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Triumph Spitfire

Published: 15th Jan 2016 - 0 Comments - Be the first, contribute now!

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Codenamed ‘Project Bomb’ – here’s how to make your Spitfire go like one!

The Battle of Britain was raged on our roads back in the 1960s and 70s – between Spitfire and ‘Spridget’ drivers. So Whose side are you now on?

Critics of the Triumph said that the Herald-based sports car was too soft and cissy compared to the harder core Austin-Healey Sprite and its MG Midget clone, but let’s not forget the success the Spitfire enjoyed in both race and rallying, even competing at the Le Mans 24 Hours.

You may not want to go that far with your cherished classic but there’s a lot you can do to make your Spitfire swifter and safer on the road and ideal for light motorsport use. Read how!

BEFORE YOU START

First things first, before making a high flyer you need to ensure that your car is solid. The chassis is prone to rust but the good news is that you can weld in sections or even buy new frames and riggers if you so wish.

Mechanically, you can’t get a simpler sports car. That E-type like forwardhinging bonnet allows superb access to the engine and front end and spare parts availability is excellent.

The main concern is that old Triumph foible of crank thrust washers and these need to be okay before you tune the engine. When overhauling the engine you should replace originals using the latest aftermarket types.

HOTTING ONE UP

The engine first started out as a ‘Standard’ unit of just 803cc and ended up almost double the capacity! Of 1147cc ‘1200’, 1296cc ‘1300’ unit and 1493cc ‘1500’, apart from the 1500 they all share the same 76mm crankshaft throw although you can’t bore the engines out to their next respective sizes without a bit of hassle.

However, you can overbore a 1296cc unit by 40 thou to give 1387cc and some have even stretched it to 1584cc. The 1500 is pretty much at the limit although it can be rebored by as much as 60 thou to a 1604cc capacity by using TR6 pistons. However, seek expert advice first as this modification demands custom con rods and bore liners imported from the USA and they don’t come cheap!

Also some engines (made up to 1965) featured weaker con rods and are not suited for dramatic tuning. One of the reasons why specialists hark on about the 1296cc unit, apart from its larger size, is the far more efficient eight port cylinder head employed. Sadly, this can’t be fitted to the smaller units as the stud pattern is different.

One peculiarity is that the 1200 head features smaller valves than the Herald! Camshaft changes can be achieved with the engine in situ as it can be pulled out at the front once the grille radiator and head are removed. On the earliest Spitfires the tubular extractor manifold fitted to the Mk2, is worth fitting if you can find one.

Moss sells TriumphTune and Piper cams catering for road, fast road and Race for around £180 incidentally, as well as a range of cylinder heads costing in the region of £900 as do some specialists like Moordale. The 1300 engine is regarded by most as the best unit to gain meaningful bhp from and this mod alone in an earlier car will give a useful power gain.

If you don’t mind a less rev happy but lustier engine, then the 1500 is a good option and not as bad as many claim it to be, so says Triumph experts Moordale Motors in Potters Bar, Hertfordshire (01707 650284). “A lot of rubbish has been spoken about these engines,” says Dale and particularly likes the welcome torque of the larger unit. It can rev almost as high as the 1296cc once the bottom end is carefully balanced and the flywheel lightened by around 5-7lb, he adds.

The 1500 unit had the advantage of only a little more power over a 1300 and has problems wearing out its big end shells. Moss advises using uprated engine fasteners for more accurate control of clamping pressure and reduces the risk of failure during use and is recommended for uprated or competition engines.

With a fully modded cylinder head, racier camshaft and a single weber DCOE carburettor (you can’t use twins due to the earlier Siamesed inlet ported head) you can muster up to 90bhp or more from a 1200 Spitfire.

The larger 1300 unit yielded up to 130bhp as a racer in its heyday but in this state will be a pig for road driving; it’s best to go for a milder tune but you’re still looking at over 100bhp on Weber DCOEs or 80-90bhp if keeping with the standard 1.25in twin SU carbs. Larger twin 1.5in Strombergs found on the Vitesse, GT6 and 2000 saloons are a useful upgrade but speak to a Triumph tuner beforehand as some advocate 1.5in SUs instead which fit much more easily and give much greater needle selection for finer tuning.

