Hats off to Clive, he has a real autobahnstormer that retains the svelte Manta look and feel, but goes like stink. ‘I’ve been showing the car at a few events and every one I take it to ends up with swarms of people having a look,’ he smiles, ‘they are all interested in the design of the engine set up. I’m glad that I had success where Opel didn’t.’