At the core of classic car engine mechanics is the principle of Fuel, Spark and Air……
Actually this runs right through to all modern diesel and petrol engines but its almost entirely relevant to our classic car and trucks engines. The principle is a simple one. An engine needs these three key elements to be able to fire. Get it roughly right it and it will run. More modern engines factor in things like ECU’s and sensors which can immobilise engines or prevent running. When it comes to our old cars whether its Retro Ford‘s or American classic muscle cars these three elements are crucial to the running of your vehicle. On a daily basis when we’re trouble shooting a non starting vehicle we look at these elements. 9 times out of 10 a non starting retro engine will be due to a lack of fuel or a lack of spark. Air might come into it on some engines particularly early fuel injected ones but more in terms of impacting running as opposed to starting. Lets take a look at an example to better explain.
One of our technicians was faced with sudden non starting of a Chevrolet 5.0 V8 engine. This 1980’s model ran a carburettor. On turning it over, with the air box off, it was clear that fuel was being sprayed into the carb. Next pulling a plug and earthing it showed no spark. Following that back he looked at power into the ignition coil. It was entering one side but not leaving the other headed for the distributor. Thus a diagnosis of failed coil was made. Replaced the coil and we had spark, add that to the fuel and air and it fires.
So whilst we have the three key elements in place it may run but it may not run right by ensuring the three things are running right you will in turn get a correctly running engine. Here are some (not all) considerations that might affect fuel, spark and air.
Fuel – fuel pump condition, carburettor settings, fuel filter condition, fuel lines,.
Spark – spark plug and spark plug leads condition, distributor condition, ignition coil condition. Immobiliser faults, battery, some sensors like ignition control modules.
Air – blocked air filters, split pipes, mass air flow sensors.
These things can impact on your fuel, spark and air. Getting the right will ultimately help to make your engine run better or right. Whether you are working on the vehicle yourself or whether you are working with a classic car repair garage or specialist these simple principles give you an understanding of why your engine is or isn’t running or running right.