Cooling, particularly on the 1500 can be marginal and do with an upgrade by dint of a superior radiator or core (try Radtec or Express Radiator Services). Experts have improved oil flow to the centre main by opening up to 5/16in and although some say you don’t need an oil cooler it is of most benefit on a highly tuned 1500.

You can’t ignore the fact that you can turn a Spitfire4 into a Spitfire6 by slotting in the six pot and it transforms the Spitfire’s pace and character. It’s not a simple drop in and you’ll need to alter and beef up the chassis; some reckon dropping a Spitfire body on a GT6 frame is the best solution.

You will also need a GT6 bonnet with its necessary power bulge although we gather that by shifting the engine rearwards and modifying the original engine plate you can retain the lower Spitfire frontal. You need the 2000 gearbox, which means further mods to accommodate the clutch slave cylinder.

An easier swap is the slant four Dolomite engine which is almost a straight drop in, presumably because Triumph once had plans to do this although both swaps are only really justified if you intend to tune the engine’s further; the standard TR7 engine kicks out about the same as an easily tune 1300 can achieve plus the smaller lighter engine aids handling balance.

There’s plenty of personal advice on respective websites and forums while it’s said that Canley Classics still owns the original development car. A Hot Car mag reader sent details of such a swap way back in 1975 so it can be done at home!

HANDLING THE POWER

Before trying to keep this high flyer’s feet (or rather tyres) firmly on the ground, let’s tackle the transmissions first. The optional overdrive allows six-speeds in theory and as a result gives you the choice of either benefiting from improved cruising with taller gearing or, if you drop the ratio in the axle, better performance but without the engine screaming its modified head off.

The overdrive works acceptably well and can be uprated with stronger clutches and springs and higher operating pressure for more ‘immediate’ engagement. O/D Spares of Rugby (01788 540666 http://www.odspares. com) charges around £80 to uprate your existing unit on top of its usual overhauling prices. On single-rail boxes, it’s worth fitting the later Spitfire gear lever so the overdrive switch is atop and so you can change gear and flick in and out of o/d in a single action.

Moordale says that when this O/D Spares uprated ‘Race’ unit is wired up properly you effectively have an eight speed gearbox that is brilliant for competitions such as Autosolos/Autotests and if you tackle rallies with lots of hairpin bends.

You can fit the evergreen Ford Sierra Type 9 five-speed gearbox but this may be unnecessary as well as expensive.

One trait that has always blighted the Spitfire is its tricky handling caused by the quirky rear transverse leaf spring, famous for its ability to ‘tuck in’ the rear wheels just when you need them most!

Various aftermarket tweaks were devised over the decades, serving not only the Spitfire but also Heralds, GT6s and Vitesses ranging from a simple ‘camb compensator’ costing a few quid back then to a virtual adjustable full-race rear end (from leading tuners SAH).

When the Mk4 Spitfire was launched, Triumph finally got around to sorting it out properly and the factory revision is generally regarded as the best modification. Budget on around £150 from specialists for a similar set-up, which when allied to 175/65 section tyres (about the widest you need for road use) makes the once skittish Spitfire handle very well. If you want to retain wire wheels then your tyre choice and size is more limited. Be careful that the rims don’t rub against the front flexible brake hoses.

There’s a choice of dampers and springs to mull over along with better (thicker) anti roll bars though these MUST be matched to any rear end improvements; speak to a specialist first for best advice on this and where best to fit harder polyurethane bushes. We say this because Spitfires aren’t the most easiest of riders even in standard trim and any uprating will only make the ride even harsher; a good reason to fit adjustable dampers so you can adjust to suit your mood.


Brakes? All boasted front disc brakes, and as long as they are in good order should cope with mild performance tuning, after slipping in a set of EBC Green Stuff or Mintex 1144 pads. Think twice about fitting the larger GT6/Vitesse anchors as they need the appropriate master and slave cylinders to make the switch perform properly, which is often overlooked, not to mention front suspension vertical links.



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