![]() These cylinders will use the same mark on the harmonic balancer: Cylinders 1 and 6 will use 30 degrees, 8 and 5 use 300 degrees, 4 and 7 use 210 degrees, and 3 and 2 use 120 degrees. We use 30-degrees ignition advance as a baseline because it minimizes the complexity of the math. ![]() It is still 30 degrees BTDC on each cylinder, but we need to think of it in crank-rotation degrees to tune the ignition timing. If we add the ignition advance, we see that a spark plug fires at 30-, 300-, 210-, and 120-degrees rotation of the crank. Draper Xenon Timing Light is suitable for checking ignition timing on automotive, agricultural and marine engines (12V DC). For that reason ignition timing on distributor-timed engines can be checked both statically with the engine turned off, and with it. Turn off the engine and reinstall the air cleaner. Tighten the distributor hold down bracket bolt. Align the mark on the harmonic balancer with the 12 degrees notch on the timing pointer. There will typically be a timing mark on the engine’s crankshaft pulley. Aim the timing light at the timing pointer on the front of the timing cover and rotate the distributor to adjust timing. With a 360-degree rotation, that means a piston is reaching TDC at zero-, 270-, 180-, and 90-degrees crank rotation as marked on the harmonic balancer. In engine speak, the ignition timing must be advanced as revs and load on the engine increase. Second, realize that the ignition fires 30 degrees BTDC every 90 degrees throughout the firing order. First, you must realize that the damper has 360 degrees marked as zero degrees, and that, in rotation, we count down from 360 degrees to zero on the balancer-not up. In order to do this, there is a certain amount of math to understand. We use the brightest timing light available-the French Grimes Winston Cup timing light. To tune the engine, you need to have the timing constant throughout the firing order. Check out Circle Track as they discuss the best ignition timing on an engine for maximum performance.
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