Practical Edge – Skills Training

Category: Classic cars

Articles about classic cars, bikes and trucks.

  • The future of the past

    Our entire way of life IS going to change. For many of us life is already very different to how it was just a couple of years ago.

    The Anti-Car movement is gaining ground, and with some good reasons such as road deaths, pollution, congestion, noise etc. Climate change is also changing the public mood rapidly and governments are realising that action is needed, and when governments take action the results are often unpredictable.

    Make no mistake; the car and private car ownership is about to get a whole lot more contentious and problematic.

    Classic cars, bikes and trucks are wonderful things, they bring great joy to many people, not just the owner. They also help support a vibrant industry with amazing specialists and incredible skills. There is a bigger picture.

    We all know that classic cars are a very small contributor to climate change, low annual mileages and simple maintenance are crucial points. But even though it’s a small part of the problem, it is still part of the problem and so a very easy target.

    We can, of course, become part of the solution. Making physical changes to our vehicles to avoid the environmental issues, moving to net zero fuels such as synthetic or even pure ethanol, not using our vehicles in congested areas, using vehicles to bring joy and supporting charity events for instance.

    But we have to act now, and we have to gently educate others to show the positives of classics.

    Yes, it means we will have to spend money and modify our classics. But the alternative, where we are seen as a public enemy and legislated out of existence, is not worth thinking about.

  • Classics

    Your Classic car is worth so much more than just money, it is a piece of our engineering heritage, a physical testimony to all the people who designed it, built it and maintained it for all those years. It’s living history.

    We have to value our engineering heritage more than we currently do, not just for perfectly valid nostalgic reasons but for the very practical point that lessons from the past are vital when solving problems of the future. So many times I’ve seen very bright young engineers designing solutions that have basic flaws due to their lack of experience and knowledge of previous ways of solving very similar problems.

    The is a huge wealth of knowledge in our classic vehicle community, methods of machining obscure parts, use of alternative materials, the skill gained from years of experience of being able to look at something and instantly knowing if it will work or not.

    For instance one of the very modern systems in engine management ECU’s uses the change in resistance of the mixture, measured at the spark plug, as it get compressed to indicate compression and hence control spark timing as appropriate, this technique is part of the ignition control on some variable compression ratio engines. This idea came about by observing how trembler ignition works on a Model T Ford.

    And that means we should all cherish our fantastic engineering heritage, and we should also do our best to enlighten those who so far have failed to appreciate it. Car shows are one of the many great places to do this, engaging with people who already appreciate the fantastic lines of a beautiful old vehicle or relish the atmosphere that our classic car community creates, they are already head down the road to enlightenment so let’s all do our bit to share the enthusiasm for great machines and the people who made them.

    If you don’t already know much about the engineering on your classic, which is fine, I’m not suggesting it is something for everyone, it can be fascinating to dig a little deeper and find out more. Look at what makes your car different to other models and ask why did they do that? The answers are often shrouded in myth but often fascinating, sometimes there was a great idea about making a performance or efficiency improvement by doing things in a different way, sometimes it’s down to the complexities of manufacture or simple cost savings. What ever the reason for unique features in your car there is always a story behind it.

    And whether that unique idea worked or failed there is always something very valuable to be learned from it. Some things change because there is a clear advantage to a new method, such as fuel injection or electronic ignition, but sometimes it’s not so clear why old methods died out, such as Trafficators.

  • Know your engines

    The engine- throbbing heart of the car, and it gives the car soul too. But how many of us really know anything about it?

    The basics of how your engine work are fairly simple, but modern engines have little details that would scramble the brains of Einstein. Luckily I will gloss over them and keep it simple!

    Basic principal.

    Mix fuel with air and set fire to it, it goes bang and expands damn fast. Now that’s fine for pyro effects in films but doesn’t push a car along. The engine converts the explosion energy into a twisting motion that can eventually drive the wheels using some fairly simple mechanics.

    It works by keeping the explosions in cylinders, usually about the size of beer cans. The top of the cylinder is sealed with the cylinder head which has valves in to let air in, and some more to let exhaust gas out. The other end of the cylinder has a piston in which is pushed down by the exploding gas.

    Now if that was all there was then the explosion would just launch the piston into the ground like a badly aimed cannon ball, so the piston is connected to some mechanical links, which as it turns out are exactly like the ones on a bicycle. No, really they are. When you pedal a bike, your legs move up and down, imagine your knee is the piston and your lower leg is the

    connecting rod (con rod) which moves the pedals which are on a simple crank, and that’s how up and down is turned in to round and round. Two pedals on a bike are like two cylinders of an engine, engines with more cylinders just use a longer crank with more pedals on.

