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Tuning & modifying classic cars.

Hillman Hunter rally car
Cars have been modified and uprated ever since man first hit the gas pedal, scattering horse-drawn carriages in their wake. Purists will throw up their hands in horror at the mere thought of modifying or uprating an oldie, to make it more suitable for the daily drive, or for competition. I'd be the first to agree that it should be a criminal act to wilfully chop about & butcher an original condition classic especially when it's mega rare. I winced only the other day when I spotted online a photo of a hot-rodded Austin Dorset (the 2dr Devon effectively), sacrilege!
At the one end you have custom cars. Custom cars usually generate much frothing of the mouth in most classic car circles. I'm in two minds about this. If a rare car has been cut about then I think it is a great shame, and something that should be avoided wherever possible - sadly though, cars often only fall into the hands of customisers due to neglect or indifference from mainstream classic owners, the self same people who then decry a customiser's alterations afterwards. So long as the car is not too rare, and there are plenty of original examples around, I don't have much of a problem with most custom jobs, although there's no getting away from the fact that it is depleting an already low stock of potential original cars to restore correctly. Many rare or significant vehicles get irreversibly modified all over the world, with many rare vehicles (often light commercials in the case of the USA) being retro-rodded with modern interiors, and sat on modern chassis & running gear. One inescapable fact though is many properly completed customised cars are often finished to a far higher standard than many classics seen lurching around, limping between MOTs etc on a wing and a prayer (much as it pains me to admit it!). But customising is the extreme end of the scale, and one that doesn't really sit too well with me (though people can do what they like with their own cars after all - only classic car banger racing really upsets my stomach).
More acceptable to most (bar the purist) are changes in keeping with the car, perhaps to a later specification of the same engine, fitting of better brakes from later models, and so on, and a few of my old cars have been treated like this.
There is a huge industry dedicated to the uprating of older car engines, and is so vast that I can only really mention it here in passing. From the earliest days, people have been looking for ways to improve their engine's efficiency or, more usually, give it some more beans in the oooomppphhhh department. Any number of companies have come & gone, offering tuning mods for both basic and exotic machinery. Finding proper period tuning gear for classics is a boom area, and well known performance equipment is keenly sought by both fast road, and racer, driver alike. Certain names have become holy grails when talking tuning accessories, just mention Aquaplane, Buckler or Ballamy to a Ford sidevalve club racer and he/she will go all gooey eyed and weak kneed. Similar tuning gear was available from legendary suppliers such as Speedwell, Raymond Mays, Ruddspeed, to name just a few suppliers (see more about the suppliers of tuning parts in the 1950s/1960s here). Some manufacturers even produced and marketed their own ranges of bolt on goodies, such as Leyland with their Special Tuning outlet. Of course there was plenty of opportunity to modify and tune your existing oily bits, just needing a set of tools, a decent tuning book, and a little mechanical dexterity to do the business. Head skimming, port polishing, and trick manifolds & exhausts have long been the staple diet of any boy racer, either now or decades back, and what was done then is equally done now by current owners of historic cars, often for competition purposes.
Volvos for example (see below) are well served on the uprating front, I'm thinking here of the Amazon 120 range of which I've had a few. Early cars can be fitted with later engines that virtually go straight in, offering more power and better spares support. Twin carbs off later models also replace weedy single carbs, and a variety of cams are available depending on your mood.
Modified MG, Volvo and Porsche
Hand in hand with engine mods should (!) be updates to the braking system. Early Heralds for instance can be upgraded to Spitfire or GT6 disc brakes, and different compounds of disc pad can be chosen depending on the usage. Servos are also a popular retro-fitment, once again Volvos for instance being a classic case where grubby bits from a later example can be plumbed onto an earlier example of the same model without too many headaches, making the brakes easier to use (although not giving any extra braking power as such). As with all mods, care needs to be taken with all modifications so I strongly suggest that enquiries are made with relevant clubs and specialists to establish what can and cannot be done - don't just assume it'll work ok in an emergency!
Suspension is often criticised on older cars, and often fails to deliver the goods when it's been neglected, or subjected to increased strain due to engine mods and so on. Cars with telescopic dampers can usually be updated quite easily, although go with too stiff a setting and watch your fillings disintegrate as you hit a rut in the road. If however road comfort is not high on your list of requirements, you can often fit uprated rubber or solid suspension bushes, making the steering and handling altogether more direct, at the expense of road noise and comfort. Wheels and tyres are often changed whenever suspension mods are considered - simply fitting radial as opposed to crossply tyres can transform the grip of an old motor, though beware the extra forces that the better grip generated by radial tyres brings will load up the suspension more than it was designed for, and its not unusual for standard road wheels to fracture across the stud holes, not being designed for the loads now being passed through them. This is just one example of where tuning and uprating changes are best considered for the whole car at once, and not just one part of the car at a time. Wider wheels and tyres can help roadholding enormously, but remember to check the offset of the wheels even if they match your existing stud pattern, and watch out for the wheel rim or tyre fouling at extremes of steering lock, or rubbing against the wheel arch when the suspension is in compression. Wider rims can also cause loading issues as already mentioned with ref to the cars suspension and other bits of undercarriage.
One car I owned a few years back had been significantly modified, but across the whole and not just in one area. The car as bought was effectively a Mk3 Spitfire, sat on an uprated GT6 Mk2 (hence rotoflex) chassis, with a 2.5 straight six taken from a Triumph saloon of the 1970s. The car was unfinished when I bought it, but all the essentials were in place and the series of updates had been carefully thought out. The suspension had been uprated from the normal Spitfire arrangement, and wider wheels had been fitted. The engine was mounted 1' further back in the chassis, to improve weight distribution. They could have just dropped it on the normal engine mounts, but this would have made the car very front heavy. As it was it handled like a charm, but moving the engine back had meant that extra work was required to make it all work - the chassis rails were reprofiled, the propshaft shortened and balanced, the gear lever extension cut down, the bulkhead reprofiled, throttle linkages custom made, and a homemade exhaust manifold was built. I bought the car half finished, and ended up fitting a replacement wiring loom, getting new floors fitted, fitted a new oil cooler, and got the thing so that it actually ran and was MOTable. These modifications could not be undone due to the structural work that had taken place on the car, but there are plenty of original cars about and anyway, the changes had been made before I bought it. Everything had been done using parts that were available when the car was new, and where possible sourced from other Triumph models.
Owners clubs can be a great source of information when it comes to modifying cars. Many tuning jobs have been done time and time before by others (eg Fiat Twin Cam engines into Morris Minors), so there is often a great well of information that can be tapped into, and the internet also opens up huge opportunities to learn tricks of the trade from those who've been there already.
To sum up, tuning & modification is all about how far you want to take the modifications, what you plan to use the car for, and equally how large your wallet is. You'll need to advise your insurance of any mods too. Oh, and many will request you get an engineers report done to assess the quality of your conversion work. Good luck!
Modified 2500cc Spitfire Mk3

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