Chevrolet has been producing the Three hundred fifty small-block engine since 1968. Known for its simple design and durability, many 350s produced decades ago are still on the road today. Like any other engine, the Three hundred fifty does require periodic tune-ups or power will decline, performance will suffer and emissions produced by the engine will increase. More modern 350s use a box which splits into two halves. A number of clips secures the halves together. Remove the clips with a screwdriver and lift the upper half of the assembly off, followed by the air-cleaner element.
As the engine rotates, the rotor underneath the distributor cap spins. At the tip of the rotor is a metal piece, which strikes metal contacts within the distributor cap and sends current to the spark plugs via the spark plug wires. Ignition timing refers to the point in time when the spark is sent to the spark plugs. If the timing is not correct, the engine will feel sluggish and the fuel mileage will suffer. In extreme cases, the engine will back fire. Setting the timing requires a timing tight. Connect the timing light to the engine following the manufacturer's instructions, then mark the number "4" which appears on the lip of the harmonic balancer with chalk. Also note the metal timing tab just above the harmonic balancer on the passenger's side of the water pump. Loosen the single nut underneath the distributor with a wrench, then start the engine. Point the light at the harmonic balancer and observe the light flash. The timing pointer and the chalk mark should align. If they do not, the timing is incorrect. Rotate the distributor slightly until the marks are in alignment, then turn the engine off, disconnect the timing light and tighten the distributor's hold-down bolt.
Clean and Gap the Spark Plugs
Now that the timing is set, it is important to check the condition and the gap of the spark plugs. Because the Three hundred fifty has eight cylinder's, it has eight spark plugs. Remove the spark plugs and inspect the metal tip of each plug for ash-colored deposits. These deposits can suppress the plug's ability to produce a spark, which costs the engine power and reduces its fuel efficiency. Gently clean the tip of any fouled spark plug with a wire brush. "Gapping" the spark plugs refers to adjusting the distance between the two metal contact points at the tip of each plug. This gap is necessary for the plug to produce a sufficient spark. The Three hundred fifty Chevy requires a distance of .035 of an inch between these two points. Measure the distance between the two points with a feeler gauge. To adjust the distance, gently bend the metal tip on the plug that looks like a hook.
Clean the Air Filter
As its name suggests, the sole purpose of the air filter is to filter any large particles out of the air before it reaches the fuel delivery system, whether a carburetor or fuel injectors. Because the Three hundred fifty Chevy has been in use since 1968, the style of the engine's air filter differs. However, cleaning the air filter is the same no matter which style is used. Older 350's use a round air cleaner housing with a single wing-nut which holds the assembly's lid on. Remove the wing-nut, then lift off the lid followed by the air cleaner element. However, the parts and labor required for tune-ups can be expensive. Thankfully, there are a few tips for tuning-up a Three hundred fifty Chevy at no cost.
