The Stovebolt Site Forums The Shop Area Engine Shop Using a timing light

Since so many of these old engine/clutch-assemblies have been moved around, it should be noted that TDC/UC (valve timing mark) is in the same location on the flywheels for all engines. (please correct me, if this is incorrect - did some/all 261s have different valve timing marks compared to some same-year 235s)

However, the timing marks differed between 1937 and 1963 on 216/235/261 engines (for different BTDC or ATDC timing settings). The timing marks on your flywheel might not match your engine (to say nothing about original timing marks not being useful due to different octane modern gasoline)?

Those are a few of the reasons why adjusting/setting timing using the maximum-vacuum technique or the "ping" technique are usually better than using a timing light.