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Hillman Imp

Do you drive this great classic or are thinking of buying one? Here’s how to ensure that you get the best out of your car for ye Published: 22nd Sep 2014 - 0 Comments - Be the first, contribute now!

Hillman Imp
Hillman Imp
Hillman Imp
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Launched in May 1963 as an all-new design, from an all-new factory at Linwood in Scotland, the Imp was inspired by the rear-engined Chevrolet Corvair and its designers hoped it would bring a touch of class and sophistication to the UK’s small car market, inspired by the success of the rear-engined VW Beetle, Sadly, the Imp lacked Volkswagen’s build quality and reliability, although today an Imp can be as reliable as a Beetle or Mini, and here’s how to get the best from yours.

1 BRAKES

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Imps used drum all round, even Sports, which were fine at the time, and for many just a set of harder linings along with a servo will be satisfactory. However, on today’s roads or with a tuned car you may want to upgrade to discs at the front and you can modify disc brakes from a Ford Fiesta or Vauxhall Viva.

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If yours hasn’t been used for a while, there’s a chance the brake cylinders have seized and the rear ones are particularly prone to this. A good strip-down and clean, together with new linings, could make a big difference without the need for discs. Fronts similar to Escort and specialists such as Demon Tweeks should be able to supply the components you need.

2 SUSPENSION

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Uprated springs and dampers make a big difference, as can correcting the positive camber and higher ride height of pre-1967 cars. Hillman Husky came with uprated rear as standard, along with stronger wishbones and trailing arms, so fitting this set up to a standard Imp can improve the handling. After 1967 Imps changed to a lower pivot suspension system.

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You can change the springs and dampers to the works ‘Monte Carlo’ rally settings. To do this, change to shorter Spax or Koni dampers and adjust camber of the front wheels to give up to another one degree of negative – do this by modifying king pin carrier. A front anti-roll bar off an early Renault 5 can be made to fit quite easily. It’s also worth fitting poly bushes to improve handling if the original bushes are tired.

3 ELECTRICS

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It’s worth thinking about an upgraded ignition system of some degree. You can buy upgraded ompetition distributors and, for these, check out Imp engine specialist such as Reg Pattern Engines (www. hillmanimpspecialists. com). At the same time, you should also fit a sports coil and performance ignition leads for max effect.

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One of the best upgrades is to fit a simple electronic ignition like a Lucas 25D Powerspark which runs on the car’s standard positive earth set up. Costing £45 (from http://www.simonbbc.com). Apart from the rarity of pre-1968 switchgear, Imp electrics are generally pretty robust but you may find an uprated dynamo useful along with a larger, heavy duty battery.

4 ENGINE TOP END

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Twin or twin choke carbs with an improved exhaust manifold (try Janspeed) on a polished head add another five or so bhp. Next stage are larger inlet valves. Sport cam spec is the minimum. Tuners include Corley Conversions, www. theimpclub.co.uk. Or you could fit an alien engine. The Imp’s layout lends itself to another powerplant. Vauxhall and Ford 16v engines are two such conversions that are feasible with some ingenuity.

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Water pumps tend to wear out and oil leaks are normal. Key for a happy Imp is to maintain the right mix of anti-freeze. Any form of overheating – which can include air locks as it’s hard unit to ‘bleed’ will usually take the head gasket. Undue pinking under load suggests the head has been skimmed one time too many, although they do feature a very high compression ratio. Commer Imp van used detuned engine with lower compression ratio head.

5 ENGINE BOTTOM END

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Most common route is to go for the 998cc and wet liner unit but supply long dried up. However, specialists like Transimp (transimp.co.uk) will bore out an original with wet liners for either 930cc or 998cc. Then a head from a Sport or Mk2 Imp is normally used, since these have an oil drain on the back. The front mounted 930 unit found in the Sunbeam is not a direct fit unless the crankshaft is modified but it can be done, says Transimp.

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Parts supply is fair. Bottom of the engine is normally okay, until power exceeds 80bhp, when it may be worth fitting a tougher crank. It’s important not to use split-link timing chains. Corrosion of unit leads to clogged waterways and engines soon developed a reputation for overheating. Mk1 blocks weren’t as durable as straight-edged Mk2. Always flush block with a descaling agent periodically to prevent sludging.

6 COOLING

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If you want to maximise cooling efficiency, there are specialists who, on an exchange basis,  supply you with a radiator fitted with higher efficiency cooling elements and it’s a good move even on standard engines, along with an electric cooling fan. It would be worth upgrading the hoses and replacing the water pump at the same time.

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Imp gained a reputation for overheating, usually because of the wrong type of coolant used without a corrosion inhibitor which causes the aluminium to corrode and then block up the waterways. The radiator is best removed for flushing – including the fins. Patience is needed for bleeding an Imp’s system – speak to an Imp specialist for advice.

7 TRIM

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A popular mod was simply to take the trim from a scrapped version of one of the more upmarket models, such as the Singer Chamois which had a wood-finish dash with more upmarket instruments. The Sport models also had upgraded interiors while later version used a better dash layout. Other than that you can opt for leather trimmed seats and new carpet sets.

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Specialists can help with trim and the Imp Club has a good list of contacts although some parts are becoming scarce. For instance, Coverdale Carpets in Wigan has stock of high quality carpet sets (http://www.carcarpets. co.uk). East Kent Trim Supplies has a large selection of rubber and cloth trim (http://www.classiccar-trim.com). Later post 1968 Imps used very simple door boards that are easy to replicate.

8 TRANSMISSION

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Jack Knight Developments in Surrey, marketed a conversion for third and fourth gears using straight-cut gears which were used for racing. Jack Knight Developments is still going today and can supply components for the Imp – http://www.jackknight.co.uk. Imp van used lower final drive unit so better for acceleration.

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An obstructive change is usually duff linkages costing a tenner to rectify. Another common problem is failure of the rubber donuts that make up the Rotoflex drive couplings,. These can be bought for as little as £30 off Ebay, but you’ll need to spend more if you have to rebuild the entire drive shaft set-up.

9 BODY

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If you’re going for the rally look with your Imp, then you can still get glassfibre panels to create wider flared wheelarches, or even to add a front spoiler. Contact specialists such as Malcolm Anderson (www. malcolmanderson.co.uk) to see some of the panels that are available, including steel repair panels. An important contact for spares and advice is also the Hillman Imp Club, which has a comprehensive list of spares (http://www.theimpclub.co.uk).

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Like its main competitor, the Mini, the Imp suffers badly from corrosion but perhaps not so dire? Typical areas to check are the sills, wheel arches, floor pan and even the edge of the front bonnet. You can get bodywork repair panels from specialists such as Malcolm Anderson, with wheelarch repair panels costing from £80. Other areas to rust include the rear lower corners, but repair panels for this are available costing about £70 each.

AND ANOTHER THING…

Like the Imp’s mechanical set-up, but want something that looks even more unusual on today’s roads, plus feels a bit more sporting? Well, why not opt for one of the kit car specials that were offered over the years for Imp mechanicals. Famously, the Ginetta G15 was one of the best handling kit cars of its day, with its rear-engined Imp power. Others include the Davrian and Clan Crusader, also rear-engined Imp-based two-seater sportsters. They can be tuned-up just like a standard car, plus their lightweight GRP bodywork means that they are faster, even with a fairly basic engine fitted – think of a road- legal go-kart!



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