    All that lot needs to be held in place by something pretty solid, this big lump of metal is called the engine block. Some engines separate this into two bits, the cylinders in a cylinder block and the crank in a crank case. The bottom end with the crank in is sealed off underneath with a glorified bucket called a sump, which catches all the oil running out of all the well lubricated rotating parts.

    Valves.

    Each cylinder needs a valve to let air in from the intake system, and another one to let the burnt gas out into the exhaust system. The valves are usually like the stem of a wine glass, or a penny on a stick if your not posh. The cylinder head has holes cast through it to let gas pass, called ports. The valves are stuffed into the ports so that the valve head blocks the port off at the cylinder end. Pushing the stick part of the valve down lifts the valve head off the valve seat in the cylinder head so that the gas can pass. It only lifts a few mm so the shape of the valve seat makes a big difference to how much flow there is, and so power. Its these little details that the really good tuners sort out.

    Stroke.

    The valves have to be opened and closed at just the right point in the cycle, a four stroke engine opens the intake valve so that as the piston moves down it drags air and fuel mix into the cylinder, that’s the first piston stroke. Then the intake valve is shut and the piston comes back up on the second stroke, squashing the mixture. If you compare the size of the mixture at the bottom of the stroke to how small it is at the top of the stroke you usually find that its been compressed by roughly ten times, this is the compression ratio. The compressed mixture is set fire to near the top of the stroke, which forces the piston back down on its third stroke which is the one stroke that makes any power and pushes the car along, all the other strokes actually use power. Then when that’s done the exhaust valve opens and the piston comes back up, the fourth stroke, pushing the exhaust gas out. Then it all starts again, at full chat it might repeat 100 times a second.

    Cams.

    So what makes the valves go up and down then? That’d be the cam shaft, its a long stick with lumps on, its located above the valves (usually) and spun round in sync with the crank and pistons so that the lumps hit the top of the valve stems and force them open at just the right moment. The valve then returns shut again because it has a very stiff valve spring pushing it shut, unless its a ‘Desmo’ engine, but that’s another storey for another time!

    The cam is designed to open and close the valves to give the right performance, its a complex subject but the design of the came lobe shape has a massive effect on how well the engine breaths and is one of the top tuning parts.

    There are loads of variations on this theme, most modern engines double up on valves and have two for intake and two for exhaust in each cylinder, just to get more gas flow and power. Many use two cam shafts (twin cam), one for all the inlet valves and another one for the exhaust valves.

    Cams don’t directly touch the valves, the follower reduces friction and can be either a steel disk, called a shim, which sits in a little bucket, or sometimes there is a little lever, called a rocker, and sometimes its a little hydraulic cylinder, called a tappet, which is pumped up with oil so that it automatically sets just the right valve clearance, which is crucial to getting good performance and reliability. This clearance has to be great enough that when the valve is shut it sits hard against its seat, otherwise there is a chance high pressure hot exhaust will be pushed through and burn the seat out. But if the clearance is to large then the valve won’t fully open and it will make a clattering sound as the lobe hits the follower with a thump, which can be damaging.

    The cams are driven by either a chain or a toothed belt that is driven by the crank, which has to go round twice for the pistons to do the four strokes, so the cams are driven at half the speed of the crank y having a drive pulley twice as big as the one on the crank .

    The cam and crank pulleys are usually linked by a belt or chain which is aligned so that the cam opens the valves at just the right moment, this is cam timing. If the valve opens too soon or too late then less gas is pumped through the engine and power drops, and if the timing is way out the valve might hit the piston at the top of the stroke and that means big engine damage. Adjustable Vernier pulleys are available to fine tune the timing on race engines.

    Oil

    To keep all the rotating parts moving freely, oil is pumped through little tunnels or galleries in the block and head which feed the crank, con rod, cams and valve stems. The oil pump is usually driven off either the crank or the cam and has a pressure regulator and an oil filter to ensure a steady and clean supply of oil. Using the right oil makes a difference to power and reliability.

    Stay cool.

    The explosions generate a hell of a lot of heat, in fact its enough to melt the engine. So coolant, usually an equal mix of glycol and water flows through hollow passages around the cylinders and cylinder head, especially round the valve seats, to let the coolant take the heat away to the radiator. The whole lot is pumped round fairly slowly by the coolant (water) pump.

    So there it is, an engine. Simple in principal but tricky in the details.

  • Getting that Practical Edge

    The world is changing, fast, and to keep up we all need to up-skill. In the vehicle fleet world the rate of change in technology is astonishing, technicians need to keep up, and that’s where we come in.

    Using our hands on experience and a unique way of teaching that is tailored to the way engineers and mechanics work we help people learn usable skills fast.