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Rover 3500 (SD1)

Published: 4th Jul 2011 - 1 Comments

Then & Now

Rover’s fi rst offi cial International motor sport entry was somewhat of a damp squib, with Tony Pond and co-driver Rob Arthur exiting the 1984 Lombard RAC Rally on the fi rst special stage with a front wheel hanging off the SD1. Still, the following year Pond proved he could master the car’s power on asphalt rallies with some stirring performances in the British Rally Championship. It was left to David Price Racing, Tom Walkinshaw, and Andy Rouse, amongst others to prove the Rover’s real talent on the tracks. Rouse won the British Touring Car Championship outright in the car in 1985, whilst TWR won the Silverstone Tourist Trophy race in ’83 and ’85, and in ’85 Tom and Win Percy fi nished third in the European Touring Car Championship after six wins. Back in those days, most of the tuning gear for the V8 came from the USA, courtesy of people such as Crane Cams, Edelbrock manifolds, and Holley carbs. Now Rpi Engineering (www. v8engines.com) are top tuners in the UK, whilst Rimmers Bros (http://www.rimmerbros.co.uk) has all the spares you could ever want.

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Which classics still have the potential to get up and go? Paul Davies remembers the cars, the people… and how to make a classic hot car!

If the 2000 ‘P6’ of 1964 was the car that helped Rover break away from its ‘Auntie’ image, it was the ‘SD1’ of 1976 that helped put the famous British manufacturer into terminal decline. Which was a pity really, because it was a jolly good car. Fastback styling by David Bache – with, some said, a hint of Ferrari Daytona – and engineering from Spen King, with assistance from General motors, the 3500 was big, bold, and brassy. Yes, you could get 2.6, 2.3 and 2-litre models, and even a diesel (courtesy of Italian engine maker VM Motori), but it was the V8 powered fi ve-door fl yer that took the limelight. The story goes that a Rover engineer was loose in the General Motors plant in the USA one day when he fell over a V8 engine looking neglected on the fl oor. Further enquiries revealed it was a light alloy Buick motor that no longer fi gured in The General’s grand plan. A deal was struck, and soon afterwards the 130bhp, 3.5-litre, power unit found itself sitting snugly under the bonnet of the very last of the ‘Auntie’ cars, the P5 saloon. After that came the P6 3500, the Range Rover, Triumph TR7 V8 (briefl y), and – of course – the SD1.

The fi rst product from a newly created Rover, Triumph, Leyland, styling department, the SD1 looked very different, but under the skin it was a bit boring, with live rear axle (the P6 had a De Dion rear), and even drum brakes at the rear. But, toothy ‘though it was, the engine made up for the rest of the mechanics. A mid-term facelift (1982) brought us fi rst the uprated S model, then the 190bhp Vitesse. Drivers with string-back gloves took to the 130mph SD1, as did Plod, who found the combination of four-door roominess and power made it an ideal jam sandwich. It is said that when Rover production ended police forces around the UK went around buying up cars to feed into their fl eets over the following years. Also, with around 300bhp possible the potential of the car was not lost on the motorsport brigade. But, the SD1 had a major fl aw – it was a manufacturing disaster. Strikes, poor qualitycontrol, and what seemed to be built-in unreliability conspired to blacken its name. Still, when it was going it was a stormer – as Tom Walkinshaw, Tony Pond, and other hot-shoes demonstrated.

Get One Now

Even a stock vitesse is fast enough for many drivers!

Yes you can still buy SD1s, with the 190bhp fuel injected Vitesse the most sought after. As always, there’s rust to consider as your biggest enemy, but that nicely packaged power unit is very reliable, and extremely tuneable. We’ve seen cars as low as £500, with Vitesse models in the £2k-£5k bracket, although any restoration project is likely to be a drain on anyone’s bank balance. Go for a manual car if you can for simplicity’s sake.

Hotting One Up

The engine that Rover inherited from Buick was already old when it arrived on UK shores. Earliest versions had rope oil seals on the crankshaft and mains bearing caps that were apt to ‘fl oat’ and knock out the bearings. Rover’s development of the engine was somewhat reluctant, but by 1982 most of the major problems had been ironed out – including neoprene oil seals and a stiffer alloy block with cross-bolted mains caps. ‘Stiff’ blocks can be identifi ed by wider and more uniform strengthening webs in the centre of the Vee between the cylinder banks, and the cross-bolted type by the bolt heads low down along the sides of the block. The only other issue is in the retention of the cylinder heads. Buick engines had 18 retaining bolts for each head, whereas on SD1 motors one outer row of four bolts is not used and this creates uneven stress on one side. This does not necessarily cause the head gasket to blow, but allows unspent petrol and exhaust fumes to ‘weep’ into the centre of the Vee and contaminate engine oil, resulting in bore wear and cam and crank bearing failures. Unfortunately Rover did not fi nally solve the problem 1994, when the other row of four bolts was deleted and the heads were attached to the block by just 10 equally spaced bolts. A ‘fi x’ for 14-bolt heads is to torque down the centre two rows of fi ve and simply leave the outer four fi tted but un-tensioned and Loctited in place. Post SD1, Rover also developed the engine by increasing capacity. The original 3528cc engine has 89.5mm bore and 71mm crank throw, with the later 3.9 litre unit achieved by using 94mm bore. When the engine went to 4.2 litre, the crank was changed to one with a 77mm throw and the 4.6 litre unit is obtained by further stroking to 82mm. The 94mm bore is as large as the can be safely obtained within the block, and some of these engines have been known to crack behind the cylinder liners. Whilst upping capacity is sure way to up power, there’s plenty of scope for modifi cation of the cylinder heads. Careful attention to the shape of both inlet and exhaust ports and matching to the appropriate manifolds is worthwhile, as is cleaning out the shallow dish-shaped combustion chambers. Valve guide bosses can also be shor tened and smoothed to improve gas flow, and valve throats opened out. Standard 39.9mm inlet and 34.3mm exhaust valves are fi ne for road tune engines, whilst 41.4mm inlet and 35.5mm exhaust are about as far as you can go. A 9.75:1 compression ratio is best for most purposes; with so little chamber in the cylinder head, this usually obtained by the correct combination of pistons and the type of gasket used, either tin or much thicker composite type. With valve seat inserts used in the alloy heads, damage due to the use of unleaded fuel is not a problem.

