Concours Sportscar Restoration

MECHANICAL SERVICE

We provide meticulous servicing and repairs to all Jaguar and Aston Martin models at competitive rates. Specialising in only two makes enables us to stock all service related components including brake parts, suspension parts, tyres, etc to reduce the amount of time that you are without your vehicle. Our extensive knowledge and experience in Jaguar and Aston Martin vehicles, enables us to pick up potential problems before they actually become problems - preventive maintenance. This ensures that Jaguar and Aston Martin ownership is as pleasurable as it is supposed to be.

Fuel System Servicing

In conjunction with your next tune up, insist on giving your vehicle's fuel system a much needed clean and service.

This state of the art process cleans the fuel injectors, fuel rail, fuel damper, fuel pressure regulator, fuel pipes and hoses and fuel cooler. It dissolves carbon deposits from inlet valves, piston tops, combustion chambers, exhaust valves and exhaust manifolds.

The process will improve fuel consumption, reduce emissions, improve throttle response and will restore engine power.

During the cleaning process the fuel pressure and flow rate will be observed and recorded. Fuel pressure regulators and injectors will be tested for leakage and reported. Before and after inlet manifold vacuum readings will be recorded indicating the improvement in engine efficiency following the cleaning process.

For a technician to check all these conditions would take considerable time and specialised equipment but our machine does all this automatically providing instant diagnosis of problems that would not normally be found during a "tune up".

This cleaning process is far more than just an injector clean.

You will feel the improvement in performance and will notice a decrease in fuel consumption even if your car has no fuel system problems.

It is recommended that this fuel system cleaning process be performed in conjunction with a conventional tune up every 40,000 kms to maintain peak fuel system efficiency.

Dyno Tuning

Most racing car owners know the benefits of tuning and developing their racing car engine on a dynamometer (or dyno for short), but a growing number of owners of standard road cars are wisely having their car dyno tuned. And the results and benefits are, more often than not, simply amazing!

Gone are the days of customers having the hell revved out of their car on a dyno with the exhaust glowing red and the engine about to melt into a smouldering heap on the ground while some mechanic rotates the distributor to get the most power on the dynos' horsepower dial.

Unfortunately this is the perception most people have of the whole dyno procedure and unfortunately there are mechanical workshops around who still operate the old style dynos in this manner.

These days the modern chassis dyno is controlled by a PC which monitors a whole host of engine and vehicle conditions and allows the operator to perform a "run" in as little as 5 seconds. That is the engine is operated at full throttle under load from around 1500 rpm to the desired cut off point, usually about 5000 rpm on a Jaguar, while the computer is monitoring the air fuel ratio and is plotting a power and torque curve on the screen.

An engine that has not been run and adjusted on a dyno is simply not running at peak efficiency and is not producing its best horsepower or torque.

That is a big statement, but I have dynoed almost every model Jaguar (and lots of them) and we have always made an improvement in either fuel economy or performance and usually both. And usually they are big improvements.

By utilising different features of the dyno, numerous engine conditions can be observed and faults easily identified such as incorrectly balanced carburettors, faulty fuel pressure regulators, worn or broken distributor mechanical advance springs, incorrect camshaft timing, dirty injectors and obviously a tired engine.

From the initial run the first step is to ensure that the engine is not running lean or pinging, both of which are unsafe engine conditions. If the engine is running lean, a richer set of carburettor needles must be fitted or the computer or fuel pressure adjusted on a fuel injected car before another run is completed. If the engine is pinging, the timing must be immediately retarded.

If there are any suspicions about the condition of the engine, compression and leakage tests are performed. At this stage the spark plugs, points, air and fuel filters are replaced and the timing set at manufacturers specification for a starting point.

From the second run on, small adjustments to the mixture or the timing are performed one at a time with the mixture, power and torque compared to each previous run. The aim is to achieve as close to perfect a mixture as possible with the timing set to achieve the most power and torque throughout the entire rev ranges. The engine is then in a perfect state of tune.

For some cars this just means a simple tweak on the mixture screw and a couple of clicks on the timing vernier, but other cars can be more challenging requiring different needles and the distributor advance curve modified. Choosing the correct components to fit is where the expertise of the operator is called on and he must have an extensive range of carburettor needles and advance springs at his disposal.

For performance tuning he must also have a range of different length ram tubes, different air filters, fuel pressure guages and regulators and a range of Weber jets, air bleeds, etc.

We have found that with most cars the mixture is not correct throughout the entire range and the timing is never correct, even on engines that are fitted with the Jaguar specified needles and that are set to Jaguar's specified timing setting.

This is because throughout the life of the car, the engine has probably been rebuilt incorporating an overbore, different pistons, the head skimmed, valves replaced (or enlarged). The exhaust or mufflers may have been replaced, the air filter may be different and the car is definitely running on different quality fuel to when the manufacturer derived their tuning specifications.

Also, most manufacturers arrived at these specifications on an engine dyno. The major advantage of a chassis dyno over an engine dyno is that the engine is being tuned in the environment that the engine operates in. The intake air temperature is the same, the under bonnet temperature is the same and the car is utilising the full exhaust unlike an engine dyno where the engine is sitting in a room breathing room temperature air with no mufflers.

Any engine that has been modified in any way from, for example, simple sports air filters or non standard mufflers to bigger valves, different carburettors, electronic ignition or different camshafts, it is absolutely essential that the car be checked on the dyno.

So don't think that just because your car is fitted with the specified needles and the timing is set at the specified number of degrees that it is tuned ... it almost certainly isn't. And the only way to know is to have the engine tuned on a dyno.

We have access to a chasis dyno and this equipment combined with our experience in high performance engine development has enabled us to produce 6 cylinder Jaguar engines with over 250bhp at the wheels!

The following are three examples of printouts from dyno tuning sessions:

This graph shows before and after horsepower and torque curves from a standard XJS HE that came in for a tune. The car was idling fine but was using excessive fuel and ran quite rough above 4000rpm. This is how the majority of injected V12's are. Owners tend to accept bad fuel consumption and these engines rarely see above 3500rpm. After replacing spark plugs, filters and correctly setting the throttle shafts, the timing was adjusted on the dyno to achieve an incredible improvement.

This is a graph from a 4.2 engined MKII which we have developed as a road registered car that sees regular club track events. Has anyone done better than this with 10.5:1, SU carburettors and unleaded fuel ?

This final graph shows the kind of rear wheel torque and horsepower improvements that are achieved with 3 of our performance enhancing kits. An otherwise stock 1986 XJSHE was dyno tuned to achieve the best results possible, then we fitted our 5 speed Supra gearbox kit with aluminium flywheel, a 3.54 ratio differential and our large air boxes, K&N air filter elements and adjustable fuel pressure regulator and returned the car to the dyno. "A completely different car" was the owners response. We made the XJS a true sportscar to be enjoyed.

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