A cam change should be pretty early on the list of modifi cations as the engine benefi ts from better breathing. If you stay on hydraulic tappets (there’s not much point in swapping to solid lifters on a road engine) the engine is limited to just over 6,000 rpm and so tuning for good mid-range torque is the best way to go. The timing gear and chain on early engines is likely to wear and warrants fi tting a Duplex set-up, although this is not practical on post 1994 engines. Hand in hand with any cam change must come an overhaul of the ignition system. Most original distributors are likely to be well worn by now and so (as far as tuner RPi is concerned) the only way to go on an early (pre GEMS management system) engine is to fi t a Mallory distributor. This operates as a 6-volt system (retaining 12 volt for starting) and so needs its own coil and ballast resistor.

Early SD1 engines were fitted with either SU or Zenith-Stromberg carburettors, and with these new needles and some fi ne tuning can accommodate mild stages of tune, but the fi rst fuel injection systems (Lucas L-Jetronic) are fairly crude on the electronic front and are not responsive to chipping. The Lucas GEMS management system used from 1994 onwards can be fully programmed, just as long as you use someone with decent experience. The best course of action for anyone with a pre-GEMS engine looking for a decent increase in power is to fit a fourbarrel Weber carburettor conversion, which sits neatly in the centre of the Vee. RPi’s Weber kit mates the carburettor to an Offenhauser inlet manifold. The carb is actually a pair of dual progressive chokes all contained in the same housing. On light throttle openings you get two (smaller) chokes supplying the fuel/ air mixture, then when you fl oor it the other two (larger) chokes come into play. Other carburettor installations have been tried with the engine - notably BL fi tted both Pierburg fuel injection and four Weber DCOE carbs on the rally TR8’s – but for a good power hike, increased response, and simplicity of installation at reasonable cost, the four barrel Weber can’t be beat. As with almost any engine, it’s essential to match the head ports to the manifold pipes. A 4 into 1 system for each cylinder bank with either single or bespoke, so the exact design of system has to be left to a fabricator.

So, what will you get for your money? A pair of modifi ed heads, fast road camshaft, four barrel Weber carb and some decent extractor exhaust ‘headers’ will see the basic 3.5-litre engine move up to somewhere around the 200bhp mark, whilst an associated capacity increase to 3.9 litres will move this to around 250bhp. Race engines, I period, maxed at around the 300bhp mark. Handling and brakes are straightforward to uprate – a general stiffening up with springs and dampers will suffi ce for most drivers – and a well sorted SD1 makes a fast road car, rather akin to a four-door Aston Martin!

How Did It Drive?

It’s big car, but with a big heart. The V8 engine is smooth and has oodles of torque to pull the weighty machine along at quite a rapid rate, although there’s quite a lot of body roll to deal with and the steering can be edgy. Most of the V8’s us press guys got our hands on were automatics, which for cruising is an ideal combination, but I also remember driving the six-cylinder Rover 2600, which was pretty gutless – fortunately no one ever gave me a 2300 or 2000 to test. Sadly, my everlasting memories of the SD1 include counting the number of dead ones on the M1 hard shoulder!



User Comments

This review has 1 comments

  • The article is flawed with misinformation, unfortunately many folk read this kind of stuff and believe it.

    If the writer of this article was to do their homework and comeback and take down their wobbly article the world would be a better place.

    And for the record the Walkinshaw Rovers with EFI made over 300 HP at the rear wheels and their best ever Camshafts were made in the UK and were nothing like a US made Crane.

    The Rover SD1 V/8 had more head studs then the Buick fact of life.

    Rover made the engine a good engine, in the first instance Rover cast the engine in the same Alloy as used by Rolls Royce not the US junk alloy.

    The adjustable rocker arms used by Walkinshaw were made by Volvo, no American parts were used in the Rover SD1 engine.

    Shame that the article is so flawed.

    Comment by: Terry Handley     Posted on: 22 Dec 2011 at 02:04 PM

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